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    <Item taxon="book"/><Page><Page_no>1</Page_no><display_no>Cover</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[pea$:$0WULxaMo45yld0579a34FA==$:$nce S.B. NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>2</Page_no><display_no>Blank</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[]]></TextData></Page><Page><Page_no>3</Page_no><display_no>i</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[]]></TextData></Page><Page><Page_no>4</Page_no><display_no>ii</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Pearson Australia (a division of Pearson Australia Group Pty Ltd) 707 Collins Street, Melbourne, Victoria 3008 PO Box 23360, Melbourne, Victoria 8012 www.pearson.com.au Copyright © Pearson Australia 2013 (a division of Pearson Australia Group Pty Ltd) First published 2013 by Pearson Australia 2016 2015 2014 2013 10 9 8 7 6 5 4 3 2 1 Reproduction and communication for educational purposes The Australian Copyright Act 1968 (the Act) allows a maximum of one chapter or 10% of the pages of this work, whichever is the greater, to be reproduced and/or communicated by any educational institution for its educational purposes provided that that educational institution (or the body that administers it) has given a remuneration notice to Copyright Agency Limited (CAL) under the Act. For details of the CAL licence for educational institutions contact Copyright Agency Limited (www.copyright.com.au). Reproduction and communication for other purposes Except as permitted under the Act (for example any fair dealing for the purposes of study, research, criticism or review), no part of this book may be reproduced, stored in a retrieval system, communicated or transmitted in any form or by any means without prior written permission. All enquiries should be made to the publisher at the address above. This book is not to be treated as a blackline master; that is, any photocopying beyond fair dealing requires prior written permission. Publishers: Misal Belvedere, Ross Laman and Malcolm Parsons Project Managers: Jane Sunderland and Michelle Hessels Editors: Marcia Bascombe, Elaine Cochrane and Kay Waters Series Cover Designer: Glen McClay Text Designer: Kim Ferguson Copyright & Pict$:$NqmI7rwMdePIKzEWIdhfOAaJgcI72ekQeeFFhEXOzF07yJeOqAsU6ttTHbUpHodwJubmPdd+LLBL
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pgbTOKo=$:$ may have ceased to exist since publication, or may inadvertently link to sites with content that could be considered offensive or inappropriate. While the authors and publisher regret any inconvenience this may cause readers, no responsibility for any such changes or unforeseeable errors can be accepted by either the authors or the publisher. Some of the images used in Pearson Science New South Wales Student Book 7 might have associations with deceased Indigenous Australians. Please be aware that these images might cause sadness or distress in Aboriginal or Torres Strait Islander communities. Practical activities: All practical activities, including the illustrations, are provided as a guide only and the accuracy of such information cannot be guaranteed. Teachers must assess the appropriateness of an activity and take into account the experience of their students and facilities available. Additionally, all practical activities should be trialled before they are attempted with students and a risk assessment must be completed. All care should be taken and appropriate protective clothing and equipment should be worn when carrying out any practical activity. Although all practical activities have been written with safety in mind, Pearson Australia and the authors do not accept any responsibility for the information contained in or relating to the practical activities, and are not liable for any loss and/or injury arising from or sustained as a result of conducting any of the practical activities described in this book. ]]></TextData></Page><Page><Page_no>5</Page_no><display_no>iii</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Acknowledgements Alamy: p. 63; Roger Allen, $:$UNtzXB+wjC3kSseo6Li5H3NNg0t0kzS4FWVdLUVAwupg6OlQ9fBcGSIpNilpo/cWfZmp8ZXJLu2p
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LG3RLACahw==$:$l, 253bc, 260tr, 261tl, 261bl, 263 (snake), 264b, 267b, 271t, 280b, 291bl, 296, 300, 344r, 364b. Droughtmaster Australia: p. 214bl. Fairfax Photo Sales: Sebastian Costanzo, p. 174; Robert Peet, p. 93. Fotolia: pp. 56l, 87br, 103tr, 213r, 267t, 271cr, 271bl, 271br. Getty Images: pp. 201l, 232, 340; Theo Allofs, pp. 210bc, 226br; James L Amos, p. 4; Frank Bean, p. 22; Bloomberg, p. 169; Robin Bush, p. 216; Peter Cade, p. 262r; John Cancalosi, p. 48r; Laurence Dutton, p. 43; Jason Edwards, pp. 184tr, 199b; Cathy Finch, p. 182t; Michael Patricia Fogden, p. 127t; Jeff Foott, p. 148; Stephen Frink, p. 72t; Borut Furlan, p. 241bl; Fuse, p. 20l; Jacky Ghossein, p. 212r; Jorg Greuel, p. 38tr; ML Harris, p. 263 (fern); Peter Harrison, p. 122l; Nicole Hill, p. 35; Karen Kasmauski, p. 150l; Mike Kemp, p. 38bc; Andrew Lambert, p. 158; Gary Lewis, pp. 210bl, 226tr; Trevor Lush, p. 289t; Francois Xavier Marit, p. 291br; Ted Mead, pp. 200tr, 215br; Lucia Meler, p. 142r; Mycenaean, p. 74; Flip Nicklin, p. 293; Alfred Pasieka, p. 290l; Photo Researchers, p. 19; Picture Researchers, p. 27; Mike Powles, p. 185r; Purestock, p. 291tcl; Jim Reed, p. 91r; Ed Reschke, pp. 186br, 225bl; Tim Ridley, p. 71b; Claudio Santana, p. 312; Joel Sartore, p. 89; Sijanto, p. 180; Robin Smith, pp. 200cr, 201t, 226tl; Doug Steakley, p. 3t; Clive Streeter, p. 71; Brendon Thorne, p. 191; Tier Und Naturfotografie J & C Sohns, p. 184tl; John White, p. 192tl; Charles D. Winters, pp. 12b, 140l, 140tr, 144b, 306; David Woodfall, p. 154; James Worrell, pp. 62b, 83br; Linda Wright, cover, p. i; Norbert Wu, p. 210br. iStockphoto: pp. 228t, 237b, 238c, 239tr, 241tr, 241br, 250br, 253tr, 271cl, 274bl, 291bcl. Linstead, Greg: pp. 117, 125r, 353. Kinsey, Ron: p. 253tl. Lochman Transparencies: pp. 142l, 263 (blue gum). NASA: pp. 3 (astronomy), 88b, 322, 329, 334b, 346tr, 362; Boeing/Bob Ferguson, p. 52b; Edwin E. Buzz Aldrin, p. 337; Anthony Ayiomamitis, p. 21b; Earth Observatory, pp. 85, 112b; MODIS Rapid Response Team, p. 200bl. National Archives of Australia: (11145789), p. 204bl. Natural History Museum Picture Library: p. 245t. New Scientist: © Reed Business Information Ltd, p. 101. Newspix: pp. 5bl, 11; Aaron Francis, p. 183t; Jeff Herbert, p. 5t; Dan Himbrechts, p. 201b; Sarah Reed, p. 200br. Orange City Council: Andrew Griffith, p. 125bl. Pearson Australia: Alice McBroom, pp. 10b, 21t, 34, 48l. Photoshot: pp. 205t, 205bl; D & M Trounson, p. 265bl; Martin Willis, p. 265br; Daniel Zupanc, p. 265bc. Random House, Inc: Dr Seuss, Bartholomew and the Oobleck, 1949. With permission from Random House, Inc., p. 51l. Roberts, Lauren Jolly: p. 126l. Science Photo Library: pp. 13 (main), 83tl, 83tr, 64bl, 159t (all), 178br, 281b, 332t; Chris Martin Bahr, p. 65; Alex Bartel, p. 305; Dr Tony Brain, p. 257t; Alex Cherney, p. 325t; Martyn F. Chillmaid, pp. 141t, 178bl; Tony Craddock, p. 103br; Crown Copyright/Health & Safety Laboratory, p. 45r; Andy Crump, p. 159b; Dr Fred Espenak, p. 348l; Eye of Science, pp. 257b, 291tr; Mark Garlick, pp. 327t, 349; Steve Gschmeissner, pp. 240tl, 257c; Roger Harris, p. 56r; Gary Hincks, p. 346tl; Mikkel Juul Jensen, p. 345r; David Hay Jones, p. 10t; Russell Kightley, p. 53br; Andrew Lambert, pp. 73, 140br, 141b, 178tl; Lawrence Lawry, pp. 45bl, 58r; Kenneth Libbrecht, p. 64br; Microfield Scientific LTD, p. 253tr; Cordelia Molloy, p. 345l; NASA, pp. 298b, 299l, 323b, 346bl; NASA/JPL-Caltech/University of Arizona, pp. 31, 45t; David Nanuk, pp. 102r, 323t, 328, 354l; Walter Pacholka, p. 326r; Pekka Parvianen, p. 348r; Marie Perennou, p. 64t; Philippe Plailly, p. 57; Planetobserver, p. 354r; Detlev Van Ravenswaay, pp. 53, 325b; Daniel Sambraus, p. 58l; John Sanford, pp. 324l, 339 (all); Power and Syred, p. 289b; Sinclair Stammers, pp. 12t, 254tl; Volker Steger, pp. 107t, 107b; Babak Tafreshi, pp. 324r, 326l; David Taylor, p. 13(inset); TEK image, p. 151; Sheila Terry, pp. 223, 260b; Geoff Tompkinson, p. 164. Shutterstock: pp. 1, 2, 3 (chemistry), 3 (ecology), 3 (geology), 5cl, 5c, 5cr, 5br, 6, 16, 32, 38bl, 38br, 44l, 54r, 72b, 84, 86r,87tr, 88t, 88tr, 90t, 92, 94, 102l, 112t, 113, 116, 117l, 119 all, 122r, 123br, 126r, 132, 136tl, 136cl, 136bl, 137cr, 137bl, 138, 139, 144t, 152t, 152b, 153, 171, 165, 167t (all), 167b, 181b, 184br, 186tr, 188, 193 (all), 192tr, 192br, 193 (all), 196, 199c, 203, 204t, 210t, 214tl, 215l, 215tr, 225tl, 225cr, 229b, 230tr, 230cr, 230br, 231t, 234, 236, 237t, 240bl, 241tl, 242tr, 243tr, 243cr, 243br, 244c, 244b, 249b (inset), 250t, 250bl, 253bl, 259, 262l, 263 (red kangaroo), 263 (eastern grey kangaroo), 263 (spider), 273tl, 273br, 274cl, 276, 277, 278 (all), 282, 288, 291tl, 298t, 302, 308 (all), 311, 321, 335r, 344l, 355b, 355t. Spenceley, Maggie: p. 127b. Starr, Forest and Kim: p. 263 (grey iron bark). Thinkstock: pp. 3 (biology), 3 (psychology), 3 (physics), 20r, 38tl, 38t, 44r, 47, 54l, 104, 168r, 181t, 185l, 190, 194 (all), 198b, 208, 211b, 213l, 238t, 239bc, 240br, 249b. Wildlight: Jaime Plaza, pp. 252l, 252br, 263 (Wollemi); Penny Tweedie, p. 264t. We would like to thank the following for permission to reproduce copyright material. The following abbreviations are used in this list: t = top, b = bottom, l = left, r = right, c = centre. Every effort has been made to trace and acknowledge copyright. However, if any infringement has occurred, the publishers tender their apologies and invite the copyright holders to contact them. ]]></TextData></Page><Page><Page_no>6</Page_no><display_no>iv</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Greg Rickard Teacher, Former Head of Department Coordinating Author Misal Belvedere Publisher, Pearson Australia Alicia Brown Publisher, Pearson Australia Dr Warrick Clarke Education Research Solutions Author, New South Wales Jacinta Devlin Teacher Author, Victoria Peter Gribben Teacher, Head of Department Reviewer, New South Wales Merrilyn Lean Teacher, Head of Department Reviewer, New South Wales Greg Linstead Teacher, Former Head of Department Author, Western Australia Ca$:$pnFL1vbCUiYZiL66aDEEyd3adUalz8TjYnlYzekoo+2BOeRcuO+cZ3Z6690QX+Jmw7skErox6IaO
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hURhzn/MkuRouMkS$:$ions 303 7.4 Magnetic and electric fields 305 Learning across the curriculum Lightning 311 7.4 Unit review 313 7.4 Practical investigations 315 Chapter review 318 Thinking scientifically 320 Glossary 321 8 Earth in space 8.1 The night sky 323 8.1 Unit review 328 8.1 Practical investigations 330 8.2 Discovering the solar system 332 Learning across the curriculum Interpreting constellations 338 8.2 Unit review 340 8.2 Practical investigations 342 8.3 Gravity, tides and orbits 344 8.3 Unit review 350 8.3 Practical investigations 351 8.4 Earth 353 8.4 Unit review 357 8.4 Practical investigations 359 Chapter review 361 Thinking scientifically 363 Glossary 364 Index 365 vii ]]></TextData></Page><Page><Page_no>10</Page_no><display_no>viii</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[NEW SOUTH WALES viii PEARSON science NEW SOUTH WALES Student Book Written from the ground up for the Australian Curriculum and developed specifically for the NSW Science Syllabus for the Austral$:$59rdkhpMKbfwrVMje/80RS+T6t2Q6McgmOWGOuEn4w2XLNOkL1oguB8fgZnVK2IEi1gsI3M0spKU
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pn4tvDTuG53og8xBZ+3WXQ==$:$s to reinforce learning outcomes. • Supports and extends the student book • Caters for a range of learning styles. Teacher Companion The teacher companion makes lesson preparation easy by combining full-colour textbook pages with teaching strategies, ideas for class activities and fully worked solutions. • Ties the entire Pearson Science New South Wales package together • Includes all answers to the student and activity book. EAL/D Activity Book The EAL/D activity book incorporates tailored language and vocabulary support for English as an Additional Language or Dialect (EAL/D) learners. With activities matching page-for- page, the EAL/D activity book can be used alongside the standard activity book. pearson science A.B. NEW SOUTH WALES pearson science A.B. NEW SOUTH WALES pearson science A.B. NEW SOUTH WALES pearson science A.B. NEW SOUTH WALES pearson science S.B. NEW SOUTH WALES pearson science T.C. NEW SOUTH WALES pearson science T.C. NEW SOUTH WALES pearson science S.B. NEW SOUTH WALES pearsonpearson science S.B. NEW SOUTH WALES pearson science T.C. NEW SOUTH WALES pearson science S.B. NEW SOUTH WALES pearson science T.C. NEW SOUTH WALES PEARSON science ]]></TextData></Page><Page><Page_no>11</Page_no><display_no>ix</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Browse and buy at pearson.com.au. Access your content at pearsonplaces.com.au. PearsonDigital ix Pearson eBook 3.0 Any device, every school. Pearson eBook 3.0 lets you use your student book online or offline on any device: PC or Mac, Android tablet or iPad, or interactive whiteboard. Pearson eBook 3.0 retains the integrity of the printed page while off$:$a22yn3dVZMAuQAx+J/A3p19qkj10dM/gzX2PCIlOlkk0QMwE3J16lzg9cLbRNbK+SkDl8BQQaEEH
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gLEliCMw4PrG0fP7q+Jj6YdTN4jis5R+2SaIp8uJFBmQyz+1S5hecW6mzQxi53Uk$:$n you purchase Pearson Science New South Wales. To access, visit www.pearsonplaces.com.au and log in. Click on ‘Toolkit’, then select ‘ProductLink’ and browse to your title. Professional Learning, Training and Development Did you know that Pearson also offer teachers a diverse range of professional learning programs? We are dedicated to supporting your implementation of Pearson Science New South Wales, but it doesn’t stop there. We offer specific training for the NSW Syllabus for the Australian Curriculum and beyond, in the form of workshops, conferences and seminars. Find out more about Pearson Professional Learning at www.pearson.com.au/pl Customised Content We believe in learning for all kinds of people, delivered in a personal style. Pearson Custom is an exciting initiative that allows you to customise the content you teach with. Schools can be involved in choosing resources specifically tailored to their school or year level. Speak to your Pearson Sales Consultant to find out more. We believe in learning. All kinds of learning for all kinds of people, delivered in a personal style. Because wherever learning flourishes, so do people. ]]></TextData></Page><Page><Page_no>12</Page_no><display_no>x</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[PEARSON science NEW SOUTH WALES 7 Student Book PEARSON science NEW SOUTH WALES 7 has been designed for Stage 4 of the NSW Science Syllabus for the Australian Curriculum. It includes content and activities that cover all learning outcomes within the interrelated strands of Knowledge and Understanding, and Working Scientifically. The content is presented through a range of contexts to engage students and assist them to make connections between science and their lives. Additional syllabus content is clearly identified and carefully placed in the flow of core content. Learning Across the Curriculum content is addressed through- out the series and indicated using icons. PEARSON science NEW SOUTH WALES 7 is designed for an inquiry approach to science learning. Its engaging design, unambiguous features and clear easy-to-understand language make this a valuable resource for students of all interests and abilities. Chapter opening page The chapter opener engages students through questions that get them thinking about the content and concepts to come. The key ideas reflect the syllabus content relevant to the chapter. Look who is using science Careers pages spread throughout the book look at careers that involve and use science. Unit opening Each chapter is divided into self-contained units. The unit opener includes an introduction that places the material to come in a meaningful context. Photos and illustrations Stunning and relevant photos and illustrations are clearly referenced from within the text to assist stu dents to understand the idea being developed. science4fun Inquiry-based activities using everyday materials assist students to understand key concepts under development. These can be used as a focus or context for the unit. Icons indicate whether an activity is suitable to be done at home or requires teacher supervision. Skill builder Key skills are outlined in clear steps to support science learning. Worked example Worked examples of problems and techniques assist students to master and practise key skills. Additional content Additional syllabus content is clearly identified using shading and icons. 2 Properties of substances • describematterintermsof particles • outlinehowparticlemovementis relatedtoenergy • usetheparticlemodeltopredict whathappenswhendifferent statesofmatterareheatedor cooled • explainhowthephysical propertiesofmatterchange duringchangesofstate • explaindensityintermsofthe particlemodel • identifythebenefitsand limitationsofusingmodelsto explainsolids,liquidsandgases CCT ADDITIONAL • researchhowAboriginaland TorresStraitIslanderpeoplesuse thephysicalpropertiesofnatural materialsineverydaylife AHC • investigatehowthechemical propertiesofasubstanceaffect itsuse • explainhowgaspressureis relatedtothefrequencyof particlecollisions • outlinehistoricaldevelopments thathaveadvancedour understandingoftheparticle model. Aftercompletingthischapterstudentsshouldbeableto: Have you ever wondered... • whysolids,liquidsand gasesappearsodifferent? • whyclothesdryeven whenit’snothot? • whyyoubreatheoutfog onacoldmorning? • whyicebergsfloat? 42 PEARSON science NEW SOUTH WALES Some materials like lead, gold, granite and steel are very heavy for their size. Other materials like foam rubber, cork, balsa wood and feathers are so light that huge piles don’t weigh much at all. Density measures how much matter is packed into a space. Density determines how heavy a handful of a substance will be and whether it floats or sinks in water. Density2.4 Density:aphysicalproperty The physical properties of a substance describe things such as: • its appearance • the temperatures at which it melts, freezes and boils • its hardness (how easy it is to scratch the material). Density is one of the physical properties of a substance. Density depends on how heavy a substance is, but it is not the same as its weight or mass. For example, 1 kilogram of lead always weighs exactly the same as 1 kilogram of polystyrene, which weighs as much as 1 kilogram of feathers. Density instead measures how much matter is packed into a specific space (Figure 2.4.1). Figure 2.4.1 Stones are much more dense than feathers. This makes a small pile of stones weigh a lot more than a big pile of feathers. science fun Saltylavalamp Can you make your own lava lamp? Collectthis… • cooking oil • salt shaker • food dye • water • tall glass or 250mL beaker Dothis… 1 Pour water into the glass or beaker until it is one-third full. 2 Add a few drops of food dye. 3 Pour in an equal quantity of cooking oil and observe which layer is on top. 4 Sprinkle salt into the glass and carefully observe what happens to the grains of salt. Recordthis… Describe what happened. Explain why you think this happened. Properties of substances 71 SCIENCE TAKES YOU PLACES Look who is using science TAXONOMIST My name is Dr Will White and I am a fish taxonomist with the CSIRO Marine and Atmospheric Research laboratories. I work on applied taxonomy and biogeography of Indo- Pacific fishes, mostly sharks and rays. A large proportion of my work has involved field trips to Indonesia to look at the fisheries over there and I have discovered a large number of new species of sharks and rays during this work. I have been involved in the description of almost 50 new species of sharks and rays. I always had an interest in sharks and rays and have always enjoyed diving and underwater photography. Science has been a great way not only to learn new things but also to lead a varied work life with a large amount of travel. SEWAGE QUALITY ENGINEER My name is Brett Maurer and I am a sewage quality engineer working for City West Water. Trade waste (waste released into the sewers from industry) can potentially contaminate and damage pipes and sewage treatment plants. It can also put our sewer workers at risk, particularly if it is releasing dangerous gases. I take samples of sewage and test them to determine what contaminants they contain and whether they meet the regulations for discharging into the sewer. I also collect samples from the space in the pipe above the flowing sewage to determine what gases are there. The information obtained also helps our business identify ways of treating and recycling industrial water and using biosolids—the nutrient-rich sludge that is generated from the treatment plant process. Water is essential for living and my work helps to ensure that supply meets the increasing demand of our increasing population. ENVIRONMENTAL SCIENTIST My name is Adeline Morrissey and I am an environmental scientist working in the mining industry. In my job I help mining companies to look after the environment. One of my jobs is to do water sampling to check whether the mine site is contaminating the groundwater. I also study how well a company has restored the areas where they have mined. This involves studying the soil and plants. I assist with surveys of animals before companies mine areas to see what animals are present, such as rare species. I am regularly back in the city for report writing and data analysis after I do the field work. The sciences I studied at school and university that I use in my everyday job include chemistry, biology, soil science, plant science and animal sciences. 179 Other equipment used for heating A kitchen stove isn’t very useful unless you have frying pans, saucepans, tongs and stirring spoons to help you cook the food safely. A Bunsen burner also needs additional equipment to help you heat objects and to keep you safe. Some of this equipment is shown in Figure 1.2.8. hottest part of flame cone of unburnt gas The blue flame is: • hot • clean • difficult to see. The yellow flame is called the safety flame. It is: • relatively cool • dirty • highly visible. The yellow flame is easy to see and relatively cool. The blue flame is much hotter and almost invisible. This makes it much more dangerous. Figure 1.2.7 Tongs and pegs: allow you to pick up hot objects Clay triangle: used to support a crucible Gauze mat: used to spread the heat Tripod: used to hold beakers above the flame Retort stand, bosshead and clamps: used to hold other equipment Crucible and lid: used to burn small samples of solid Evaporating dish: used to evaporate off the solvent from a solution, leaving crystals behind Bench mat: used to protect the bench The hotplate and Bunsen burner need additional equipment to make them useful. 4.61.2 Figure 1.2.8 Heating a test-tube Test-tubes can spit out their contents if you heat them incorrectly. 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WHaXgtWLVEsrosIQ5xJP6i5h11Q098fyc6W2jEeHxW/59u9oIKnewS8hyslJMXTy$:$nce 1 mL is exactly the same as 1 cm3 . 1 mL = 1 cm3 Likewise, masses are sometimes measured in kilogram or tonne. If so, then they need to be converted into gram. Table 2.4.4 shows how. Table2.4.4Convertingmassandvolume Measurement From Convert by To Mass tonne (t) x 1000000 gram (g) kilogram (kg) x 1000 gram (g) Volume litre (L) x 1000 millilitre (mL) millilitre (mL) x 1 cubic centimetres (cm3 ) Problem 1 Convert 3 kg into g. 2 Convert 2.5 t into g. 3 Convert 375 mL into cm3 . 4 Convert 1.25 L into cm3 . Solution 1 3 × 1000 = 3000 g 2 2.5 × 1000000 = 2500000 g 3 375 × 1 = 375 cm3 4 1.25 × 1000 = 1250 cm3 Practice N Calculate what these measurements are in the units indicated. a 2 L into cm3 b 4 kg into g c 1.1 t into g Unit conversions WORKEDEXAMPLE The volume of a liquid can be measured accurately using a measuring cylinder. The volume of liquids is usually measured in litres (L). For example, large bottles of soft drink come in 1.25 L and 2 L sizes. Smaller volumes are usually measured in millilitres (mL). For example, cans of soft drink normally hold a volume of 375 mL. As Figure 2.4.7 shows, a measuring cylinder can also be used to find the volume of a solid. When you place a solid in water, it displaces (takes the place of) a volume of water equivalent to its own volume. That’s why the level of water in the bath goes up when you get in. Eureka! Archimedes (about 287 to 212 BCE) needed to calculate the density of the wreath or crown of his king to determine whether it was pure gold. But how could he measure its volume without destroying it? He realised how when he got into his bath and saw the water level rise. So excited, he supposedly ran naked down the street screaming ‘eureka, eureka’! 2.6 74 PEARSON science NEW SOUTH WALES How to use this book 100 90 80 70 60 20 30 40 50 10 100 90 80 70 60 20 30 40 50 10 60 mL 90 mL 30 mL The volume of a solid can be determined by dropping it into a measuring cylinder. If the level goes up by 30 mL then the solid’s volume must be 30 mL. Figure 2.4.7 Unit conversions Density is measured in g/cm3 . This means that mass must be in gram and volume in cm3 . But a measuring cylinder gives its volumes in mL. This means that volume needs to be converted from mL to cm3 . This is easy since 1 mL is exactly the same as 1 cm3 . 1 mL = 1 cm3 Likewise, masses are sometimes measured in kilogram or tonne. If so, then they need to be converted into gram. Table 2.4.4 shows how. Table2.4.4Convertingmassandvolume Measurement From Convert by To Mass tonne (t) x 1000000 gram (g) kilogram (kg) x 1000 gram (g) Volume litre (L) x 1000 millilitre (mL) millilitre (mL) x 1 cubic centimetres (cm3 ) Problem 1 Convert 3 kg into g. 2 Convert 2.5 t into g. 3 Convert 375 mL into cm3 . 4 Convert 1.25 L into cm3 . Solution 1 3 × 1000 = 3000 g 2 2.5 × 1000000 = 2500000 g 3 375 × 1 = 375 cm3 4 1.25 × 1000 = 1250 cm3 Practice N Calculate what these measurements are in the units indicated. a 2 L into cm3 b 4 kg into g c 1.1 t into g Unit conversions WORKEDEXAMPLE The volume of a liquid can be measured accurately using a measuring cylinder. The volume of liquids is usually measured in litres (L). For example, large bottles of soft drink come in 1.25 L and 2 L sizes. Smaller volumes are usually measured in millilitres (mL). For example, cans of soft drink normally hold a volume of 375 mL. As Figure 2.4.7 shows, a measuring cylinder can also be used to find the volume of a solid. When you place a solid in water, it displaces (takes the place of) a volume of water equivalent to its own volume. That’s why the level of water in the bath goes up when you get in. Eureka! Archimedes (about 287 to 212 BCE) needed to calculate the density of the wreath or crown of his king to determine whether it was pure gold. But how could he measure its volume without destroying it? He realised how when he got into his bath and saw the water level rise. So excited, he supposedly ran naked down the street screaming ‘eureka, eureka’! 2.6 74 PEARSON science NEW SOUTH WALES Animals, trees, soil, rocks, water, air and sunlight are natural resources. Figure 3.1.1 All life depends on these resources. Protecting them gives all living things (including us) a better chance of survival. Maderesources Not all resources are natural. Some are made by us humans. Made resources start as natural resources. Some important made resources are: • foods, such as pasta and the bread in Figure 3.1.2, made from plant seeds Bread is a made resource. It’s produced from natural resources such as plant seeds like wheat, soy and rye. Figure 3.1.2 ADDITIONAL Technologyandmade resources The variety of made resources increases as new technology is discovered. This means that new materials are continually being developed. For example, plastics were invented around 1900. Since that time, the use of plastics has become so widespread that they now replace wood, metal, cardboard and paper in many applications such as toys, computer cases, furniture, shopping bags, packaging trays, banknotes, and car and aircraft body parts. Carbon fibre was developed more recently as a strong but lighter replacement for metal. It is now used in F1 racing cars, tennis racquets, golf clubs, hockey sticks, bike frames and wheels, and the masts of yachts. Our ever-increasing understanding of genetics has led us to breed better plants and animals. In this way the Other equipment used for heating A kitchen stove isn’t very useful unless you have frying pans, saucepans, tongs and stirring spoons to help you cook the food safely. A Bunsen burner also needs additional equipment to help you heat objects and to keep you safe. Some of this equipment is shown in Figure 1.2.8. hottest part of flame cone of unburnt gas The blue flame is: • hot • clean • difficult to see. The yellow flame is called the safety flame. It is: • relatively cool • dirty • highly visible. The yellow flame is easy to see and relatively cool. The blue flame is much hotter and almost invisible. This makes it much more dangerous. Figure 1.2.7 Tongs and pegs: allow you to pick up hot objects Clay triangle: used to support a crucible Gauze mat: used to spread the heat Tripod: used to hold beakers above the flame Retort stand, bosshead and clamps: used to hold other equipment Crucible and lid: used to burn small samples of solid Evaporating dish: used to evaporate off the solvent from a solution, leaving crystals behind Bench mat: used to protect the bench The hotplate and Bunsen burner need additional equipment to make them useful. 4.61.2 Figure 1.2.8 Heating a test-tube Test-tubes can spit out their contents if you heat them incorrectly. They can also break. 1 Use a peg or test-tube holder to hold the test-tube near its open end. 2 Point the opening of the test-tube away from everyone, including yourself. 3 Heat the bottom gently, moving it back and forth through the flame as shown in Figure 1.2.9. Never leave a test-tube in the one spot in a flame for too long. Figure 1.2.9 Working scientifically 13 Some materials like lead, gold, granite and steel are very heavy for their size. Other materials like foam rubber, cork, balsa wood and feathers are so light that huge piles don’t weigh much at all. Density measures how much matter is packed into a space. Density determines how heavy a handful of a substance will be and whether it floats or sinks in water. Density2.4 Density:aphysicalproperty The physical properties of a substance describe things such as: • its appearance • the temperatures at which it melts, freezes and boils • its hardness (how easy it is to scratch the material). Density is one of the physical properties of a substance. Density depends on how heavy a substance is, but it is not the same as its weight or mass. For example, 1 kilogram of lead always weighs exactly the same as 1 kilogram of polystyrene, which weighs as much as 1 kilogram of feathers. Density instead measures how much matter is packed into a specific space (Figure 2.4.1). Figure 2.4.1 Stones are much more dense than feathers. This makes a small pile of stones weigh a lot more than a big pile of feathers. science fun Saltylavalamp Can you make your own lava lamp? Collectthis… • cooking oil • salt shaker • food dye • water • tall glass or 250mL beaker Dothis… 1 Pour water into the glass or beaker until it is one-third full. 2 Add a few drops of food dye. 3 Pour in an equal quantity of cooking oil and observe which layer is on top. 4 Sprinkle salt into the glass and carefully observe what happens to the grains of salt. Recordthis… Describe what happened. Explain why you think this happened. Properties of substances 71 x PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>13</Page_no><display_no>xi</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Don’t forget the other PEARSON science NEW SOUTH WALES 7 package components that will help engage and excite students in science: • Activity Book • EAL/D Activity Book • eBook 3.0 • Teacher Companion • Pearson Assess New South Wales SciFile SciFiles include quirky information to engage students. Unit review Each unit finishes with a set of questions and activities organised under the headings of Bloom’s Taxonomy of Cognitive Processes. To further students’ understanding of the intent of a question and level of explanation expected, bolded verbs are used throughout. A list of all verbs and their meanings can be found on page xii. The final heading is ‘Inquiring’. These questions challenge students to use their inquiry skills to research additional syllabus content and to go beyond the unit content. Practical investigations Practical investigations are placed at the end of each unit. Practical investigation icons appear throughout the units to indicate suggested times for practical work. A Student-design icon indicates that an activity includes student input and design. Safety boxes highlight significant hazards. A safety glasses icon reminds students when appropriate to wear safety glasses. Learning Across the Curriculum Learning Across the Curriculum content is addressed throughout the Student Book using icons and in Learning Across the Curriculum spreads. A full list of Learning Across the Curriculum icons can be found on page xiii. Chapter review Each chapter finishes with a set of questions and activities organised under the headings of Bloom’s Taxonomy of Cognitive Processes. Thinking scientifically Following the Chapter review are Thinking scientifically style questions relevant to that chapter. These test students’ science and interpretive skills. Glossary Every chapter concludes with an illustrated glossary that engages students and provides a ready reference for the key terms of the chapter. Activity Book icon This icon indicates a related Activity Book worksheet that enhances or extends this area. Biological control One method of controlling unwanted pests is to introduce a predator of the pest or a type of organism that will compete with the pest for food or shelter. Using one type of organism to control the numbers of another type of organism is called biological control. This includes introducing a disease-causing organism that will kill the pest but not other species. The CurrICuLum LeArNINg ACrOSS sustainability Cactoblastis moth caterpillars Figure 5.3.17 The following are three examples of biological controls that have been tried in Australia. The Cactoblastis moth (Figure 5.3.17 and 5.3.18) was introduced into Australia in 1925 in an attempt to control the spread of the prickly pear cactus (Figure 5.3.19). The moths feed only on the cactus, and so they died out when they had eaten all the food. This was a big success and the problem of the cactus was solved within a few years. The cactus has not died out completely, but it is under control. The prickly pear cactus was brought to Australia by Captain Phillip on the First Fleet because it was a food source for a beetle that provided the red dye used for soldiers’ uniforms. Later it was grown as cattle feed and as a pot plant in gardens. The cactus spread very rapidly and at one stage covered an area the size of the state of Victoria. Figure 5.3.19 The Cactoblastis moth. The caterpillars (larvae) of this moth eat the prickly pear cactus. Figure 5.3.18 Habitats and interactions 205 88 PEARSON science NEW SOUTH WALES Animals are a renewable resource because they reproduce. Figure 3.1.6 Airasaresource Air is a mixture of gases and suspended particles such as dust, smoke and water droplets. The main gases in air and their importance to life on Earth can be seen in Table 3.1.1. Table3.1.1Gasesintheair Gas Percentage inair Importancetolife Nitrogen 78% Provides nutrients for plants to make proteins and other chemicals, which humans and other animals can use as food. Oxygen 21% Essential for most living things, to release energy from food for their bodies to use. Carbon dioxide 0.03% Essential for plants to make their own food by photosynthesis. Other gases such as ozone, water vapour and argon 0.97% Many uses depending on the gas. • Ozoneshieldshumans from ultraviolet rays (reducing our risk of skin cancers). • Watervapourispart of the water cycle that carries water around the planet. • Argonisusedinlight globes. Air:arenewableresource About 21% of the air is oxygen gas. Oxygen is constantly being used by animals and plants but is also constantly being replaced by plants. Green plants, like the one in Figure 3.1.7, use the energy from sunlight, carbon dioxide and water to make their own food. The process is called photosynthesis. As well as producing the plant’s food, photosynthesis also produces oxygen. This production allows the oxygen in the atmosphere to stay at about the same level. Scientists describe the movement of materials from one place to another and back again as a ‘cycle’. Oxygen cycles through the Earth’s atmosphere, soils, rocks, water and organisms.. Green plants use carbon dioxide, water and energy from sunlight to make their food (sugar) by the process of photosynthesis. Figure 3.1.7 Earth’s fragile atmosphere The atmosphere is the very thin layer of air around the Earth’s surface. The first astronauts who ventured into space were amazed at how thin and fragile the atmosphere looked from space. Many said it made them think very deeply about the damage humans are doing to the atmosphere. Chapter review5 Remembering 1 State why a producer organism is normally part of every food chain. 2 Recall the original source of energy for food chains. 3 List these in order from largest to smallest: habitat, biosphere, ecosystem. 4 List these groups of organisms from the ones that are most threatened to the ones that are least threatened: rare, vulnerable, endangered. 5 Recall the three outcomes of sustainably managed forests. Understanding 6 Explain why the habitat of an organism is sometimes referred to as its address. 7 Modify these scrambled sentences and rewrite with the words in the correct order. a ecosystem are All things an living in interdependent. b may feeds A is off organism parasite that kill its an host and it. c and sensitive Plants to environment animals changes are their in. 8 Figure 5.5.1 shows a food web where an eagle is the consumer at the top of the food chains. a Predict what would happen to the number of eagles in the area if foxes were introduced. (Note: foxes would eat koalas, birds and kangaroos.) b Modify the food web to include the foxes. eagle snake small bird insects kangarookoala trees decomposers grass Figure 5.5.1 9 Explain why it is necessary to produce new breeds of animals and varieties of plants for Australian conditions. Analysing 10 Compare the role of prey and predator in a habitat. 11 Classify the organisms in the following list as either producers or consumers: cat, magpie, rose, eucalypt, sparrow, worm, ant, grass, daisy. 12 Classify the following as biotic or abiotic environmental factors in a wetland ecosystem: water birds, water temperature, crocodile, rate of water flow, amount of salt in the water, water plants, frogs, fish. Present your answer in a table. Evaluating CCT 13 Lantana is a large flowering shrub that is native to Central and South America. It was introduced to Australia in 1841 as an ornamental garden plant that could be cut into a hedge. In the wild it grows rapidly along creek banks. It forms very dense bushes that prevent light from reaching the ground. Lantana grows in areas that are difficult to access and is not easy to remove. It has a prickly stem and the leaves are poisonous to livestock if eaten. Its seeds are contained in a cluster of fleshy black berries that birds love to eat. Use the information about Lantana to answer these questions: a Propose ways in which Lantana could affect the growth of native plants. b Propose ways in which Lantana could affect the number and species of native animals living in an area. c Propose actions that could be taken to prevent the spread of this plant. 14 Figure 5.5.2 shows the changes in the numbers of different animals found in an area for a period of 40 years. You are asked to interpret the information in this graph. a Identify the general trend in the population of the native animals (red-necked wallaby and eastern grey kangaroo). b Identify the general trend in the population of the rabbit—an introduced species. 222 PEARSON science NEW SOUTH WALES Earth resources 135 Thinking scientifically Q1 Arenewablenaturalresourceisonethat is replaced by natural processes that occur in a timescale less than an average human lifetime. Some students were asked to classify some of Earth’s resources into renewable resources and non-renewable resources. Their answer is shown in the following table. Renewable resources Non-renewable resources 1 rocks 7 wind 2 water 8 air 3 sunlight 9 coal 4 soil 10 petroleum 5 waves 11 natural gas 6 hydroelectric 12 nuclear Which resources (using the number) did the students classify incorrectly? A 1, 4, 7, 8 B 2, 3, 9, 10 C 5, 6, 11, 12 D 9, 10, 11, 12 Q2 Anon-renewableenergysourcecannotbe replaced. Identify which list below contains only non-renewable energy resources. A coal, oil, sunlight, wind B natural gas, sunlight, wind, tidal energy C oil, uranium, sunlight, tidal energy D natural gas, coal, oil, uranium Q3 The change of state from gas to liquid represents: A the changes taking place as the water level in a lake decreases in dry weather B the change that takes place in saturated air as it cools C the change that takes place in leaves of trees with the Sun shining on them D the change of state necessary for water to be able to percolate through soil CCT CCT CCT CCT Q4 If the air temperature increased throughout the world, the rate at which water moves through the water cycle would: A stay the same B decrease C increase D increase in some areas and decrease in others Q5 Aswatergoesthroughthewatercycle again and again, the amount of water on Earth: A increases B decreases C stays the same D varies from time to time Q6 Anexperimenttestingwhetheroxygenin air can be renewed was set up as in the diagram below. The flasks were placed in strong sunlight foraday.Thegascollectedintest-tubeAmade a glowing splint ignite. From the results, you could conclude that: A sunlight turns water into oxygen and carbon dioxide B plants take in oxygen from the air and give out carbon dioxide C plants produce oxygen if they have sunlight and carbon dioxide D all the oxygen in the atmosphere comes from green plants CCT CCT gas Flask A plant, water, carbon dioxide and light Flask B plant, water and light, no carbon dioxide Flask C plant, water and carbon dioxide, no light sunlight CCT 136 PEARSON science NEW SOUTH WALES Glossary Unit3.1 L Atmosphere:layer of gases above the Earth’s surface Coalseamgas:natural gas released from coal by fracking Deposition:the process in which sediments drop out of a moving stream of water, air or ice Erosion:the removal of sediments away from the place of their formation or deposition Fracking:a form of mining in which water and other chemicals are pumped into rocks, causing them to fracture (break) and release the non-renewable resource Humus:decaying plants and animals and their wastes Igneousrock: rock formed by the cooling of molten rock, for example basalt Minerals:substances found in rocks Non-renewableresource: a resource that takes longer than the average human lifespan to be replaced Photosynthesis:the process by which plants use carbon dioxide, water and sunlight to make food Recycling:the process of reusing materials rather than throwing them away Renewableresource: a resource that is always being replaced naturally Resource:something that satisfies a particular purpose or need Sediment:material such as silt and sand that is transported and deposited by water, ice and wind and forms layers on the Earth’s surface. In time it can become compacted to form sedimentary rock Erosion Igneousrock Renewable resource Sedimentaryrock: rock formed by compacting and sticking together of sediments, for example sandstone Weathering:the process of breaking rocks down into smaller pieces Unit3.2 L Biofuel:fuel obtained from plants, agricultural waste or algae Biogas:a gas produced from the fermentation of organic waste, such as waste from sugarcane, and used as fuel Biomass:all plant and animal matter found on Earth Carboncaptureandstorage:the process whereby carbon dioxide gas is isolated and captured for underground storage after coal is burnt Fossilfuels: fuels such as coal, oil and natural gas, formed from the remains of living things buried millions of years ago Geothermalenergy: energy sources from heat below the Earth’s crust Greenhousegas:gas that traps heat close to the Earth’s surface Hydroelectricity:the process of using water falling from a height to turn turbines and generate electricity Non-renewableenergy source: a source of energy that cannot be replaced after it is used, such as oil or coal Nuclearfuel: a material that can be used $:$N62pthTJksVXp/5txS+MH1HD31sDjfpl/nwHRQSsUiD5HW1BNgtcOm8/kHgeXYjUgKl9mGmcNCF7
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$:$cribe how the humidity inside the bag would have changed during the 24 hours of the experiment.  3 Propose how this change in humidity could have affected the amount of water collected.  4 Demonstrate how the information you have collected relates to the water cycle.  5 Predict how much water you would collect after two or more days. If your teacher agrees, carry out an investigation to test your prediction. The PEARSON science NSW 7 package Go to icon Go to icons are used to make important links to relevant content within the student book and to the next student book in a stage. Agriculture In Australia, a large proportion of the total land area has been cleared of native vegetation (the plants that usually grow there). The land is now used to graze animals or to grow crops such as the wheat seen in Figure 5.4.7. These agricultural areas provide very different habitats from the native vegetation. Fertilisers and pesticides used on the crops may wash into rivers from the farmland, causing changes in river and wetland ecosystems. Scientists have developed new varieties of crops and breeds of animals better able to cope with Australian conditions. Scientists have also developed ways of growing consistently good quality fruit and vegetables that can be produced as cheaply and quickly as possible. Salt-tolerant wheat In parts of Australia soils have a high salt content. The salt occurs naturally, but some land management practices have brought the salt closer to the surface. Not all plants can grow in salty soils and as the area of salty land increases the amount of food produced decreases. If salt reaches the leaves of wheat, the plant cannot carry out photosynthesis. Durum wheat, shown in Figure 5.4.8, is used to make pasta and couscous. Durum wheat is particularly sensitive to salt and about 69 per cent of Australia’s wheat-growing area is affected by salinity. In 2012, Australian scientists from the University of Adelaide produced a variety of durum wheat that is able to grow in soil with high levels of salt. The scientists 5.8 5.9 Vast fields of wheat cannot provide the same habitats as those provided by native vegetation. Figure 5.4.7 created the new variety by using two varieties of wheat as the parent plants and growing plants that have characteristics of both parents. The parent plants used were: • a modern variety of durum wheat that produces a large amount of grain—it has a high yield. • an ancient wheat variety that has the ability to remove the salt from the water as the water moves from the roots to the leaves. However, the old variety has a low yield. The new variety of wheat scientists have created has characteristics of both parent plants. The new variety has both the high-yield characteristic of modern wheat, and an ability to tolerate salt. It has taken about 15 years of research to create this new variety. Now that scientists have been successful in making salt-tolerant durum wheat, they hope to use this knowledge to create a variety of bread wheat that is able to grow in salty soils. Durum wheat is used to make pasta. Its yield is very low when it is grown in salty soils. Figure 5.4.8 Droughtmaster cattle Cattle are not native to Australia and most were imported from Europe. The conditions in Australia are very different from Europe and farmers often struggled to keep their cattle in good condition for the beef market. In the early 1900s, pioneer cattle breeders in North Queensland saw a need for cattle that: • could tolerate hot weather • could make best use of the limited nutrition provided by the native pasture grasses • could walk long distances to access water and feed • were resistant to ticks • produced good quality meat • give birth to their calves easily. Habitats and interactions 213 88 PEARSON science NEW SOUTH WALES Animals are a renewable resource because they reproduce. Figure 3.1.6 Airasaresource Air is a mixture of gases and suspended particles such as dust, smoke and water droplets. The main gases in air and their importance to life on Earth can be seen in Table 3.1.1. Table3.1.1Gasesintheair Gas Percentage inair Importancetolife Nitrogen 78% Provides nutrients for plants to make proteins and other chemicals, which humans and other animals can use as food. Oxygen 21% Essential for most living things, to release energy from food for their bodies to use. Carbon dioxide 0.03% Essential for plants to make their own food by photosynthesis. Other gases such as ozone, water vapour and argon 0.97% Many uses depending on the gas. • Ozoneshieldshumans from ultraviolet rays (reducing our risk of skin cancers). • Watervapourispart of the water cycle that carries water around the planet. • Argonisusedinlight globes. Air:arenewableresource About 21% of the air is oxygen gas. Oxygen is constantly being used by animals and plants but is also constantly being replaced by plants. Green plants, like the one in Figure 3.1.7, use the energy from sunlight, carbon dioxide and water to make their own food. The process is called photosynthesis. As well as producing the plant’s food, photosynthesis also produces oxygen. This production allows the oxygen in the atmosphere to stay at about the same level. Scientists describe the movement of materials from one place to another and back again as a ‘cycle’. Oxygen cycles through the Earth’s atmosphere, soils, rocks, water and organisms.. Green plants use carbon dioxide, water and energy from sunlight to make their food (sugar) by the process of photosynthesis. Figure 3.1.7 Earth’s fragile atmosphere The atmosphere is the very thin layer of air around the Earth’s surface. The first astronauts who ventured into space were amazed at how thin and fragile the atmosphere looked from space. Many said it made them think very deeply about the damage humans are doing to the atmosphere. xi ]]></TextData></Page><Page><Page_no>14</Page_no><display_no>xii</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The verbs below, based on Bloom’s Taxonomy, appear in bold text throughout this book. The verbs help students know the level of response required for a question. The verbs in black are consistent with the key verbs used in NSW syllabuses and examinations. The verbs shown in blue in this list may also feature throughout the book and are provided for additional support to teachers and students. Remembering enter Place data into a computer program by key strokes or copying from a digital source, e.g. CD, DVD, USB storage device label Add annotations to a diagram or drawing list Write down phrases or items only without further explanation name Present remembered ideas, facts or experiences present Provide information for consideration recall Present remembered ideas, facts or experiences record Store information and observations for later specify State in detail state Provide information without further explanation Understanding account Account for—state reasons for, report on. Give an account of—narrate a series of events o$:$htkhwXGa4ghbCwjsnEBHngafljPv+zEsFMEHhR4ykq/BENNB9iD50uFKcwPZfP6jVGFn5dO47p8t
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VkQFh1ddlw==$:$ and what we as humans should do to control it, has also split society into those who believe that it is happening and those 2 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>19</Page_no><display_no>3</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[who don’t. There is even debate among those who do believe it is happening: some believe that it is caused by human activity, while others believe it could be part of a natural cycle. Whatever its cause, glaciers like the one in Figure 1.1.1 are melting at a higher-than-normal rate. Older issues, such as whether nuclear power should be used in Australia, are being debated again because of our increasing energy needs. As a future adult and voter you will need an understanding of science to help you decide what we should do about these issues and any new issues that arise. To make good decisions about our future, you will need an understanding of science. The branches of science The subject of science covers many different areas, ranging from acids to aardvarks, electricity to emus, rats to rocks, Venus to viruses, and much, much more. Science covers so many different areas that it must be split into different branches or disciplines, some of which are shown in Figure 1.1.2. Scientists tend to work in one particular branch of science. This allows them to explore it in detail and develop a deep understanding of it without being distracted by what is going on in the other branches. Climate change: do we believe the evidence that temperatures are rising because of human activity or do we reject it based on other evidence? Figure 1.1.1 The main branches of science Figure 1.1.2 Astronomy is the science of the planets, stars and the universe. Chemistry is the science of materials, chemicals and chemical reactions and how they might be used. Geology is the science of rocks,$:$t0LmcriUW09u7LA9zjUq1chsaDpdqSd7roxngtJZ472SiMUxejR4ME0MDPtk/96Vp3chOiU/TuI/
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CMehuHzz$:$nology) and fish (ichthyologists study ichthyology), as shown in Figure 1.1.3. The many branches of science There are lots of other very specific sub- branches of science. Some are teuthology (the study of octopuses), mycology (the study of fungi), chiropterology (the study of bats), carpology (the study of fruits and seeds) and oology (the study of eggs). Teamwork Science requires teamwork. In the laboratory, you will frequently work as part of a team, particularly when doing experiments or research. Everyone is good at something and not as good at something else. Working in a team allows you to pool everyone’s talents. Scientists usually work in teams too. As Figure 1.1.4 shows, some teams have only a few members. Everyone is good at something and not as good at something else. By working as part of a team, scientists can share their skills. Figure 1.1.4 The branches of science are split into smaller sub-branches. Some of these are then split into even smaller sub-branches. Figure 1.1.3 Science Astronomy Biology Chemistry Ecology Geology Psychology Physics Some sub-branches Microbiology (germs, bacteria, viruses) Botany (plants) Zoology (animals) Seismology (earthquakes) Palaeontology (fossils) Vulcanology (volcanoes) Petrology (rocks) Acoustics (sound) Optics (light) Mechanics Entomology (insects) Arachnology (spiders) Ichthyology (fish) Branches Prac2 p. 9 Prac1 p. 8 4 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>21</Page_no><display_no>5</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Some common tasks All scientists carry out the same basic tasks regardless of what team they are part of or which branch or sub- branch of science they investigate. All scientists: • make observations and measurements • make inferences and predictions about what is happening and what might happen in the future • analyse their measurements, construct tables and keys, plot graphs, make calculations and look for patterns • make models to help them understand what is happening • classify objects into groups of similar things. Unit 6.1 becoming extinct. The possum lives in the mountains of the Kosciuszko National Park. In summer and autumn it eats Bogong moths, beetles, millipedes and spiders, and sometimes the seeds of plants. In winter, it hibernates, sleeping under a cover of snow that insulates it from the freezing cold. You can see it in Figure 1.1.5. To protect the possum, scienti$:$rPKFZHBpEUMfLx4175ef/+XJcC/j1KtHTv2fvDYixcdF7dwz7MgEewu+KM0SQ6MEVQD/yQy0+jkU
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rzQVQZ3CkPsRAsWrMKY=$:$ (Burramys parvus) left in NSW. The species is classified as endangered and scientists are working to prevent it from Figure 1.1.6 Zoologists determined that foxes and feral cats were eating the possums. Ecologists need to find out whether the possums are being affected by the area being divided up into smaller and smaller parts by the local ski industry. Botanists need to find out whether bushfires are damaging the plants whose seeds the possums eat. Chemists need to confirm whether the levels of arsenic in local Bogong moths and possum faeces is consistent with natural background levels or caused by chemicals used on farms. Climate scientists need to find out whether less snow and a higher snowline will affect the possum’s survival. ADDITIONAL Big problems require teamwork across different branches of science Working scientifically 5 ]]></TextData></Page><Page><Page_no>22</Page_no><display_no>6</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Science and the law The observations that scientists gather and the conclusions they make form the basis of many of the laws and regulations that we all must follow every day. Laws make you wear a bike helmet because science has shown that helmets can protect you from serious head and brain injury. Figure 1.1.7 civics and citizenship The CurrICuLum LeArNINg ACrOss For example, scientific evidence on car and bike crashes has led to speed limits, and laws that make us wear seat belts in cars and helmets when riding a bike or motorbike (Figure 1.1.7). In a similar way, scientific evidence on bushfires has led to laws determining days of total fire ban and the types of houses that are built in areas of high bushfire risk. Scientific evidence has also been used to form laws and regulations that: • make car manufacturers include airbags, crumple zones and crash-resistant fuel tanks • control the type of houses built in areas at risk of floods or cyclones • determine which drugs should be illegal, which should be available on prescription and which can be bought at the supermarket • control the additives that can be put in food • control how long food can be sold for (‘use by’ and ‘best before’ dates) • determine unsafe levels of sound, chemicals and dust for workers • control the type and amount of pollutants that can be released into rivers, soil and the atmosphere • preserve animals, plants and landscapes at risk of being lost forever. Sometimes, scientific evidence leads to changes in global laws. For example, chemicals called chlorofluorocarbons were destroying the ozone layer,$:$DefDN0BVm2+KbF/padVqtoZwbWeK4d284adlKIKrL+ftrERyLEKYiQlwmBAxHIKEkDVdjlh9267Z
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ul/4wiK4Nop91p6zVhOWNKTHc2BIpDduhLisjMsT$:$ why. 4 Propose a reason why laws now determine the type of houses that are allowed to be built in areas at risk of cyclones or bushfires. 4.61.1 6 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>23</Page_no><display_no>7</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Remembering 1 Name: a devices that have only been around in the last ten years b a scientific issue that has arisen in the last ten years. 2 List seven important branches of science. 3 List four sub-branches for each of: a biology b geology c physics. Understanding 4 Explain why everyone needs to have an understanding of science. 5 A biologist usually specialises in one sub-branch of biology. Explain why. Applying 6 Identify the branch (or branches) of science being investigated in the science4fun on page 2. 7 Identify the branches of science that are being studied below. a Amanda is measuring the amount of pollution in a lake. b Sarah is making a video of a volcano erupting. c Brian is studying the movement of the planets. d Yang is measuring the speed of sound. e Joe is testing what an acid does to metal. 8 For each of the following investigations, identify the branch and sub-branch that is being studied. a Abdul is counting how many eggs a cockroach has laid. b Hon is studying the crystals embedded in a rock. c Travis is investigating how light bends as it passes through glass. d Lisa is photographing the bones of a dinosaur. e Francesca is measuring the growth of a seedling. Analysing 9 Compare the similarities and differences between the types of work done by a detective and a scientist. 10 Refer to the contents pages (pages v–vi) and classify each of the chapters as biology, chemistry, physics, geology or astronomy (space). Evaluating CCT 11 Some branches of science cover two or more other branc$:$M/o3uTHN+LaPyMhgc/a4gPYHGi3+LH33LFEfnbHWMs1unwVLlIM7xbR7K9x4SnnfHxMM02pfr8Qi
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Y22mhgE=$:$to: • state what resource management is • list different types of resource management • list the branches of science that might be involved. b Investigate the NASA website to find the branches of science that might be involved in space exploration. Present your findings as a series of dot points. CCT L ADDITIONAL Unit review1.1 Working scientifically 7 ]]></TextData></Page><Page><Page_no>24</Page_no><display_no>8</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations1.1 Potato sprouts Purpose To determine if plants respond to light. Materials • old potato (with sprouts) • handful of potting mix • 1 cardboard box (such as a shoe box or cereal box) or cardboard to make one • 2 pieces of cardboard • sticky-tape • scissors Method 1 Adapt your cardboard box so that it has a lid like a shoebox. This may require taping up its original lid and cutting out a new one. 2 Puncture a small hole in one end of the box and expand it until it is 1 to 2 cm in diameter. 3 Cut three or four small cardboard ‘walls’. Tape them i$:$Te43sYxqvAFRMWifaens/01YTAl8dimdL3tvq5QaYnyRyrAEyxuxPbYBeiWV7U5/vTM79mgIBJ4/
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uuiDC7z4j0Hm/A==$:$e your finger and record what you see. Results Record all your observations in your workbook. Practical review 1 Assess how well you followed the instructions for this prac. 2 Propose a reason why: a it was almost impossible to blow up the balloon without the pinhole. b the pinhole allowed the balloon to inflate. c a blocked pinhole kept the balloon inflated. d water rushed out of the balloon when your finger was removed from the pinhole. soft-drink bottle small hole block hole with finger balloon air water Figure 1.1.9 Working scientifically 9 ]]></TextData></Page><Page><Page_no>26</Page_no><display_no>10</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The laboratory is where scientists carry out experiments and make observations and measurements. The type of laboratory used by different scientists depends on what they are studying. For many, the laboratory is outdoors. F$:$J/USZuYRRL4P040AvWv+Wee74cqw3V5WXL03XTslzpOUPiigdSFw6dRxuyBx1UMH4aQwYxQ1Hn1V
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z+j1JPIDSALZmBC0wfaF59Qmcw==$:$s A scientist works in a laboratory. Laboratories are where scientists run most of their experiments and make most of their observations, measurements and discoveries. Your idea of a laboratory is probably a large room equipped with Bunsen burners, sinks, glassware, balances and chemicals and occupied by people in white coats and safety glasses. This is the type of laboratory that chemists tend to work in and the type of laboratory that you will eventually work in at school. It might look something like Figure 1.2.1. To most of us, the laboratory is a place full of Bunsen burners, glassware and people in white coats. Figure 1.2.1 10 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>27</Page_no><display_no>11</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Different scientists have very different ideas about what a laboratory is. For marine biologists, the laboratory could be a coral reef. The laboratory of a zoologist might be a rainforest, and a laptop computer and video camera could be their most important equipment. The laboratory of an astronomer will be wherever their telescope is mounted. Figure 1.2.2 shows a palaeontologist at work in his laboratory. Scientists like him will usually have another laboratory in which they can test the samples they collected outdoors. For example, an ecologist might collect samples of polluted water from a creek but then analyse them back in their other laboratory. For palaeontologists, the laboratory could be the site at which a dinosaur skeleton has been found. Their equipment is likely to be a spade and brushes to clear the soil away from around the bones. Sturdy boots, overalls and perhaps a hat will be $:$RdmRtg0oIxAaW1Tu3mW97LVN3JS4zh63N1X8HFI0seOEel/eQG69qNVicU7Uz9dBDitUtyvidm6S
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a+Xj8aJFwC/A5xEtyx9KaikC00xpYlh98QeMjI+m4zUAiS/LgA==$:$rrent, and ecologists need pH meters to determine how acidic creek water is. However, there is a set of equipment common to most laboratories, including the ones at school. Glassware Glassware such as beakers, conical flasks, test-tubes and watch-glasses allows you to mix and heat chemicals. Most glassware in the laboratory is made of Pyrex, a special type of glass that is less likely than normal glass to crack when it is heated or cooled. Some common pieces of equipment are shown in Figure 1.2.3. Beakers and conical flasks usually have markings up their sides, but the markings only indicate rough volumes.You would use a measuring cylinder to measure more accurate volumes.Volume is normally measured in the laboratory in millilitres (unit symbol mL). Larger volumes are measured in litres (unit symbol L). 250 200 150 100 50 110 100 90 80 70 60 20 30 40 50 10 250 mL 200 150 100filter funnel watch-glass conical flask test-tubes test-tube rack measuring cylinder beaker spatulas safety glasses Equipment commonly used in the laboratory Figure 1.2.3 Working scientifically 11 ]]></TextData></Page><Page><Page_no>28</Page_no><display_no>12</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Balances The beam balances, electronic balances and spring balances shown in Figure 1.2.5 can all be used to measure the mass of an object. Mass is a measure of how much matter there is in an object. In the laboratory, mass is usually measured in grams (unit symbol g) or kilograms (kg). Reading a meniscus A meniscus is the curved shape formed by the surface of a liquid where it contacts another surface. The meniscus is easy to see when the liquid is in a tube such as a measuring cylinder. Sometimes the meniscus curves upwards and sometimes it curves downwards. This could make measuring volumes a little difficult. Figure 1.2.4 shows how scientists measure the volume when a meniscus is present. Measure from the bottom of the meniscus if it curves downwards. Measure from the top of the meniscus if it curves upwards. The surface of a liquid in a measuring cylinder forms a curve called a meniscus. Figure 1.2.4 spring balance electronic balance beam balance Different balances can be used to measure the mass of an object. Mass is sometimes incorrectly called weight. Figure 1.2.5 Heating equipment Hotplates and Bunsen burners are some of the most important and dangerous pieces of equipment that you will use in the school laboratory. Both get extremely hot and so can burn you seriously if you use them incorrectly. Parts of the Bunsen burner Figure 1.2.6 shows the parts of the Bunsen burner. The collar controls the amount of air that enters the burner and controls the heat and colour of the flame. If you shut $:$a4asbZfpWdaMOhcFtzkHNW6AwpNaHF5oPVEx0fQouyBJGPIqvTYusbIbSr5Pf9Hj36W7JDzWF2gH
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VG78hH5ZBLL9x8zQUwx2btth5Up9h+6jWVpwjlg+4LTSJE53Y7Q=$:$se of the flame, there is a small cone of unburnt gas. As Figure 1.2.7 shows, the hottest part of the flame is just above this cone. barrel collar base gas hose airhole (gas jet inside) Prac1 p. 17 Prac2 p. 18 The Bunsen burner Figure 1.2.6 12 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>29</Page_no><display_no>13</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Other equipment used for heating A kitchen stove isn’t very useful unless you have frying pans, saucepans, tongs and stirring spoons to help you cook the food safely. A Bunsen burner also needs additional equipment to help you heat objects and to keep you safe. Some of this equipment is shown in Figure 1.2.8. hottest part of flame cone of unburnt gas The blue flame is: • hot • clean • difficult to see. The yellow flame is called the safety flame. It is: • relatively cool • dirty • highly visible. The yellow flame is easy to see and relatively cool. The blue flame is much hotter and almost invisible. This makes it much more dangerous. Figure 1.2.7 Tongs and pegs: allow you to pick up hot objects Clay triangle: used to support a crucible Gauze mat: used to spread the heat Tripod: used to hold beakers above the flame Retort stand, bosshead and clamps: used to hold other equipment Crucible and lid: used to burn small samples of solid Evaporating dish: used to evaporate off the solvent from a solution, leaving crystals behind Bench mat: used to protect the bench The hotplate and Bunsen burner need additional equipment to make them useful. 4.61.2 Figure 1.2.8 Heat$:$o198CVDDJDTWC0w9LmThScJoJHNTCIGdrkIYMBzVDHdB+T92alM0GWUZZXOZ7YsXpKP5qMqpt510
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zEFn7dZd$:$unsen burners are hot. Your sign must be in two colours only and use no words. Inquiring 1 Fire blankets, eyewashes and fume hoods are common safety equipment in the laboratory. For each, find: • an image • what it is used for • how it is used • its location in your science laboratory. a d e b c Present your research as a plan of the laboratory with attached images and descriptions. 2 Research the person named Bunsen, after whom the burner was named. • Find his full name, dates and locations of birth and death. • Determine what he had to do with the burner. Present your findings on an A4 sheet. Only include relevant information. science fun Fake wounds Can you fake an injury? Collect this… • small ball of coloured dough from your teacher • small amount of bright red food dye • knife or bamboo skewer • small twigs, cotton wool and bandages Do this… 1 Pat your lump of dough until it is flat. 2 Pat it onto your skin and blend it in to your skin by squashing its edges down with your fingers. 3 Use the skewer or the blunt edge of a knife to make a fake ‘cut’ in the surface of the dough. Be careful when handling the knife—get supervision from an adult. 4 Make the wound look more realistic by inserting a small twig into the ‘cut’ and by dribbling some red food dye into it. 5 Use paper towelling, cotton wool or bandages to disguise the edges of the dough. Record this… Describe what the cut looked like. Did it look realistic? Explain what you should do if someone really cuts themselves in the laboratory. 16 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>33</Page_no><display_no>17</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[1.2 Practical investigations The Bunsen burner Purpose To light a Bunsen burner and produce a yellow flame and a blue flame. Materials • Bunsen burner, bench mat and matches • pin Procedure Copy the table in the results section into your workbook. Part A: Lighting the Bunsen burner 1 Follow the instructions in the skill builder to light a Bunsen burner. 2 Turn the collar to open and shut the airhole. Observe what colour flames are produced. 3 Turn off the Bunsen burner and allow it to cool. Part B: Unburnt gas 4 Push a pin through the wood near the top of an unlit match. Balance the match on the top of the Bunsen burner so that the match head is in the centre of its barr$:$VFSp77MAQ5L3MnqCI5zyf9R3KlYWGBcYEqpb6wqEPzKF3HR4OquPpTUNaKZ7uewec1C3agEcksKg
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$:$y to another. 4 Compare the original story with the story that it ended up being. Record this… Describe what happened. Explain why you think this happened. Communicating1.4 Tables Measurements and observations are easier to read and analyse if they are displayed in tables. Tables also make trends (patterns) in the measurements more obvious. Each column in a table needs to have a clear heading that includes the units in which each measurement has been taken. Computer programs such as Excel allow you to produce an electronic table on a computer. This type of table is known as a spreadsheet. Graphs A graph shows trends in measurements even more clearly than tables do. The type of graph you draw depends on the types of observations you make. Bar and column graphs Some observations fall into discrete groupings. This means that all the observations can be sorted into categories and counted. Animals, for example, fall into discrete groupings like kangaroos, ants, cockatoos and sharks. Other observations that have discrete values are makes of cars (such as Holden, Toyota, Ford, Mazda), Working scientifically 27 ]]></TextData></Page><Page><Page_no>44</Page_no><display_no>28</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Pie graphs Discrete groupings are also used to construct pie graphs or sector graphs. A pie graph shows the proportions of each grouping within a total. In a pie graph, the whole pie represents 100%, half the pie represents 50% and a quarter-pie represents 25%. As an example, Figure 1.4.2 shows the percentages of different animals living in a nature reserve. Line graphs Measurements involve numbers that are not discrete but continuous. This means that if you choose two numbers, then you can always find other numbers in between them. For example, between 10 and 20 you will find the numbers 11, 12, 13, 14 and so on. Between them are even more numbers such as 11.4, 12.7 and 13.576362. Therefore measureme$:$NyUzLS+3/pbEmI6usDuosxy0+NCJpeHVpqpW+bsl/C/tu+dfw195T4cCTmnEn84sYgarYwehuEVT
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JhrMoaMOMOmQlg3g$:$the curve is called a curve of best fit. These ‘best fits’ clearly show patterns that might exist in the measurements you took in the experiment. An example is shown in Figure 1.4.4. Wallabies 17% Possums 9% Birds 10% Spiders 6% Insects 29% Lizards 29% This pie graph shows the proportions of each animal in a nature reserve and not their real numbers. Figure 1.4.2 Prac1 p. 32 Prac2 p. 33 1.8 sports (netball, football, golf, tennis), building materials (timber, brick, concrete, glass) and the sex of people (male or female). Bar and column graphs are used when you have a set of observations that are discrete, such as the data in the table below. These discrete values are displayed on one of the axes of the graph while numbers are displayed on the other axis, as shown in Figure 1.4.1. Axes are the horizontal and vertical lines ‘framing’ the graph. Cause of spinal injury Average number injured per year Car crashes 164 Falls 136 Sports 24 Surfing 20 Diving 20 0 20 40 60 80 100 120 140 160 180 Column graph Numberinjuredperyear Car crashes Falls Sports Surfing Diving 0 20 40 60 80 100 120 140 160 180 Bar graph Number injured per year Car crashes Falls Sports Surfing Diving There are five main causes of injuries to the spine. These two graphs indicate how many Australians are injured on average per year. Figure 1.4.1 28 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>45</Page_no><display_no>29</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Age of mouse (days) Mass (g) 0 5 2 15 4 22 6 25 8 27 10 28 Scientific reports Scientific reports are used by scientists to communicate to other scientists how they performed an experiment and what they found out in it. If you set out your report clearly and logically, then other scientists will be able to repeat your experiment. Temperature(˚C) Time (min) 10 20 30 40 50 60 70 80 90 100 0 1 2 3 4 5 6 7 8 9 10 A line of best fit is drawn roughly through the middle of all the points. In this way, the line of best fit shows the trend or pattern in the graph. Figure 1.4.4 Age (days) Mass(g) 0 2 4 6 8 10 5 10 15 20 25 30 Line graphs need two sets of numbers to plot. Figure 1.4.3 Purpose The purpose or aim is what you wanted to do in an experiment or practical activity, what you wanted to show or wanted to prove. Hypothesis You probably have some idea of what might happen in an experiment even before you start it. This ‘educated guess’ is called your hypothesis. A hypothesis is an inference based on what you already know. A hypothesis is not always included in a scientific report. Materials This is a list of all the important equipment, chemicals and materials that you used. If equipment comes in different sizes, then make sure you include the size you used (for example, 250mL beaker). Procedure The procedure or method is a detailed list of what you did in the experiment. You must include what quantities were used (for example, 5g, 2 spatula loads or 10mL), and the exact order in which the steps of the experiment were performed. A diagram of the experiment is a useful way of showing what you did. $:$Dr9sekRom08Ov2x6RGibT9yeHEyW45F4fcBy0EPmZ6Emzwck0HKz5NSG6A+fUnOUNBwlYr5HWsF7
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DQ==$:$ 1.5.2 Plotting a graph When plotting a graph, you first need to decide which type of graph you are to plot. Line graphs are used when you have two sets of continuous measurements. The results from the ball-drop experiment have two sets of numbers and so a line graph is the most appropriate graph to plot. It might look like the one in Figure 1.5.3. In this example, a column, bar or pie graph would make no sense. Bar graphs are used when one set of results is discrete. For example, bar graphs would be a good way of showing the way bounce height changed when the type of ball or type of surface was changed. Your conclusion Your conclusion must answer the purpose or aim of your experiment. Depending on what you tested, an appropriate purpose and conclusion would be: Purpose: To test what increasing drop height does to bounce height. Conclusion: Increasing drop height causes bounce height to increase. Two sets of measurements require a line graph. Figure 1.5.3 Bounceheight(cm) Drop height (cm) 200 150 100 50 0 50 100 150 200 250 1.9 Prac1 p. 38 36 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>53</Page_no><display_no>37</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review1.5 Remembering 1 Recall variables by matching the different terms with their definitions. Dependent variable Kept the same Independent variable Changed during the experiment Controlled variable What you are measuring 2 In the science4fun activity on page 34, sharp pencils were stabbed into a plastic bag full of water. For this activity, state: a an aim b a hypothesis. 3 List variables that are likely to affect the: a amount of sugar that will dissolve in a cup of tea b number of visitors to a swimming pool c growth of a plant d time taken to cook a potato e number of times you go to the toilet in a day. Understanding 4 Explain why only one variable should be changed in any single experiment. 5 Explain why you should try to collect five or more results in an experiment. 6 Georgie heard an old tale that if you want an avocado to ripen quickly, then it should be placed in a brown paper bag with a banana. She thought this sounded weird and wanted to see if it was true. Describe in detail how she could test if the tale was true or not. Applying 7 Identify which of the following sets of drop heights would give the best idea of what happens when drop height is increased. A 10 mm, 20 mm, 30 mm, 40 mm, 50 mm B 5 cm, 10 cm, 15 cm, 20 cm, 25 cm C 50 cm, 100 cm, 150 cm, 200 cm, 250 cm D 10 m, 20 m, 30 m, 40 m, 50 m 8 Identify likel$:$15Y0g8q94JnNv6zYJIsmTzubaRMmYB0r6+BzAbmEXsmkCm3dNUdxv5JO9D5saPOz9XIuxEmB+gJw
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3jeMlTVhdalg0E2R$:$er than tennis balls. a State the dependent variable that Bob tested. b Identify how many variables Bob changed during the experiment. c Assess whether the experiment was a fair test. d Do you agree with Bob’s conclusion? Justify your answer. Creating CCT 11 For the experiment in question 9 or 10, design an experiment that would test a single variable. Inquiring Scientific investigations are regularly reported in the newspaper, on websites and in scientific magazines such as Cosmos and Scientific American. Find an article that discusses a scientific investigation and: • give the names of the scientists involved • summarise what they found out. Present your information in whichever way you choose. Working scientifically 37 ]]></TextData></Page><Page><Page_no>54</Page_no><display_no>38</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[sTuDeNT DesIgN Practical investigations1.5 Planning your own investigation Purpose To design and run an experiment that tests a single variable. Materials Choose your own, depending on your choice of topic. Procedure 1 List the variables that are likely to affect the: • bounce height of a ball • amount of sugar that can be dissolved in a cup of tea • adhesive strength of sticky-tape • stretch of an elastic band or another elastic material such as stockings • strength of paper. 1 sAfeTy A Risk Assessment is required for this investigation. 2 Choose ONE of the above topics and design an experiment that will test ONE of its variables. In your workbook, write a hypothesis that describes what you expect when you change that variable. For example, ‘We expect that a tennis ball will bounce higher than a soccer ball when dropped from the same height.’ 3 Write your procedure in your workbook. 4 Before you start any practical work, assess your procedure. List any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedur$:$ELD1smnROZEaRfHmPG3XfM9cRMWXcp+4GQ1rg+ek36jxDYJW9KTKyYzrM3h2sHV2D8i3K4pNmNgd
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g8xBZ+3WXQ==$:$ numbers Unit 1.4 L Aim: what you are trying to do Analysis: looking for trends in the results Bar graph: used when one set of observations is discrete. Bars are horizontal Column graph: used when one set of observations is discrete. Columns are vertical Conclusion: what you have found out Discussion: analysis Hypothesis: educated guess Line graph: used when there are two sets of continuous measurements Method: tells how you did the experiment Pie graph: used to show proportions. Also known as a sector graph Procedure: tells how you did the experiment Purpose: aim Results: the measurements and observations made in an experiment Sector graph: used to show proportions. Also known as a pie graph Unit 1.5 L Controlled variables: held constant throughout an experiment Dependent variable: will change naturally as you change the other variables Fair test: changing only one variable at a time Independent variable: what you change in an experiment Variables: factors that influence an experiment Column graph Line graph Working scientifically 41 ]]></TextData></Page><Page><Page_no>58</Page_no><display_no>42</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[2 Properties of substances • describe matter in terms of particles • outline how particle movement is related to energy • use the particle model to predict what happens when different states of matter are heated or cooled • explain how the physical properties of matter change during changes of state • explain density in terms of the particle model • identify the benefits and limitations of using models to explain solids, liquids and gases CCT ADDITIONAL • research how Aboriginal and Torres Strait Islander peoples use the physical properties of natural materials in everyday life AHC • investigate how the chemical properties of a substance affect$:$Uwd5T0/3S6EzyzwT3/lGs7AbbhalUg0SQAUlFFis0yv1uunEMrrOiEOgKBG4h+JUEdUqJlh06BM6
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Z/6W$:$ liquids and gases appear so different? • why clothes dry even when it’s not hot? • why you breathe out fog on a cold morning? • why icebergs float? 42 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>59</Page_no><display_no>43</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Physical and chemical properties2.1 There are millions of different substances in the world. Each can be identified by its properties. Properties describe a substance and how it acts. They include its appearance, what it does when heated or cooled, and how it reacts with other substances. science fun What is foam? Is shaving foam a solid, a liquid or a gas? Collect this … • can of shaving foam • plate (not paper) • small mass (such as a 50c coin or a pebble) Do this … 1 Squirt a blob of shaving foam onto the plate. What does it look like? Does the foam flow or change shape without being pushed around? 2 Place the small mass on the top of the foam. Does it stay there or does it sink? 3 Squirt another blob of foam onto the plate. Put the plate into a cupboard so that it won’t be touched. Leave it there overnight. What does the foam look like the next day? Record this … Describe what happened. Explain why you think it happened. Physical properties You can probably tell which objects and substances around you are solid, liquid or gas by the way they look and act. What you see are physical properties. Testing a substance for its physical properties doesn’t destroy the substance, or change it into anything new. Some of the most useful physical properties of a substance are: • whether it’s a solid, liquid or gas at room temperature (norma$:$XyRpN7bn052vyMBY74AihYvzMPthtZicrRasPugVmnUOq2HO2YEdWCbWugy5niX5zfrZGvKLXvLS
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kqCfZEStQYXiqhgnRjHbSJQ/dtJgik+fRbbSOanV67rzhD1m/zoBFfODCKy+Xb7Q$:$s have developed biodegradable plastics from plant-based substances but these plastics are more expensive than similar oil-based plastics. They can’t be recycled and cannot be used for long-term packaging. For these reasons, their use is not yet widespread. Most plastics are non-biodegradable but many can now be recycled. This reduces waste and stops their chemicals from polluting the environment. Figure 2.1.8 revieW 1 List four biodegradable and four non- biodegradable substances. 2 Describe the evidence that shows that fruit and cardboard are biodegradable. 3 A log in the forest grows mushroom-like fungi on it. a Use this information to classify the log as biodegradable or non-biodegradable. b Predict what will be left of the log after 10 years. 4 Classify faeces (poo) as biodegradable or non-biodegradable. 2.2 Most plastic bags are non-biodegradable and so they don’t rot away. If they get washed into rivers and the ocean, wildlife like this bird can get caught up in them and can die. Figure 2.1.9 ADDITIONAL 48 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>65</Page_no><display_no>49</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review2.1 Remembering 1 State an alternative term for states of matter. L 2 List the three states of matter commonly found on Earth. 3 State whether the following are solids, liquids or gases. a a sugar cube b ink c air 4 List the different states in which different substances exist in the following mixtures. a soft drink b chicken curry c mud 5 List two physical properties and one chemical property of a sheet of paper. 6 Shaving foam cannot be classified as a solid or a liquid because it has some of the physical properties of both. List the physical properties of shaving foam that could be used to classify it as: a a solid b a liquid. Understanding 7 a Explain why plasma is usually found in stars but rarely on Earth. b Describe the conditions on Earth that are required for plasma to form. 8 Define the terms: L a compressed b incompressible c odour. 9 Explain how the compressibility of gases makes them ideal for using in shock absorbers in the suspension of cars and bikes. 10 a State what causes humidity. b Describe what a humid day feels like. Applying 11 It is easier to list$:$8SGAPh14pvQuE/ve3cFfLCwogwkyO4Yul8G0bOr8ktrSiXnb+dv/FhsDFagdIqVSD/Vx89rG9z26
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c2BIpPud4w5E5aRpaSk9BS0+HMM=$:$id doesn’t spread across the surface. Inquiring ADDITIONAL Aboriginal and Torres Strait Islander peoples have AHC long used the physical properties of the natural materials around them to create items used in their everyday life. Research some of these materials. Some you might look at are: • waxes and resins used as glues • saps, barks, oils, leaves and fruit used for bush medicine • bark, timber, leaves and fronds used for utensils, shelter and housing • plant fibres and animal sinews used for string and rope • stones, bones, shells, teeth, branches and roots used for tools, weapons and utensils • stalks and leaves used for weaving baskets. Whatever materials you research, find: • an image or video of the material being used • how their physical properties makes them ideal for their particular uses • whether the use of the material was restricted to a particular region or is/was used Australia-wide. Present your research as a PowerPoint presentation. ADDITIONAL ICT Properties of substances 49 ]]></TextData></Page><Page><Page_no>66</Page_no><display_no>50</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations2.1 Slime Purpose To make slime and observe its properties. Materials Note: PVA tends to change consistency depending on the brand chosen and its age. The quantities of PVA and borax shown below may need to be altered slightly depending on the brand of PVA used. • 10 mL 4–6% borax solution • 25 mL PVA glue • a few drops of food dye • eye dropper/Pasteur pipette • disposable medicine measuring cup • 10 mL measuring cylinder • 2 disposable plastic cups • icy-pole stick • disposable rubber gloves 1 SAfeTy Borax may irritate if it is inhaled or it gets into the eyes or on the skin. Wear safety glasses and rubber gloves at all times. Procedure 1 Use the measuring cylinder to measure out 10mL of borax solution. 2 Use the disposable medicine measuring cup to measure out 25mL of PVA glue. 3 Pour the PVA into a disposable plastic cup, using the icy-pole stick to scrape out the last bits. 4 Add a few drops of food dye to the PVA. 5 Pour the borax solution, all at once, into the cup containing the PVA and food dye. Stir thoroughly with the icy-pole stick. 6 Empty out the slime and rinse it gently under a slow-running tap. 7 Test your slime to find: • if it can be rolled into a ball • what happens when it is stretched • whether it flows to take $:$LFT1GFwMMWII7CiwscNQZYaBZwvbg02NmTugZEptdaYRXPgFfvGYE8MrhzL4BrCiorPpeyoYMjZH
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sPkf4JXc7yzjmMAQyt965w==$:$ slime flow to take the shape of its container? What happens when a ball of slime is dropped? 50 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>67</Page_no><display_no>51</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[STUDeNT DeSIGN Oobleck Oobleck is an easy-to-make slimy goo. Purpose To find a recipe for oobleck and then to make some. Materials To be selected by students. Procedure 1 Search the internet to find recipes or videos that show how to make oobleck. Print or save the recipe and save any video you find. 2 Summarise the main points of the recipe or video and write them in your workbook as your procedure. 3 Before you start making your oobleck, assess your procedure. List any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required materials and start work. 2 SAfeTy A Risk Assessment is required for this investigation. 4 Once you have made your oobleck, test it by: • hitting it with your fist (or prodding it with your finger if you have only a small amount) • slowly lower your hand (or a finger) into it • quickly remove your hand (or finger) from it. • running the tests that were performed on slime in Prac 1. Results Record your results in a table like that used in Prac 1. Practical review 1 List the properties of your oobleck that belong to: a liquids b solids. 2 Oobleck is classified as a ‘non-Newtonian’ fluid. Use the properties found in this investigation to describe a non-Newtonian fluid. The Oobleck of Dr Seuss In the book Bartholomew and the Oobleck by Dr Seuss, a ki$:$QlJ+MA01Vcvzst+M79qXMIkfL8+U5Zrrm5l1jl6Czr+WGlyDa0rjNIQ2tc5makKVRu+zYDI97QbU
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ocOAu/M4p0xm//puuINHiGTzZWdJCaMFbgxlGfo3WBdGEFR1Q/P6M/jfmX4TQKw=$:$ happen in the science4fun activity on page 55 when the bottom of the soft- drink bottle is placed in: a hot water b ice water. Applying 8 Use the particle model to explain why: a solids keep their shape b a gas can be compressed c liquids take the shape of the container into which they are poured d a solid cannot be compressed. Evaluating CCT 9 Barbecue gas cylinders are usually weighed as they are being filled. Propose a reason why. 10 The ball in the science4fun activity on page 52 rises when the container of rice is shaken. Use packing to propose a reason why. Creating CCT 11 Construct a Venn diagram showing which properties are shared between solids, liquids and gases and which properties belong to only one state. Follow these instructions. a Draw a diagram like that in Figure 2.2.11 in your workbook. Figure 2.2.11 gas liquid solid b Identify which of the following properties is shared by all three states and write it in the overlap of all three circles. has energy fixed shape changing shape fixed volume changing volume can be compressed incompressible closely packed loosely packed c Identify the properties shared by two states (for example, solid and gas) and list them in the relevant overlaps. d Identify the properties displayed by only one state and list these in the appropriate spaces. Inquiring 1 Research how LPG is made commercially. Present your findings as a flow chart showing the main steps in its production. 2 Find the main differences between a petrol car engine and a diesel one. Present your research as a table or a series of diagrams that compares the two engine types. Properties of substances 59 ]]></TextData></Page><Page><Page_no>76</Page_no><display_no>60</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations2.2 Liquid thermometer Purpose To build a model thermometer. Materials • water • 2 drops of food dye • Plasticine • 250 mL conical flask • clear drinking straw • permanent marker pen Procedure 1 Set up the apparatus as shown in Figure 2.2.12a. 2 Carefully blow down the drinking straw. Water should rise up it. Stop blowing$:$v4o8Ft3oppPZVUJRb/u7AqnG6B26wGYRO7Vhvr3x2Qux1JyU3wx9Gf9fRDiLPGtmzXM/2LPDr92C
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1QzlVwi5EQjvTQ==$:$rd what happens to the water level. 3 After it reaches the line again, put the flask into a sink of cold water. Record what happens. Practical review 1 Explain what happened in this experiment by copying the following sentences and choosing the correct term. a Adding heat causes liquids to expand/contract. This caused the liquid to rise/drop in the drinking straw. b Removing heat causes liquids to expand/ contract. This caused the liquid to rise/drop in the drinking straw. 2 Thermometers usually do not use water but instead use alcohol (coloured red) or mercury. Propose a reason why. straw Plasticine conical flask a b Figure 2.2.12 60 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>77</Page_no><display_no>61</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Compressing liquids and gases Purpose To determine whether liqui$:$1H4mxgPc1IrlN6qqUX9pRtRDm5cRfqWWQz6gjuDwNMTrx6qjYUY6L5pIuPwOa580U+Fuy+S4UXcp
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IKrwrrsbgA==$:$nge is now full of air (with a little water that will help seal it). Once again, push the nozzle against your finger and attempt to push the plunger down. Observe what happens. Can you compress the air? Practical review 1 Explain your observations in terms of the spacing of particles in liquids and gases. 2 Construct a conclusion for your investigation. STUDeNT DeSIGN Pressure can protect Purpose To design and test a container that uses pressure to protect an egg. Materials • 1 fresh egg (uncooked) • 2 zip-lock bags • 1 drinking straw • sticky-tape Procedure 1 Design: a a container that uses air pressure and the materials listed above to protect a fresh egg when it is dropped onto a hard surface. b an experiment that will test how far your container needs to drop for the egg to break. 3 SAfeTy A Risk Assessment is required for this investigation. 2 Before you start constructing your container or start testing, assess your procedure. List any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required materials and start work. Results Construct a table to show the results of your egg drops and the heights they were dropped from. Practical review 1 State the height from which the egg eventually broke (if it ever broke). 2 Explain how you used air pressure to protect your egg. Properties of substances 61 ]]></TextData></Page><Page><Page_no>78</Page_no><display_no>62</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Liquid water freezes to form frost on cold mornings. When it’s really cold water can form ice and snow. As the temperature increases during the day, the frost, ice and snow begin to melt to form pools of liquid water. Water can be changed from one state into another by adding energy to it or by removing energy from it. This is done by heating it up or cooling it down. Changing state2.3 Melting Melting is the process in which heat causes a solid to change into a liquid. Although the physical properties of the substance change, the substance itself is exactly the same as it was before. Ice (solid water) is exactly the same substance as the liquid water it melts into when it is heated. Likewise, the solid wax that makes up a candle is exactly the same substance as the clear, molten drips of wax that slide down its side. Heat adds energy to the particles in a solid, making them vibrate faster. If you add enough heat, then the particles at the edges of the solid will be vibrating so violently that they will break free, allowing them to melt away from the others in the solid. You can see this in the melting butter in Figure 2.3.2. Figure 2.3.2 Melting starts at the edges of the solid because these particles $:$Dh0wJNBmvLpKs0mE4coVj6A5WzZHSdWzUtfEr7L2Ord7hVbEVmto1TUR2hXQqXnuGj7LfcbIX+Nt
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2S2cM+LWmX8zlqu/nqhDhWeVVh2Q8++Hwwu1aEJBlpA=$:$es its particles to move about more, and faster. If enough heat is added, particles break free from each other and the substance changes state: it may melt, evaporate or sublime. Figure 2.3.1 62 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>79</Page_no><display_no>63</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Melting point The temperature at which a solid melts is known as its melting point. A substance is solid below its melting point and is molten (a melted liquid) above it. For example, water, has a melting point of 0°C. Different substances have different melting points, as Table 2.3.1 shows. Table 2.3.1 The boiling, melting and freezing points of various substances Substance Boiling point (°C) Melting point (°C) Freezing point (°C) Ethanol (alcohol) 78 –114 –114 Water 100 0 0 Mercury 357 –39 –39 Silver 2193 961 961 Evaporation Evaporation is the process in which heat causes a liquid to change into a gas. Evaporation is sometimes also known as vaporisation. For example$:$rPyBywk3/RIcDDKiCSWnoZWi2Vb1OB49UCEuparZD68mIHCgVZAANrZdfkdcGnXHabzSnCnhji1A
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zNf2lw6paRm0BnoUW+cA+/VnzovilkHPtCR9K3dJP3FbfpvsSEQ=$:$the liquid formed is being heated • the liquid is starting to evaporate • the gas formed is being heated. Record this… Describe what happened. Explain why you think this happened. Condensation Condensation occurs when a substance loses heat and changes from a gas into a liquid. Your lungs are full of water vapour (gaseous water) that will condense into tiny droplets of liquid water when you breathe out onto something cold, like a window or mirror. Likewise, water vapour in the air will condense on a cold night to form droplets of liquid dew that will make the lawn and spider webs wet. This is shown in Figure 2.3.8. As a gas is cooled, its particles slow down. When they have slowed enough, the individual particles begin to attract each other and form bonds that will tie their movement to the other particles in the substance. They now act as a group, forming droplets of liquid. Steam is water vapour that has condensed to form a cloud of tiny but visible liquid water droplets in the air. Water vapour emerges as a gas from a kettle or from a boiling pot on the stove but quickly cools in the air to form a visible fog of tiny liquid water droplets. The dew on this spider web is caused by water vapour condensing overnight. Figure 2.3.8 Prac4 p. 70 2.4 2.5 Properties of substances 65 ]]></TextData></Page><Page><Page_no>82</Page_no><display_no>66</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review2.3 Remembering 1 State the temperature at which liquid water: a boils b freezes. 2 Name two substances that sublime. 3 State alternative words for: L a evaporation b freezing. 4 Recall the various changes of state by copying and completing Figure 2.3.9. Understanding 5 Explain why the melting point and freezing points of a substance are at exactly the same temperature. 6 Describe the signs that show that water is boiling. 7 You peg some wet clothes on a clothes line. Explain why the water in the clothes evaporates despite the temperature never getting near the boiling point of water. 8 Explain how: a snow forms b dew forms c frost forms. Applying 9 Identify two substances that: a melt at relatively low temperatures b evaporate at relatively low temperatures. 10 Identify the change of state that happens when: a ice-cream starts to drip b jelly sets c the bathroom mirror gets foggy. Figure 2.3.9 gas a c b d liquid solid 11 Use the information from Table 2.3.1 to predict what state ethanol, water, mercury and silver would be in at the following temperatures. a −20°C b 50°C c 200°C d 500°C 12 Sunglasses of$:$A0otHIs16UF4LWVmVPD4VY6BhKwQR1d2CoGAUR5ig70eYas5pe5+AtcCNi0GF3ptssC1SxfZOYSk
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v4zcdnLktjXSGvTLdTk0ANalEo1PVg==$:$t to water lowers its freezing point and increases its boiling point. Use this information to propose reasons why: a salt is spread on the roads in northern United States and Canada to help keep the roads clear of ice. b additives can stop a car radiator from boiling over. c ice-cream makers are cooled with a mixture of salt and ice. Inquiring 1 Search the internet to download 20 images of different-shaped snowflakes. Present your images as a slide show. ICT 2 Find out what supercooled water is and what it does when ice is added to it. Present your findings as a weblink or downloaded video. ICT N 66 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>83</Page_no><display_no>67</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigationsPractical investigations Rates of evaporation continued on next page Rates of evaporation Purpose To determine whether water or alcohol evaporates faster. Hypothesis Which do you think will evaporate faster—water or the alcohol that you find in substances like Deep Heat or Dencorub? Before you go any further with this investigation, write a hypothesis in your wor$:$dmm4RzHCL99DxXR/MWz1s7ZsMnFDYMUCxfx1BU9PaGViT03FN6m7amuFiNvkOaW3wheCpdySzdLF
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j/evt7tjKIuBA3EYXMXM3Y23E2A=$:$shown in Figure 2.3.10. 3 Lay the sheet of paper towel on your workbench. Note which streak ‘disappears’ first. Part B 4 Set up the apparatus as shown in Figure 2.3.11, taping the pencil so that it cannot move. 5 Pour 10 mL of water into one of the 100 mL beakers. 1 SAfeTy A Risk Assessment is required for this investigation. This kind of alcohol is extremely poisonous so do not sniff or taste it. It irritates eyes and open cuts so wear rubber gloves and safety glasses at all times. Alcohol is flammable so keep it away from all open flames. 6 Dip one strip marked Water into the beaker of water so that it soaks it up. Remove the strip from the water, making sure it does not rip. Drape the wet strip over one end of the ruler. 7 Pour 10 mL of alcohol into the other 100 mL beaker. 8 Roll the other strip of paper into a coil and place it in the beaker of alcohol. Once it has soaked up most of the alcohol, quickly remove it and drape it over the other end of the ruler. 9 Quickly balance the ruler and its strips on the pencil, noting which is the water end and which is the alcohol end. 10 Watch what happens to the ruler as the substances start to evaporate. Results Part A: Record which streak ‘disappeared’ first. Part B: Record which end of the ruler drops. Practical review 1 Compare your results from Parts A and B. 2 The water and alcohol don’t really ‘disappear’ in Part A. Describe what really happens to them. cotton bud paper towel water streak alcohol streak Figure 2.3.10 250 mL beaker paper strip soaked in water paper strip soaked in alcohol ruler pencil sticky-tape Figure 2.3.11 2.3 Properties of substances 67 ]]></TextData></Page><Page><Page_no>84</Page_no><display_no>68</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Rates of evaporation continued Temperature graphs continued on next page 3 The soaked paper strips in Part B become lighter as the experiment proceeds. Explain why. 4 The ruler becomes unbalanced if one of the substances evaporates faster than the other. Identify which end would drop if: a water evaporated faster than alcohol b alcohol evaporated faster than water. 5 a Use your answers to questions 1–4 to construct a conclusion for your investigation. Temperature graphs Purpose To determine what effect salt has on the melting and boiling points of water. Hypothesis What do you think will happen when salt is added to water – will it increase or decrease its melting and boiling points? Before you go any further with this investigation, write a hypothesis in your workbook. Materials • handful of crushed ice or ice cubes$:$R8JZfWKfKEpRRZNuOZ7231iQKqt5cWYec8tlh8kocvSXhLJhQtFpODgXH+e2UBsUQSIfOSniyK8S
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Q3hzRV5dsal+xUIuaI0ut5LdgPxM$:$ck the air out of a zip-lock bag and you will suck out the water vapour too. Results Construct labelled diagrams to show what happened. Practical review 1 Compare the beakers that you tested. 2 Explain any differences you saw. 3 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. 4 SAfeTy A Risk Assessment is required for this investigation. 70 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>87</Page_no><display_no>71</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Some materials like lead, gold, gr$:$pfr96ka+6Et26eLzcFqZsDsxsCy15reiiOK4XRpyDODKK/hC4MJ8Lk+cqgryfnyFbWiyq01EGPdo
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JdrKSAd5OyjQw5jaSNUVIV0=$:$ribe things such as: • its appearance • the temperatures at which it melts, freezes and boils • its hardness (how easy it is to scratch the material). Density is one of the physical properties of a substance. Density depends on how heavy a substance is, but it is not the same as its weight or mass. For example, 1 kilogram of lead always weighs exactly the same as 1 kilogram of polystyrene, which weighs as much as 1 kilogram of feathers. Density instead measures how much matter is packed into a specific space (Figure 2.4.1). Figure 2.4.1 Stones are much more dense than feathers. This makes a small pile of stones weigh a lot more than a big pile of feathers. science fun Salty lava lamp Can you make your own lava lamp? Collect this… • cooking oil • salt shaker • food dye • water • tall glass or 250mL beaker Do this… 1 Pour water into the glass or beaker until it is one-third full. 2 Add a few drops of food dye. 3 Pour in an equal quantity of cooking oil and observe which layer is on top. 4 Sprinkle salt into the glass and carefully observe what happens to the grains of salt. Record this… Describe what happened. Explain why you think this happened. Properties of substances 71 ]]></TextData></Page><Page><Page_no>88</Page_no><display_no>72</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[De$:$G6JzI1+JHwfhPUWgejOL6MOtzvAZ1IUFCdSHDIcBbqtHbOu1nQ7AqaNLqnQTQuw3KRJEEtkHRwqH
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FpEzJlJJXr/IJ+G9TqN0Zw==$:$sity even more. For this reason, hot air is less dense than cold air and will rise above it (Figure 2.4.3). This is why smoke rises—the air is hot and it carries soot and burnt material up with it. Likewise, bubbles of gas rise through the liquid, as seen in Figure 2.4.4. solid liquid gas Density depends on the packing of the particles making up a substance. The more closely packed, the denser the substance will be. Figure 2.4.2 Figure 2.4.3 The overall density of a hot-air balloon is less than the density of the air around it, allowing it to rise into the sky. Mass, volume and density Density depends on the amount of substance (its mass) and the space it takes up (its volume) and so its unit includes the units for mass and volume. Density is normally measured in gram per centimetre cubed (g/cm3 ). The densities of different gases, liquids and solids can be seen in Tables 2.4.1, 2.4.2 and 2.4.3. Gases are much less dense than liquids and will bubble upwards through them. Figure 2.4.4 Danny Deckchair Helium is a gas that is less dense than air. In 1982, US man Larry Walters tied 45 large helium-filled balloons to his aluminium garden chair and floated to a height of 4900 metres. After 45 minutes he punctured some of his balloons and crashed down among power lines. A similar flight was used in the plot of the 2003 Australian film Danny Deckchair. 72 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>89</Page_no><display_no>73</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Table 2.4.1 Densities of gases Gas Density (g/cm3 ) Hydrogen (at 0°C) 0.000 09 Helium (at 0°C) 0.000 18 Air (at 40°C) 0.001 1 Air (at 0°C) 0.001 3 Oxygen (at 0°C) 0.001 4 Table 2.4.2 Densities of liquids at 25°C Liquid Density (g/cm3 ) Petrol 0.80 Vegetable oil 0.91 Water 1.00 Honey 1.36 Mercury 13.6 Table 2.4.3 Densities of solids Solid Density (g/cm3 ) Polystyr$:$okTJA0rGfAHPGv+LmrsiZiQc5LBSJxIpDW6ZQzETBbgO+EEN9v6M+/PcSoAugajxanOly4T/0zRP
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sGi/PIMNLpchi5z9vP5/1zhh2shsKf6u41eTOgJL0sHm$:$s measured using a beam balance or electronic balance. A substance will be denser if more mass is packed into the same volume. The four cubes shown in Figure 2.4.5 are all exactly the same volume but their masses are all different. This means that their densities are different too. Unit 7.3 lead glassfoam rubber steel All of the cubes have exactly a volume of 1 cm3 . This makes the heaviest cube (lead) the densest and the lightest cube (foam rubber) the least dense. Figure 2.4.5 Density depends on volume Volume is the amount of space a substance takes up. Figure 2.4.6 shows that denser substances pack the same mass into smaller volumes. These substances all have the same mass of 10 grams. Denser substances require less volume to pack in the same mass. Here, the smallest volume represents the densest substance (brass). Figure 2.4.6 10 g balsa wood 10 g water (in glass jar) 10 g brass Properties of substances 73 ]]></TextData></Page><Page><Page_no>90</Page_no><display_no>74</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[100 90 80 70 60 20 30 40 50 10 100 90 80 70 60 20 30 40 50$:$3mi7ZwC2fM4+X1ALXZy1k3zP7p9Kldqfg7GvyT3C5lFkmMfI8uHZT7QS8CO1B0BsDtyv5RIuiDqc
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zd5h/B4YjpcdtyQmVo/3$:$ 0°C—it expands when heated and contracts when cooled. However, between 0°C and 4°C, water does the exact opposite. Water at 4°C is denser than at any other temperature, and drops to the bottom of any pond, lake or swimming pool. Colder water floats on top of it, and any ice will float on the surface of that colder water. This is shown in Figure 2.4.9. The water at the bottom of a pond, lake or swimming pool is always the densest. Even in freezing conditions, this layer is unlikely to drop below 4°C, giving fish some chance of survival. Figure 2.4.9 ice layer 1ºC 2ºC 3ºC 4ºC Calculating density Density measures the mass packed into a certain volume. This can be represented by the mathematical formula: density = mass volume Using symbols, this formula can be written as: d = m V Mass is normally measured in grams (g) and volume in cubic centimetres (cm3 ). 2.7 Problem Calculate the density of a pebble with a mass of 20 g and a volume of 10 cm3 . Solution density = mass volume = 20 10 = 2 g/cm3 Practice N Calculate the density of: a a piece of pine with a mass of 50 g and a volume of 100 cm3 b a sausage with a mass of 30 g and a volume of 30 mL. Calculating density WORKED EXAMPLE Pumice is less dense than water and so it floats. Obsidian is more dense than water and so it sinks. Density determines whether things float or sink. Figure 2.4.8 Prac1 p. 78 Properties of substances 75 ]]></TextData></Page><Page><Page_no>92</Page_no><display_no>76</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Icebergs Thicker, heavier chunks of ice will be partly submerged with only their top exposed, forming an iceberg. Despite their huge size and mass, icebergs float because their density is less than that of pure water and seawater, as shown in Table 2.4.5. Table 2.4.5 Densities of water Substance Density (g/cm3 ) Ice 0.92 Pure water 1.00 Seawater 1.03 Icebergs are incredibly dangerous to shipping because: • they shift with ocean currents and winds, often into shipping lanes. • 80–90% of the iceberg lies hidden below the water as shown in Figure 2.4.10. This hidden part doesn’t melt as fast as the ice above the water, and so it usually extends wider than the ice visible above the water line. Any ship that comes near can collide with this bulge, making a hole and sinking the ship. Most of an iceberg lies below the surface of the water. Figure 2.4.10 Although radar gives modern shipping some warning of a nearby iceberg, disaster can still happen. In 2007, the Canadian cruise ship MS Explorer (shown in Figure 2.4.11) hit submerged ice off Antarctica an$:$Xb6undGox5VllKn2wXPgsBMt1w/dxPsaW+6yra2gCjRqs2ocPIwZPB+An0CivW6E8r1mJh26viT5
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L+sOMMRKKDsM0JZnJX2zbg==$:$towed an iceberg into Sydney Harbour so that it could be broken up and sold off as ice cubes. However, rain soon exposed the ‘iceberg’ as a fake! It quickly washed off the shaving cream and firefighting foam and revealed white plastic beneath! It was April Fool’s Day! Prac2 p. 79 Prac3 p. 80 2.92.8 76 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>93</Page_no><display_no>77</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review Remembering 1 State whether each of the following is true or false. a 1 kg of lead has a greater mass than 1 kg of polystyrene. b 1 kg of lead takes up less space than 1 kg of polystyrene. c 1 kg of lead has the same density as 1 kg of polystyrene. 2 Recall the densities of different states and forms of water by arranging the following$:$hAUccUYmo+rowIUhDxc/s8Yt1dpabYe8DzJZ4A3L0B9Sv4J4rByDj+dYKd+OocEMbNi7UaWHJdFT
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CNUKt3rNh3nYrHBVgw==$:$balloons rise c spilt petrol forms a layer floating on top of water. 7 Figure 2.4.12 shows four diagrams of exactly the same substance. Identify which diagram best represents it: a as a solid b as a liquid c as a hot gas d as a cool gas e at its most dense f at its least dense. A B C D Figure 2.4.12 Analysing 8 Calculate the density of a solid that has a N volume of 2 cm3 and a mass of 3 g. 9 The pebble in Figure 2.4.7 had a mass of 60 g. Calculate its density. N 10 Calculate the missing numbers in the following unit conversions: N a 7 kg = __ g b 600 mL = __ cm3 c 4 t = __ g d 2 L = __ cm3 Evaluating CCT 11 a Predict whether you are more or less dense than water. b Justify your answer. 12 Newspaper usually floats on water but then sinks after a while. Propose reasons why. Creating CCT 13 a Construct a diagram showing a measuring cylinder containing all the liquids shown in Table 2.4.2 on page 73. b Small lumps of wood, copper and gold were then dropped into the measuring cylinder. Modify your diagram to show where each would settle. Inquiring 1 Find evacuation procedures recommended by your state fire service. Present your findings as a simple poster that displays an evacuation procedure. 2 The older ice in a glacier or an iceberg often has an incredible blue colour. Find images of a glacier or iceberg that has this blue colouring. Explain: • what causes the blue colour • how it is connected to density • why there are different shades of blue in the ice. Present your research in digital form. ICT 2.4 Properties of substances 77 ]]></TextData></Page><Page><Page_no>94</Page_no><display_no>78</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations2.4 Density tower Purpose To construct a tower of different liquids, layered according to their densities. Materials • 50 mL (maximum) each of corn syrup or honey, vegetable oil, ethanol or methylated spirits, coloured dishwashing liquid, water • a variety of small solids (such as a cornflake, single penne pasta, cork, sultana, bolt) • a few drops of food dye • rubber stopper, grape, Lego™ block • large measuring cylinder • small beaker • digital camera or mobile phone (optional) Procedure 1 Carefully squeeze the honey into the measuring cylinder so that it forms a layer at least 1 cm thick on the bottom. 2 Carefully squeeze or pour a similar quantity of dishwashing liquid into the measuring cylinder. Do this by tilting the cylinder and slowly pouring the dishwashing liquid down its side. 3 Choose a food dye that is a different colour from the dishwashing liquid. Add a few drops of it to a small beaker of water. Tilt the cylinder again, and carefully pour the coloured water in to form a 1 $:$ob5dInSWDG9t5o0papmsc5pAm2Vxx4kmwintsAdJO8cl1usCNxRml/RVhtVHcAyXQNVdLSgRGsKz
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jmBhF2RY5h6Dk21W2AgEqtEw/Gf0rC6ECw==$:$. Density measures how much of a substance fits into a volume. Which of the following shows the correct order of densities from highest to lowest density? A Highest density = concrete lead wood Lowest density = polystyrene B Highest density = lead concrete wood Lowest density = polystyrene C Highest density = concrete wood lead Lowest density = polystyrene D Highest density = lead polystyrene concrete Lowest density = wood CCT CCT lead concrete wood polystyrene Q3 Liquids do not always mix together. Sometimes one liquid floats on top of another. Alice filled a container with some liquids as shown. P, Q, R and S are different objects floating in the liquids. Z Y X W P Q R S What would happen if liquids X and Y were removed? Z W Z W Z W W Z P PPP Q Q Q Q R RRR S S SS A B C D Q4 Angus placed a plastic cup in a plastic container filled with water. He marked the level of the water on the cup and the container. water plastic container plastic cup mark on plastic cup mark on plastic container Angus then placed a heavy rock inside the plastic cup. What did he observe? CCT CCT A B C D 82 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>99</Page_no><display_no>83</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit 2.1 L Biodegradable: bacteria or fungi breaks down the substance into simpler substances Chemical properties: how substances react with other substances Compressed: squashed Incompressible: not able to be compressed or squashed Non-biodegradable: doesn’t rot or break down Odour: smell Physical properties: describe things about the substance like its appearance, melting, freezing and boiling points and its hardness Plasma: the fourth state of matter; found in sparks, lightning bolts and in stars States (phases): solid, liquid, gas (also plasma at temperatures above 6000˚C) Unit 2.2 L Bonds: forces of attraction that hold particles together (verb: bonds) Brownian motion: random motion of particles caused by being bumped and jostled by other particles Diffusion: a process in which two liquids or gases mix Gas laws: laws that describe how gas particles behave Indirect evidence: facts and evidence from which something e$:$iGL8G16yhVSmytVKzf5A2+YANbYdPIDyCl6POupz6+T8yES552BsZ+DgsF/SAIlkswC028Gh+7dR
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rgxI7XM2Y4v3kDuH8RCX4cgu$:$at water is an important resource that cycles through the environment • explain the physical processes involved in the water cycle • demonstrate how understanding the water cycle has influenced water management practices CCT S • research how Aboriginal and Torres Strait Islander peoples’ knowledge is used in management of resources AHC S IU • ADDITIONAL • describe ways technology has increased the variety of made resources L • debate the economic and environmental impacts of mining and resource exploration CCT PSC S • debate intergenerational aspects of using non-renewable resources. CCT PSC S After completing this chapter students should be able to: Have you ever wondered... • if humans could run out of resources like coal or oil? • why you should save energy? • how clouds form? • why people should care about what they put in the air or soil? ]]></TextData></Page><Page><Page_no>101</Page_no><display_no>85</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 85 Natural and made resources3.1 Humans need many things to stay alive, like food, air, water and shelter. Other living things have similar needs. These needs are met by the natural resources on Earth. It is the responsibility of everyone to protect these vital resources. science fun In the soil What is in soil? Collect this… • samples of different soils • stereomicroscope or hand lens • rubber gloves Do this… 1 Study one of the soil samples with a stereomicroscope at about ×40 magnification or with a hand lens. Is the material in the soil all the same or is it made of different materials? Try to work out what things are in this soil. 2 Study the other soils to see if they have the same materials in them. Record this… Describe what you saw. Explain why some samples were similar while others were different. SAfeTy Wear rubber gloves and mask. Natural resources A resource is anything obtained from the Earth to satisfy a particular need of humans or other living things. Most natural resources are substances, such as rocks, air or water. However, sunlight is a vital resource too. Sunlight is not a substance bu$:$3LH4LxI2LkyJlo7n2QQB/FAd8n0SL2BccdIRQr42Qn0dyODJHnlVlXytykLUgrae7Vk+ASO0qFtw
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4Q==$:$3.1.1 on page 86. ]]></TextData></Page><Page><Page_no>102</Page_no><display_no>86</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[86 PEARSON science NEW SOUTH WALES Animals, trees, soil, rocks, water, air and sunlight are natural resources. Figure 3.1.1 All life depends on these resources. Protecting them gives all living things (including us) a better chance of survival$:$xnGiyu2hKnWHUzeI4rOUfnIbqPoBH++SU6XbZRt8Vsx0u/5+CjrmgqnuBqkmvSWlMTQc6fwrmynS
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0aEjkFD9Pbtc2SGTAyGTrE/qFOdkLkn8drsKOvJffGknSdhMF+crCfM8vvgzVeiDzEFn7dZd$:$such as bricks and porcelain) made from clay • cements, made from limestone, clay and other minerals found in rock • medicines, made from plants, animals and minerals. Bread is a made resource. It’s produced from natural resources such as plant seeds like wheat, soy and rye. Figure 3.1.2 Renewable and non- renewable resources Some resources, such as sunlight, are renewable and will never run out. Other resources, such as minerals like iron, are non-renewable and can never be replaced once they are all used. A renewable resource is one that is replaced by natural processes at about the same rate at which it is being used. If the amount being used suddenly rises, then the ADDITIONAL Technology and made resources The variety of made resources increases as new technology is discovered. This means that new materials are continually being developed. For example, plastics were invented around 1900. Since that time, the use of plastics has become so widespread that they now replace wood, metal, cardboard and paper in many applications such as toys, computer cases, furniture, shopping bags, packaging trays, banknotes, and car and aircraft body parts. Carbon fibre was developed more recently as a strong but lighter replacement for metal. It is now used in F1 racing cars, tennis racquets, golf clubs, hockey sticks, bike frames and wheels, and the masts of yachts. Our ever-increasing understanding of genetics has led us to breed better plants and animals. In this way the amount and variety of food being grown is constantly increasing. ADDITIONAL ]]></TextData></Page><Page><Page_no>103</Page_no><display_no>87</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 87 resource may eventually run out. Careful management is required to ensure that this does not happen. An example is the timber in a forest. If the trees are cut down only as fast as new ones can grow then the forest will be renewable. In contrast, if all the trees are cut down at once, then the forest may never regrow. In this way, poor management of the resource can make it non- renewable. Figure 3.1.3 shows logging in the Amazon rainforest, the largest forest on Earth. Air, water, sunlight and living things are considered to be renewable resources. Non-renewable resources are those that take a very long time to be replaced, usually much longer than a human lifetime. Coal, oil and natural gas take many millions of years to form. Therefore, they are non-renewable and will eventually run out (Figure 3.1.4). Rocks, the minerals they contain, and soils are also non-renewable because they usually take thousands to millions of years to form. The Amazon rainforest in Brazil is a renewable resource only if the trees can regrow as fast as they are used$:$3r3R1c4W9TIethm1WywW5QbQbQFk8Qn3iv5OWxe3FSwd2FKeawNcZeOvtxysciWi67Z+DV4moGRg
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JK0HJQ==$:$hing, medicines, fertilisers, fuel and many other purposes. Living things also depend on their surroundings to supply other resources that they need. Water, rocks, air and soil supply the materials needed for all life. Sunlight is essential for plants to make their own food and to keep the Earth warm enough for life to exist. Living things: a renewable resource Living things are a renewable resource because they reproduce. A forest that has been cut down can regrow. Replacing some forests may take just a few decades, while other forests would take much longer to replace. Plantations (where trees are planted for timber) can be replaced faster than a natural forest. Animals, like the cows in Figure 3.1.6 on page 88, are replaced through reproduction. Replacing animals on farms may only take a year or so. This plant relies on the honeyeater to pollinate its flowers. To attract the honeyeater the plant produces a sugary substance called nectar. Figure 3.1.5 ]]></TextData></Page><Page><Page_no>104</Page_no><display_no>88</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[88 PEARSON science NEW SOUTH WALES Animals are a renewable resource because they reproduce. Figure 3.1.6 Air as a resource Air is a mixture of gases and suspended particles such as dust, smoke and water droplets. The main gases in air and their importance to life on Earth can be seen in Table 3.1.1. Table 3.1.1 Gases in the air Gas Percentage in air Importance to life Nitrogen 78% Provides nutrients for plants to make proteins and other chemicals, which humans and other animals can use as food. Oxygen 21% Essential for most living things, to release energy from food for their bodies to use. Carbon dioxide 0.03% Essential for plants to make their own food by photosynthesis. Other gases such as ozone, water vapour and argon 0.97% Many uses depending on the gas. • Ozone shields humans from ultraviolet rays (reducing our risk of skin cancers). • Water vapour is part of the water cycle that carries water around the planet. • Argon is $:$7hshMjCExB8I1ML1Nq8uFbTRJz+/egqTlP9ZVHvek7EVSGAUC37pLfjwKOiIWLy5D4b9t2ucSTPK
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43u4tuZMV5/qBNql2hrn$:$describe the movement of materials from one place to another and back again as a ‘cycle’. Oxygen cycles through the Earth’s atmosphere, soils, rocks, water and organisms. Green plants use carbon dioxide, water and energy from sunlight to make their food (sugar) by the process of photosynthesis. Figure 3.1.7 Earth’s fragile atmosphere The atmosphere is the very thin layer of air around the Earth’s surface. The first astronauts who ventured into space were amazed at how thin and fragile the atmosphere looked from space. Many said it made them think very deeply about the damage humans are doing to the atmosphere. ]]></TextData></Page><Page><Page_no>105</Page_no><display_no>89</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 89 Only about 0.03% of air is carbon dioxide. This is enough to supply the carbon dioxide needed by plants to carry out photosynthesis. Animals breathe out carbon dioxide because it is a waste product of the processes that release energy in their bodies. So carbon dioxide is also being replaced in the air. It is part of a cycle, in which it goes from the atmosphere to plants, and then back again from animals to the air. This cycle of oxygen and carbon dioxide is shown in Figure 3.1.8. The most abundant gas in air is nitrogen (78%). Nitrogen gas also has its own cycle as it is absorbed by some organisms and released by others. Sunlight as a resource Sunlight is essential for life on Earth. This is because: • plant$:$kuSrWFGkVGRMzw/AjUz3wZDt8W8kISGQlSJwkmAdS1pr9a6aMeox5vCh6g5x0uvf/5G3AcOKqM7o
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O0qPSHu2dA5ICifI+jwVSGAUC37pLfjwKOiIWLy5121W7mpyCBIT4rd4MRRHb+fPzxhnCBLd$:$e resource and will be for as long as the Sun keeps shining. The Sun is a star, and it will continue to shine for billions of years. Water as a resource Water covers most of Earth’s surface and all living things (like the bird in Figure 3.1.9) need it. No organism can live without water for long. For this reason, water is Earth’s most important resource. Water: a renewable resource Water is a renewable resource because it can move from place to place and replenish an area. It has a cycle. Only a tiny fraction of the water on Earth is made new each day. Some water is made whenever: • living things like trees burn • fossil fuels like petrol and coal burn • living things release energy in their bodies. The total amount of water on Earth is thought not to have changed much since the planet formed. Unit 3.3 Unit 3.4 Living on other planets Life cannot exist without water. For this reason, scientists searching for signs of life in space are only looking at planets and moons where water can be detected. Water is the most important resource on Earth because no living thing can survive without it. Figure 3.1.9 ]]></TextData></Page><Page><Page_no>106</Page_no><display_no>90</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[90 PEARSON science NEW SOUTH WALES Rocks as a resource Rocks provide two different resources: • the rocks themselves • minerals found in rocks. There are many different types of rock. Some types are hard and can be used without altering them or removing any materials from them. These rocks are used mainly for roads and buildings, like the one shown in Figure 3.1.10. Other types of rocks are soft, like limestone and sandstone. These rocks are easy to cut, so they are used in paving and walls. Many of the early buildings of Sydney are built from local sandstone. Rocks are made from substances called minerals. Minerals differ in their physical properties such as colour and hardness. You can see how minerals appear in a magnified view of a rock in Figure 3.1.11. Many minerals are important resources for humans. A variety of minerals and their uses are shown in Table 3.1.2. Stone buildings are built from rocks. Figure 3.1.10 Figure 3.1.11 This is a magnified view of a rock showing that it is composed of different minerals. Each different colour is a different mineral. Table 3.1.2 Minerals and their uses Mineral Main use Bauxite Contains aluminium. Aluminium is used for making aircraft, drink cans and high voltage powerlines. Haematite Contains iron. Iron is used to make steel, which is used in car bodies, nails, ships and bridges. Malachite Contains copper. Copper is used in electrical wiring. Halite Contains sodium chloride (table salt). Sodium chloride is used in food preparation and medical applications. Rocks contain some of the minerals that are needed by living things. As the rocks gradually break down, they release minerals which end up in the $:$BV7h7HPElmGrvil8iCnoOlhia5OeQ7KMIWClVmwB0H3e/1m9LXs8Qx4ZM5krfOIj0yU/UuKeaBrS
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qwXUJ7GodUc3dfGS$:$cks form. The igneous rocks that form when magma cools below ground can take thousands to millions of years to form. In contrast, igneous rocks form on the surface in a day or so (Figure 3.1.12). This is because the liquid rock (lava) cools quickly in the air or under the sea. Although new rocks form every day, they cannot be considered renewable because the overall process takes so long. Figure 3.1.12 ]]></TextData></Page><Page><Page_no>107</Page_no><display_no>91</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 91 Other types of rocks form when sediments (sand, silt and clay) stick together and harden to become rock. This type of rock is called sedimentary rock. Most sedimentary rocks form over many thousands or millions of years. Only a tiny fraction of Earth’s rocks is being replaced each year. The replacement takes so long that rocks cannot be considered to be renewable resources. Therefore the minerals in the rocks are considered to be non-renewable resources too. Fossil fuels, like oil and coal, were formed from dead plants and animals that lived many millions of years ago and are not being formed today. For this reason, fossil fuels are also non-renewable resources. Pearson science NSW 8 Chapter 8 Soil as a resource Rocks are broken down (weathered) into smaller particles such as sand, silt and clay. The small particles are carried away by wind, water and ice in a process called erosion. The particles are then dropped somewhere when the wind, water or ice stops carrying them. When the particles drop, this is called deposition. You can see sand being deposited in Figure 3.1.13. This sandstorm approaching the Saudi Arabian capital Riyadh shows how much erosion and deposition the wind can cause. Figure 3.1.13 The deposited sediments are added to any soil they fall on, making new soil in the process. Soils are composed of: • fine rock particles (sediments) • living organisms (such as worms and moss) • humus (decaying wastes and dead organisms) • water • dissolved minerals and gases. Soil: a non-renewable resource In some places the rock particles carried by water, wind and ice can build up quickly. An example is where many rivers carrying sediments meet in a river flood plain. In this way the soil is continually added to. Soil can also be enriched in home gardens or $:$ym1oFqqTu+Y7PvSnqPmRJxJFXLzBoV+m3UCBwnWSrIxRnGY2h6sx/sRJfvFem/sdW8XOpoTpPvh1
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EWgIw20wYoeqLHz/Kg==$:$rip topsoil from the ground and make it very difficult for any crops to grow. Figure 3.1.14 ]]></TextData></Page><Page><Page_no>108</Page_no><display_no>92</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[92 PEARSON science NEW SOUTH WALES Conserving resources There are several ways we all can save our valuable resources. • Limiting consumption: Everyone should avoid wasting resources by only using as much of the resources as is needed. For example, you can save energy by turning off lights that are not needed in rooms. • Increasing the price: One strategy used by governments to encourage people to limit resource use is to charge a lot for resources such as water, gas and electricity. This works because people will not waste a resource if it costs them a lot of money. • Using alternative resources: Another strategy to limit the use of a resource is to develop alternatives to it. For example, cars with electric engi$:$uaaCkAi3MU0GUNlwhG/29kKajs7KHBvmrcf9rKQcsDpzuWLsdpIu+TyMDg5nqYy7ROm8FnUPZuEN
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$:$campaigns use the media to educate people about the need to conserve resources. These campaigns encourage people to limit their consumption because it saves them money and is better for the community. • Recycling: Recycling is the process of re-using materials rather than throwing them away then having to make more of the material. For example, re-using aluminium means that less bauxite (aluminium ore) needs to be mined. Recycling materials such as iron, glass, copper, paper, wood and clay bricks also saves resources. Using the recycling bins that your council provides is an important way of recycling materials. ]]></TextData></Page><Page><Page_no>109</Page_no><display_no>93</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 93 the CurriCulum learning aCross Difference anD Diversity The economic benefit gained from mining a particular resource is affected by the changing prices obtained for the resource and the ‘life’ of the mine. Mines only continue while they are profitable or until the resource runs out. New technology can make some old mines profitable to use again. Sometimes new technology allows an entirely new type of mining. An example of this is fracking, in which water and other chemicals are pumped into rocks, causing them to fracture (break). The cracks allow resources to escape from the rock so that they can be extracted. In Australia, fracking is used to release natural gas from coal. This gas is known as coal seam gas. However, there have been cases in the USA where fracking has contaminated water supplies. In rural NSW, groups have protested against the use of fracking. One such protest is shown in Figure 3.1.16. Cost and efficiency are major considerations with any new technology. The new method will be favoured if it is more efficient in supplying the resource or if it is cheaper than the old method. The new technology will also be favoured if it causes less damage to the environment. The most difficult decision is whether to allow some environmental damage because the technology is cheaper. One major issue at present in Australia is the burning of coal to generate power. Coal burning produces carbon dioxide gas, which most scientists b$:$TEH7mRGgKuvVSCmrK/xWH6ZkyT43lztw4uNR1RJQui/Kcl2JacsGZt6bg0hsQl03YbT6Cu2pIY9U
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k07QSWystIVoowxmgXNxexe8Coo1o1HkN2swNJ+bUF81W1Em9ALo6IPMQWft1l0=$:$important. This is especially so when considering the use of new technology to obtain a resource. A protest in NSW against using fracking to extract coal seam gas. Figure 3.1.16 ]]></TextData></Page><Page><Page_no>110</Page_no><display_no>94</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[94 PEARSON science NEW SOUTH WALES Aboriginal rock art at Nourlangie Rock in Kakadu National Park, Northern Territory. The area is so important that it is protected as a World Heritage Site. Figure 3.1.17 indigenous australians and resourCes The knowledge of Indigenous Australians has been useful in protecting the environment in resource developments. Their knowledge of plants and animals, rock art and fossil sites (Figure 3.1.17) has been used by state and federal governments when making deci$:$Ulk4A6iBZecGSBSng0DHdb2GbpNqSy51Be/TIlkP2WM/oxPv7QBU4CUOmn8S14tDt5evRXbAsSXj
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Mv/UwgfrA+uG2wtEe+MD0BrI18t22k4JolxA1w4vS6fq$:$ people. • Native Title laws enable Indigenous people to make a claim to traditional land where they and their ancestors have lived. review 1 State the two major factors that affect resource development. 2 Describe the process of fracking. 3 Propose why farmers and miners in rural NSW may have different, opposing views on using fracking to mine coal seam gas. 4 Propose why it is a difficult decision to use new technology that may be much cheaper but could cause damage to the environment. 5 Assess whether economics (money) should be as important as environmental damage when considering the long-term survival of life on Earth. 6 Clarify why the knowledge of Indigenous Australians is useful in determining the environmental impact of a mine. ]]></TextData></Page><Page><Page_no>111</Page_no><display_no>95</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 95 Unit review3.1 Remembering 1 List the major natural resources of the Earth. 2 List ten made resources that help humans survive. 3 List five strategies that assist in conserving resources. 4 Recall two factors that must be considered when deciding whether to develop resources. Understanding 5 Define the term resource. L 6 Explain why it is important to conserve no$:$lR3sXnSuYhuCwDlaGZuaEC96OfPr+lSeRqL0cKMdRaB93j0uN32pbR0So+xdP/UyZ/P1WxQzVZUI
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gChHQwO4$:$what happens. 1 oxygen Flask A plant, water, carbon dioxide and light Flask B plant, water and light, no carbon dioxide Flask C plant, water and carbon dioxide, no light sunlight Figure 3.1.18 Results Record your results in a table like the one below. What happened to splint Test-tube A Test-tube B Test-tube C Practical review 1 Describe the results for each test-tube. 2 Oxygen gas has the ability to make a glowing splint of wood catch fire again. Deduce whether any of the test-tubes contained oxygen. 3 Propose what happened in the three conical flasks. 4 Explain how this experiment is relevant to the importance of air as a resource. 5 Explain how this prac shows that sunlight is a resource. ]]></TextData></Page><Page><Page_no>113</Page_no><display_no>97</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 97 Water-holding capacity of soil Purpose To compare the water-holding capacity of different soils. Hypothesis Which soil type do you think will be able to hold more water—sand, loam or clay? Before you go any further with this investigation, write a hypothesis in your workbook. Materials • 100 mL each of dry clay, loam and sand • 3 plastic filter funnels • retort stand and 3 clamps, or filter stands • 3 × 100 mL beakers • 50 mL measuring cylinder • cotton wool • rubber gloves Procedure 1 Set up the equipment as shown in Figure 3.1.19, with a cotton wool plug in the neck of each funnel. 2 SAfeTy Do not inhale or touch the soil with bare hands—it can contain dangerous organisms (pathogens$:$6MH7kbwmjag3Y4IQdzd8DZcuqlApjHgBu4TktBFhmF4x7gZ5UbHj2QF/XTrSihZRzfAVMvabfEK2
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JkbJPxmqN6MTb6sqHAeBzw==$:$rd in a table how much water you added to each soil and how much water collected in the beaker. Practical review 1 a Identify the soil which has the largest water- holding capacity and the soil that has the smallest capacity. b Justify your decision. 2 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. 3 Outline some possible reasons why the soils had different water-holding capacities. 4 Soils described as ‘well drained’ allow much of the water that enters them to pass through them. Labels on plants at a plant nursery sometimes say that the plant likes well-drained soils. Propose the characteristics of soils that make them well drained. ]]></TextData></Page><Page><Page_no>114</Page_no><display_no>98</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[98 PEARSON science NEW SOUTH WALES Practical investigations STUDeNT DeSIGN 3.1 Erosion on a slope Purpose To test if the amount of soil erosion depends on the slope of the land over which the water runs. Hypothesis Which slope do you think will have the greatest erosion—a shallow or a steep slope? Before you go any further with this investigation, write a hypothesis in your workbook. Materials • 20 L dry sand • 20 L dry loam • plastic gutter • bucket • tap • hand lens or microscope • protractor • wooden blocks or bricks • rubber gloves Procedure 1 Design an investigation that will test how the angle of a slope affects the amount of soil erosion when water runs down it. Figure 3.1.20 shows water cascading down a hill. 2 In your design you can use any$:$HDfoeryjmlupfDdCzzhowwmqPghClomc4BDRCtIj5v7+Txf1G35/biIh7mtcZEFPcvi3aFD5mK/M
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kmI4jX0iae8=$:$nt of its risks. If they approve, then collect all the required materials and start work. 3 SAfeTy Do not inhale or touch the soil with bare hands—it can contain dangerous organisms (pathogens) and can also trigger asthma. Wear rubber gloves at all times and wash your hands afterwards. Results Record your results and observations. Practical review 1 Evaluate your procedure. 2 Outline how your procedure could have been improved. 3 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. Does the slope of the land affect the amount of soil erosion caused by water? Figure 3.1.20 ]]></TextData></Page><Page><Page_no>115</Page_no><display_no>99</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 99 In Australia, the burning of coal generates most of our electricity. Fossil fuels produce vast amounts of the greenhouse gas carbon dioxide. This gives Australia one of the highest rates of greenhouse gas $:$ht5a5DZsFsVar1NHdivmB5RZyM98WXH+h9pHuYhgEAcjh4n9n4hLaU9GprKPqrDCPOqzwM+KdAoh
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C73pz6pppQY=$:$Australia 235 Canada 310 China 76 Egypt 38 El Salvador 28 Ethiopia 17 Greece 103 Italy 119 Pakistan 20 United Kingdom 137 United States 301 3.3 Non-renewable energy sources Oil, coal, gas and nuclear are energy sources that cannot be replaced. Energy sources such as these are called non-renewable energy sources. Oil, coal, gas and their products (such as petrol and diesel) are known as fossil fuels. Some 300 million years ago, the dead remains of prehistoric animals and plants were covered by layers of mud, sand and dirt. Pressure and heat below the Earth’s surface gradually transformed these remains into the different fossil fuels found today. The original source of energy for these fuels was the sunlight absorbed by the prehistoric plants. It was stored in their remains or in the remains of the animals that ate the plants. When burnt, fossil fuels release large amounts of energy but also large amounts of the greenhouse gas carbon dioxide. This increased concentration of carbon dioxide in the atmosphere is thought to contribute to climate change. Nuclear fuels, such as uranium and plutonium, are non- renewable sources of energy that are used as the main power source in many countries overseas. There are no nuclear power plants in Australia. The nuclear reactor at Lucas Heights in Sydney only produces radioisotopes for use in medicine and engineering. Small amounts of these fuels can produce large amounts of energy in a chain reaction in a process called nuclear fission. This chain reaction is carefully controlled in a nuclear power plant. The heat created is used to generate electricity. Nuclear power plants do not produce greenhouse gas emissions. However, the process of nuclear fission used produces wastes that remain radioactive for thousands of years. Long-term safe storage of these wastes remains a problem. Figure 3.2.2 shows that more than 80% of the world’s energy supply is obtained from oil, coal and gas. These are all non-renewable fossil fuels. Australia has plentiful supplies of coal and it is relatively cheap. Major energy sources used in Australia include: • black and brown coal, to produce steam used to generate most of our electricity • petrol to power most of our cars, with some using LPG (liquefied petroleum gas, another fossil fuel) • diesel to power most trucks, cars and tractors and some trains • natural gas for much of our cooking, central heating and hot water services. ]]></TextData></Page><Page><Page_no>117</Page_no><display_no>101</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 101 Renewable energy sources Renewable energy sources can be used over and over again. If we want to build an energy supply for the future and to limit greenhouse gas emissions then we need to switch from fossil fuels to renewable sources. Power companies offer households the option to buy all or some of their electricity from a green power provider. Oil 37% Coal 25% Gas 23% Nuclear 6% Solar heat 0.5% Wind 0.3% Geothermal 0.2% Biofuels 0.2% Solar photovoltaic 0.04% Biomass 6% Hydro 6% This chart shows where the world’s energy comes from. The second and third rows show detail that cannot be seen in the smallest bands of the row above. Figure 3.2.2 You pay slightly more but you buy electricity that has been sourced from renewable energy. Key sources of renewable energy are: • moving water • heat within the Earth • Sun • oceans and rivers • wind • biomass. Figure 3.2.3 highlights the regions of the world best suited to each type of renewable energy. Average wave flux (kW per metre of wavefront) Geothermal power Depth (metres) to reach 170$:$czaWcu4YipJ/5+B7zezPhkFyq7AU/nJkjZHcG4F34/6uliwJirqTHtc7QpVhyUDn7DQ3bnwjA93E
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tq3xBFn8ujw=$:$ellow shading indicates the average solar radiation reaching the surface of the Earth. The purple zones indicate regions of high wind speed. The blue lines indicate high tidal activity. The dotted zones indicate where heat is relatively close under the Earth’s crust. Figure 3.2.3 ]]></TextData></Page><Page><Page_no>118</Page_no><display_no>102</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[102 PEARSON science NEW SOUTH WALES A major problem with renewable energy sources is that their energy output is not continuous. Wind turbines, solar systems and wave generators rely upon the wind blowing, sun shining and waves breaking. Better methods need to be developed to store renewable energy when demand is low so that it can be used later when demand rises. Hydroelectricity Gravity causes things to fall, including water. Water falling from a higher to a lower level (such as from the dam shown in Figure 3.2.4) can be used to turn turbines and generate electricity. This form of electricity is called hydroelectricity. The Snowy Mountains hydroelectric scheme in NSW is the largest hydroelectric power scheme in Australia. It consists of 16 dams, 7 power stations and over 145 km of tunnels. Hydroelectric schemes are a renewable energy resource. However, large-scale projects change the way rivers flow and alter the environment. The energy of falling water is used to turn turbines that generate electricity in a hydroelectric power station. Figure 3.2.4 Biomass Biomass is material, such as dead plants, other types of plant matter, or animals and their wastes, from which energy can be obtained. These materials contain stored energy captured from the Sun. This energy can be released for use in many different ways: • Heat energy is released wh$:$AI4Xh1F090IrPupUAMbzbcV9eYZ7mAKabwBBLXwvaIISjaG1DHUaZUUfu+T4dqUfHC13/mBfSCiB
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PlI9yp19Sg+/NnOcChI1GcdF/TpB$:$el fuel can be made from vegetable oils extracted from plant seeds, such as palm oil, sunflower, canola, soybean, sesame and linseed, or by harvesting algae. Prac1 p. 110 3.4 Corn ethanol is produced in this processing plant in Iowa, USA. The corn grain shown here is a waste product of the process and is sold as animal feed. Figure 3.2.5 A sugar rush Brazil produces vast crops of sugarcane and uses some to produce ethanol. Most new cars are designed to run on ethanol. This change has lessened Brazil’s dependence on oil – its cars are essentially solar powered! ]]></TextData></Page><Page><Page_no>119</Page_no><display_no>103</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 103 Solar energy Light from the Sun is a valuable renewable resource. It can be used in many ways to provide energy. $:$69sKw40aF+rPTb6rg7T9sNn0pwX3zFgzWRSBODqhO1Y9HRCrJG137s6uwodxYfIc6u8VV5jrUq1r
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DmfNyFipEbAvSjvmqZDnvYtxtLPTJqFSOs2RJfTX$:$n be fed back into the electricity grid or into storage batteries. Solar cells are expensive to produce, but the amount of electricity they make is increasing each year. This increased efficiency of solar cells is making them more affordable to householders. • A solar pond consists of a large volume of water to which salt is added. The pond is lined with black plastic. Sunlight heats water at the base of the pond, and the heat can be used to generate electricity. • Large-scale solar energy systems, such as that shown in Figure 3.2.7, rely upon vast arrays of mirrors to concentrate sunlight. These devices can be used to generate electricity with no greenhouse gas emissions. Wind energy Wind energy has been used for centuries and windmills have long been used in Australia to pump water. Wind turbines are like large windmills but are used to generate electricity. Wind farms are located in windy places. You can see a wind farm in Figure 3.2.8. Prac2 p. 111 Wind energy generates no greenhouse gas emissions. Nearby residents may object to wind farms because they produce some noise and birds may be injured by the turbines as they spin. Figure 3.2.8 20 m Sun’s rays parabolic reflector concentrates Sun’s energy 63 mirrors (heliostats) track the Sun and direct the Sun’s rays into the parabolic reflector 42m A solar furnace can produce temperatures up to 3800°C. Solar furnaces, such as this one in Odeillo, France, can be used to generate electricity. Figure 3.2.7 Solar cells are useful for providing energy to small-scale devices, such as calculators or garden lighting, and for providing electricity in remote areas. Figure 3.2.6 ]]></TextData></Page><Page><Page_no>120</Page_no><display_no>104</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[104 PEARSON science NEW SOUTH WALES Energy from the ocean There are a number of different techniques that harness energy from the ocean. Although these techniques are generally expensive to establish, they offer a clean energy source once they are operating. An oscillating wave column (shown in Figure 3.2.9) and a tidal barrage (shown in Figure 3.2.10) are two examples. The oscillating wave column relies on the pressure of the waves to suck air in and out around a turbine to generate electricity. Figure 3.2.9 turbine Incoming wave forces air out Retreating wave sucks air back in Turbine turns in same direction irrespective of direction of airflow Geothermal energy Beneath the Earth’s crust lies molten magma (melted rock). In Iceland, Japan and New Zealand, this heat lies fairly close to the surface and heated water may burst from the surface as a natural hot spring or geyser like the one shown in Figure 3.2.11. This heated water can be used directly to generate electricity. Another way to use geothermal energy is to pump water underground through drilled channels and circulate it through the hot rock. The water is heated by the rock and is used to generate electricity whe$:$kNnGLzD5kvycVzlHNiiUAtO5KOOMmTrdZt+Rvo/lA8/k3aDC/UTWIye1d7huZN5kWw1sA+5cimoK
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LWhY9Qx13ctzbeEgrXmB1Lp9K6Id1Lald0579a34FA==$:$ tide rises, water moves into the basin, turning a turbine. At high tide, the gates are shut. At low tide, the gates of the tidal barrage open to allow water to fill a basin. These gates are shut at high tide. When the tide is low, the gates are reopened and the pressure of water rushing out is used to generate electricity. Figure 3.2.10 This steam is produced by geothermally heated water in Iceland. Figure 3.2.11 ]]></TextData></Page><Page><Page_no>121</Page_no><display_no>105</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 105 generator building hot rocks water heats up hot water up cold water down pump house A geothermal power plant pumps cold water below the surface where it is naturally heated over hot rocks. It then returns to the surface. Figure 3.2.12 Powering NSW Fossil fuels supply 94% of the energy needed in NSW. Coal and petroleum (petrol) make up most of the fossil fuels used. As Figure 3.2.13 shows, electricity supplied by renewable sources is a small part of the total energy used in the state. Electricity generated from renewable sources is on the rise. From 2001–08, electricity from renewable sources contributed 6% of the total electricity produced but by 2010 this type of energy supply had doubled. In NSW, the main renewables used are hydroelectricity, biomass (wood, wood waste, biogas, biofuels) a$:$itG+Xb2nlPGfJ5F9t/MgdKYy2d3rmDixFbnOWFbX5pEZZFzytunfSFYOPhjDdvAZJQHNqDjJUCxw
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jBaW9R08JQc5DqTHhMjmtpFO34fKGkEeelPWi8j0ke8j8KBeZKlW7yHQv80M1sM=$:$an 13000 people. Figure 3.2.14 shows the location of the coalfields of the Gunnedah basin. Walgett Moree Narrabri Coonamble Gilgandra Gunnedah GUNNEDAH BASIN Coonabarabran Quirindi Muswellbrook Dunedoo Wee Waa BathurstOrange Maitland Tamworth Dubbo Gosford Newcastle Sydney Collarenebri Glen Innes Armidale Coolah Namoi R 200 km0 100 The Gunnedah basin contains almost all of the coal resources found in NSW. This area of land is approximately 500 km long by 150 km wide. Figure 3.2.14 Powerful Gunnedah In the 1800s, trains, steamships and most machinery were driven by steam engines, which burned coal. Back then, coal was as important as oil is to us today. The rich coal seam beneath the Gunnedah region was discovered in 1877 by a local farmer boring for water. Prior to that, the area derived its wealth from sheep and wheat farming. ]]></TextData></Page><Page><Page_no>122</Page_no><display_no>106</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[106 PEARSON science NEW SOUTH WALES The coal mining industry provides a reliable source of energy, income and employment, but there are serious concerns about its impact on the environment. These include: • the emission (release) of large quantities of greenhouse gases (particularly carbon dioxide) produced when coal is burnt • pollution of surface and groundwater • erosion and changes to the landform (Figure 3.2.15) • changes to the environment that might make it more difficult for different types of animals and plants to survive. Carbon capture and storage is the process whereby carbon dioxide gas is isolated and captured either before or after coal is burnt. Once captured, the carbon dioxide is liquefied (changed into a liquid). It is then pumped into geological formations where it is to be stored underground. This is shown in Figure 3.2.16. Such ‘clean coal technologies’ aim to $:$5kJxPFiItt3iTzlZScMANrlpHh4lhgcvE/xhTHbBRtKna2HOhuE4m6uufgd81M8IPzqV9FHf+0v/
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vMZxptkO6H/S6qXSMJpnf7VJVLbD1hoqoyEzMqFVSCDR/AIrozduhLisjMsT$:$ergy hubs in Africa and 20 in Asia. For a small fee, locals can use this electricity to recharge energy-efficient fluorescent lamps for use on their boats and in their homes. They can also take a rechargeable battery from the energy hub to power fishing lamps. Typical lamps are shown in Figures 3.2.17 and 3.2.18. They rely on an 11W globe and are watertight and dust resistant. Costs are much lower than the equivalent costs for kerosene, the light from the lamps is brighter, it carries no health risks, and no greenhouse gases are produced in the process. The battery can also be used to operate or charge small appliances such as mobile phones and radios. When the batteries are flat, they are brought back to the hub for recharging and are swapped for a charged battery. The woman shown in Figure 3.2.17 is carrying a lantern with an internal rechargeable battery. This lantern operates for 8 hours, or even longer when switched to a lower power LED light designed to provide enough light to read a book at night. review 1 State the fraction of the world’s population that has no access to electricity. 2 List the disadvantages of using kerosene as a light source in remote communities. 3 Outline how the program Umeme Kwa Wote provides solar lights in Kenya. 4 Propose areas in Australia that might benefit from a similar scheme. umeme Kwa wote— energy for all About one-quarter of the world’s population does not have access to an electricity supply. This Kenyan woman carries a chargeable solar-powered lamp. Figure 3.2.17 These fishermen on Lake Victoria plan to catch sardines attracted by the light source. Figure 3.2.18 ]]></TextData></Page><Page><Page_no>124</Page_no><display_no>108</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[108 PEARSON science NEW SOUTH WALES Unit review3.2 Remembering 1 Refer to Figure 3.2.1 on page 100 and state the approximate energy use (in petajoules) in NSW in the years: a 1990 b 1999–2000 c 2010. 2 a State one key advantage of fossil fuels. b State two key disadvantages fossil fuel. 3 State one advantage and one disadvantage associated with the use of nuclear fuel. 4 List the three sources of energy that supply the majority of the world’s needs. 5 List five types of plant seeds that can be used $:$2KNy2cuAmFakRAKKrMgVd+TT4iaHqRaK4CEsCAgYlv/qWioQiP4sqwUssRY12uxhhbW7l0bpJo5D
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k7PTz0ggz9ItAXXRDSEn3MC4V90=$:$e energy use in gigajoules (GJ) of an Australian over a year. b Calculate this value in joules (J). N N 16 Each situation a–h below describes different energy changes. Use the options below to identify which type of energy is being used in each case. hydroelectricity oscillating wave column biomass fossil fuel tidal barrage solar energy geothermal energy wind energy a Wood is burnt in a camp oven to boil a kettle. b Natural gas is used to heat a saucepan of pasta on a stove. c Falling water turns turbines that generate electricity. d Sunlight falling on a photovoltaic cell is directly converted into electricity. e Turbines rotate as air flows through them and this is used to generate electricity. f A turbine rotates in one direction and then the other as moving water sucks air past its blades. g Water flows rapidly over a turbine, which is used to generate electricity. h Water pumped below the surface of the Earth is heated and used to generate electricity. 17 Use Figure 3.2.2 on page 101 to state the percentage of world energy consumption supplied by: a oil b solar photovoltaic energy c nuclear energy. 18 Use Figure 3.2.13 on page 105 to list the energy sources used to provide electricity for NSW in order from the largest to the smallest contributor. Analysing 19 a Identify the source of energy being used in the science4fun activity on page 99. b Classify this as a non-renewable or a renewable energy source. 20 Compare the key advantages and disadvantages of two renewable energy sources, such as solar, wind, tidal, geothermal or hydroelectric energy production. N N ]]></TextData></Page><Page><Page_no>125</Page_no><display_no>109</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 109 Evaluating CCT 21 a Assess whether nuclear energy is a renewable or non-renewable energy source. b Justify your answer. 22 Refer to Figure 3.2.3 on page 101 to answer the following questions. a State the current production of electricity from solar sources (in terawatt hours per year, TWh/yr). b State how much electricity could potentially be produced from solar sources (in TWh/yr). c Propose three regions of the world that would be best suited to utilising: i solar energy ii wind energy iii ocean energy iv geothermal energy. d Looking at Australia on this illustration, propose which renewable resource you think would be best suited to development in NSW. 23 Propose what is meant by the term green energy. L 24 Propose reasons why electricity demand in NSW drops occasionally during a day or over a year. Creating CCT 25 Australia has plenty of brown and black coal. It is relatively easily mined and relatively cheap. a Construct an argument for or against the use of coal as an energy resource. b Use the arguments of the class to run a debate on whether coal should continue to be used as a major source of electrical energy in Australia. Inquiring 1 Many remote communities in Australia are located large distances from the electricity grid. These communities generally rely on isolated diesel power stations. Such diesel power stations are affected by price variations in diesel fuel and also contribute greenhouse gases to the atmosphere. • Research other sources o$:$2A57tbSELF479OVxfs32s8n8MqD1od+wBLn+e4KAGH3B+dZT2XoohPwy6Gtp4O3wOn90Jhk8aj1d
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UUNJklvHhrUo3muz16EAL4QBTDgjpXdOe/Wt+BQ=$:$rgenerational means. • Explain what is meant by the term non- renewable resource. • Outline what you think is meant by the term intergenerational justice when linked with non- renewable resources. • Construct arguments that agree or disagree with the statement that: People today must have a sense of intergenerational justice when using non-renewable resources. Present your findings as a Word document. ICT ADDITIONAL ]]></TextData></Page><Page><Page_no>126</Page_no><display_no>110</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[110 PEARSON science NEW SOUTH WALES Practical investigations3.2 Energy from food (biomass) The stored chemical energy in food can be used to produce biofuels. Food is also used to produce chemical energy inside your body. Purpose To burn a sample of food and calculate its energy content. Materials • food samples (such as Cheezels, crusty bread, Marie biscuit) • cork • aluminium foil • paper clip • retort stand and clamp • thermometer • test-tube • electronic balance • small measuring cylinder Proce$:$zXeMEMW1S7++0n4xM4cVm1nL/Hrc/0/jHoaP92m+j8RsABdeBd3jaba7TFgq1CWHqtxSH5HrIgrI
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LwMdEJHtJ4VoowxmgXNx7+gxHvN8FHlUYCRc+H/1EQ==$:$ towards the centre of the pinwheel. iv Secure the corners at the centre using a nail or drawing pin. v Press the nail into the bamboo skewer. 2 Design an experiment to test the speed at which the turbine will spin when wind hits the turbine from directly in front or when it hits from an angle. Figure 3.2.21 may give you some ideas. 3 Write your procedure in your workbook. 4 Before you start any practical work, assess your 2 SAfeTy A Risk Assessment is required for this investigation. Do not operate the hairdryer near water or insert any materials inside the fan. Use this template to make your pinwheel ‘turbine’. Figure 3.2.20 procedure. Assess any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required materials and start work. Results Present your results in a table. Practical review 1 Construct a conclusion for your investigation. 2 Assess whether your hypothesis was supported or not. cardboard pin wheel bamboo skewer string paper clip make sure cylinder is secure holes in cylinder If the cylinder is unstable, tape it to a thick cardboard base so it is sturdy when standing upright. Figure 3.2.21 ]]></TextData></Page><Page><Page_no>128</Page_no><display_no>112</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[112 PEARSON science NEW SOUTH WALES Water is one of the most important substances on Earth. Water is present in the atmosphere, on the surface of the land and underground. About 70% of the human body is made up of water. Humans can survive for weeks without food but only a few days without water. The water cycle3.3 Water on Earth Look at the map of the Earth in Figure 3.3.1. It shows that there is far more water than land. About 70% of the Earth’s surface is covered by water. However, almost all (97.5%) of the water that covers Earth is in oceans and salt water lakes. This makes it unsuitable for drinking and most other uses. The other Seventy per cent of the Earth’s surface is covered by water. Figure 3.3.1 science fun Dripping glass Where did the water on the outside of the glass come from? Collect this… • cold water from the fr$:$zFLT85hl1ARH+YtXasp6iCZa3xmMbeRUkvWSpUli2ig0pYl/ooCQ2rSlSbtksiFYnpY8aOY1wfsb
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ARYkTewOja8nWYa5A9gHkbpMB/QA+JX7l9i1BPjxib8nn/8ZwmOH6SXW1mvgI54=$:$ energy from the Sun causes water to evaporate from bodies of water such as the ocean, rivers and lakes. Liquid water in the ocean has changed into water vapour in the atmosphere. As the water vapour rises, it cools. At a certain height the air cannot hold any more water vapour and the air is said to be saturated. Any further cooling causes water vapour in the air to condense, changing into tiny drops of liquid water. These tiny droplets form clouds, like the one in Figure 3.3.4. renewable fresh water— the water on Earth available for our use (0.01%) oceans (97.5%) ice and underground water (2.5%) The amount of water on Earth available for our use is very small compared to the total amount of water on Earth. Figure 3.3.2 ]]></TextData></Page><Page><Page_no>130</Page_no><display_no>114</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[114 PEARSON science NEW SOUTH WALES As Figure 3.3.6 shows, tw$:$p6lwmKrirSQ2xZpYmwmHwYakwVNq2629upGiIuVvOouhrY9MSnm84NgnSXtvIX68QgTTmX1Mehdo
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8YLlgDbHTQq8$:$n causes some of this water to evaporate from the stems, flowers and leaves of plants. The process of the evaporation of water from plants is called transpiration. It is shown in Figure 3.3.7. About 10% of the water vapour entering Earth’s atmosphere comes from transpiration. river precipitation R U N - O F F P E R C O L A T I O N soil Once precipitation has landed on Earth it may flow over the surface or percolate into the soil and rocks beneath. Figure 3.3.6 Animals drink fresh water from rivers and lakes. This water is returned to the atmosphere as it evaporates from their bodies, or returned to the ground when it is excreted (removed from their bodies) as urine. Putting all these processes together creates the water cycle, as shown in Figure 3.3.8. TRANSPIRATION water in soil water travels up through trunk Transpiration is the evaporation of water from leaves and other parts of a plant. Through transpiration, water is carried from the soil and returned to the atmosphere. Figure 3.3.7 3.5 3.6Prac1 p. 120 precipitation precipitation condensation evaporation evaporation run-off transpiration percolation The water cycle Figure 3.3.8 ]]></TextData></Page><Page><Page_no>131</Page_no><display_no>115</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 115 Groundwater Rainwater, rivers and dams are major sources of water for Australia. However, more than 20% of the water used in Australia each year comes from groundwater. Groundwater is water that exists underground. Most groundwater is not in underground lakes or rivers but is trapped in the tiny spaces between grains of sand or within pervious rocks. Pervious rocks are rocks that allow water to soak into them. Pervious rocks contain tiny spaces into which water can soak. Figure 3.3.9 shows how this works. When the $:$J+T35xRKxlgnHLjr3BzDjPqzwdy2/DvNkGSoXVrV13ir3I8Y40YCT1hY+IsaNCOEP0fYcsG7dHDn
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nZOboJHW0UWgFwg=$:$ious and impervious rocks. Water is extracted from the pervious rocks using aquifers. These aquifers supply water to large areas of inland Australia. Figure 3.3.10 Australia is sitting on top of it. Many millions of years ago there was an inland sea in Australia. Under this sea, rocks formed in alternating layers of pervious rock and impervious rock. Impervious rock does not allow water to soak into it. Movement of the land has exposed areas of the pervious rock. Water can soak into the pervious rock and flow underground. The impervious rock prevents the water from escaping. The result is a very large store of groundwater—the Great Artesian Basin. You can see its structure in Figure 3.3.10. It takes a very long time for the water to soak through the rock and into the aquifers. Some of the water in the Great Artesian Basin has been there for millions of years. Factors affecting the water cycle Many natural factors influence the rate at which water moves through the water cycle. It can take a few days to thousands of years for an individual particle of water to move through the water cycle. In that time the water goes from ocean to atmosphere to land and back to ocean again. Some of it slowly seeps through the rocks and is then trapped underground. This water is still part of the cycle but will not move on to a different stage until the water is carried up to the surface through a bore or well. States of water The water that is trapped as ice at the North and South poles, in glaciers and on the top of high mountains is also part of the water cycle. The water in the ice and snow of Figure 3.3.11 on page 116 cannot move on to the next stage until it melts. Unit 2.3 Prac2 p. 120 ]]></TextData></Page><Page><Page_no>132</Page_no><display_no>116</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[116 PEARSON science NEW SOUTH WALES Humidity Humidity is the amount of water vapour in the air. Water vapour can be added to the air until the air becomes saturated. When this happens, the air cannot hold any more water vapour. As the air above a surface reaches saturation point the rate of evaporation (and transpiration) slows down and stops. You may have experienced the effect of saturated air. When you sweat on a hot day with low humidity, the sweat dries (evaporates) off your skin quickly and cools you. However, if the air is very humid then the sweat remains on your skin and you feel hot and sticky. Air movement Air moving across a wet surface increases the rate of evaporation. Moving air carries away the saturated air, allowing evaporation and transpiration to continue. This is why turning on a fan makes you feel cooler and more comfortable on a hot, humid day: the breeze blows away the saturated air allowing your sweat to start evaporating again. Figure 3.3.12 shows how this happens. Prac3 p. 121 moist surface moist surface wind slow evaporation saturated air rapid evaporation If wind blows away the saturated air, the rate of evaporation increases again. If there is no wind, the air above a moist surface can become saturated. Air becomes saturated and evaporation is slow if there is no wind. Wind blows away moist air and so evaporation increases. Figure 3.3.12 Ice cannot be taken up by plants. Many trees living in areas where water in the soil is frozen for part of the year are deciduous. Deciduous trees lose all their leaves in winter. Without leaves there is very little transpiration. Without leaves the trees are able to survive until the weather becomes warmer and water becomes liquid again. Air temperature Air temperature affects the rate of evaporation from bodies of water and soil. It also affects the rate of transpiration. As$:$a+RWCPbLb0ulv5z4E6JkylHw5u74DJGMMQNHZMGBRJL5Y3fbkA4rbWBwMGun/+xeR9obTCcLMXy2
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IEp5SDOP2vws8hlqdZZeIBkbzg==$:$nk there may be liquid water on Mars. NASA photographs have revealed soil deposits, suggesting that water had carried sediment through two small valleys in the time between the Mars mission in 2005 and the next Mars mission in 2012. Analysis of rock samples collected by the Mars Curiosity Rover in 2013 provided evidence that in the past, water on Mars may have been good enough to drink. ]]></TextData></Page><Page><Page_no>133</Page_no><display_no>117</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 117 Landscape Topography is the hills, valleys, rivers and other physical features of the landscape. The topography of an area affects run-off and percolation. Rain falling on smooth rock and steep slopes (such as the one in Figure 3.3.13) will quickly run over the surface and into streams and rivers. These streams and rivers will move the water quickly back into the ocean. Where there are broken rock surfaces$:$c8ELgGSNV5GvhJovT/8lexKt9gEwVdytXOAGIRm4fnECigeZqE1k4cUtXgN2cIBHf/2+GU98Y7yr
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IxIja2aOJCrB3+Fkm1fd0C20/kzQNgXK1OQb6LcnGyexZaj6R6UaxA==$:$ is recycled. 11 For the science4fun on page 112, predict what would happen to: a the outside of the glass b the level of water in the glass. Applying 12 Identify the process that moves water from: a rivers to the atmosphere b oceans to the ice cap at the South Pole c the atmosphere to freshwater lakes d surface water to aquifers e surface water to rivers. 13 Use diagrams to demonstrate how water droplets in a cloud develop into rain. 14 Sketch a simple version of Figure 3.3.15 and use it to demonstrate what would happen to water that fell on the piece of ground represented by the diagram. L ground surface Figure 3.3.15 Analysing 15 Compare: a evaporation and transpiration b pervious and impervious rocks c percolation and run-off. 16 Use the table below to answer the questions that follow. Water source Percentage of total water Oceans 97.24 Rivers and freshwater lakes 0.01 Inland seas 0.008 Ice caps and glaciers 2.14 Soil moisture 0.005 Groundwater 0.61 Atmosphere 0.001 a Oceans are the largest source of water on Earth. Identify the next largest source of water. b Identify which holds more water, the soil or the atmosphere. c Compare the amount of water in inland seas, and in freshwater lakes and rivers. 3.3 ]]></TextData></Page><Page><Page_no>135</Page_no><display_no>119</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 119 17 Compare the formation of clouds in the atmosphere with the formation of water on the outside of a glass or can of cold soft drink. Evaluating CCT 18 a Propose how you would respond to someone who says that all the water you use is recycled water. b Explain your response. 19 a Deduce which set of conditions shown in Figure 3.3.16 would cause the greater rate of transpiration. b Justify your answer. 20 a Deduce which set of conditions shown in Figure 3.3.17 the would dry the washing quicker. b Justify your answer using your understanding of the water cycle. Figure 3.3.16 Figure 3.3.17 Creating CCT 21 Construct a diagram that demonstrates how the cloud on top of the mountain in Figure 3.3.14 on page 120 could have formed. 22 Construct a bar or column graph to accurately show the information in the table in question 16. N 23 Use information from this unit to construct a pie graph (sector graph) showing the different percentages of water on Earth’s surface. Inquiring 1 More than 97% of all water on Earth is sea water. It would be very useful if we could drink it but we can’t. Research to find out: • how sea water compares with the water we drink • what would happen to your body if you drank it. Present your research as a series of tables, labelled diagrams and/or graphs. 2 Some parts of the world have very cold winters. In these places lakes and ponds may freeze. Research what happens to fish and other living things in these bodies of water. Find out: • which part of the water freezes $:$2rPWQJMVLodz5+qZCGkcPf+ZAR4FWQX4VOL4nk/3Gbpf7O0d8dzxARtOM031u5wG4rYmhNeFmpVK
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arERYqSvLegGipcpajIyRu2+F82Arxf+sz5ty+TbjdPNLuz9jtmxbW+qidY9vAFMN50AlQ==$:$ise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect the required materials and start work. Practical review 1 a Calculate the amount of water lost from each container. b Compare the amount of water lost. 2 Compare your results with the results from other groups. 3 Identify any factors that you were not able to control that might have affected your results. 4 a Construct a conclusion on the effect of sun and shade on the rate of evaporation. b Assess whether your hypothesis was supported or not. 2 Fill the gravel beaker with gravel until it is half full. Gently tap the side of the beaker to settle the contents. Add more gravel if necessary. 3 Fill the sand beaker with sand in the same way. 4 Add some clay soil to the clay beaker and push it down firmly. Add more clay soil and push it down again. Repeat this process until the beaker is half full. 5 Measure 100 mL of water and pour it into the top of the gravel beaker. Pour it over the whole surface, not just in one place. Observe what happens for 5 minutes. 6 Repeat step 5 for the other two beakers. Results 1 Record your observations of the way the water percolates through the three different materials. 2 Record whether any of the materials had water lying on the top after 5 minutes. Practical review 1 Propose why it was necessary to push the clay soil down firmly instead of just tapping the side of the beaker. 2 Identify the material through which percolation occurred most quickly. 3 Identify the material through which percolation occurred most slowly. 4 Explain why the different rates of percolation occurred. 5 a Identify the material from which run-off is most likely to occur. b Justify your response. 6 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. ]]></TextData></Page><Page><Page_no>138</Page_no><display_no>122</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[122 PEARSON science NEW SOUTH WALES In nature plants and animals get water from rain, rivers and natural stores such as lakes. In modern society, water is needed for cities, industry and agriculture. To meet the needs of modern society, water resources have to be managed differently. This management changes the movement of water through the water cycle. Water management3.4 science fun Ants and water Can ants help locate a water source? Collect this… • shallow container for water Do this… 1 Fill the container with water. 2 Place it on a path or on the grass in a partially shaded part of the garden. 3 Leave the container undisturbed for about an hour. Record this… Describe any change in the behaviour of ants in the area. Explain why this happened. Storing water in dams Australia is the driest permanently inhabited continent.$:$vVJdZx+q0abIURPydrTlnl3VY+r/FaewiIT6RUjKFFn3tUa2U9kiNY26hcPgyRALfoOAUBxtLein
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JTl4MTSSz0vGafR8ShkWlhWzac6LpFUXWVM=$:$d store water to be used by industry and households in the cities. All ice, no water! Australia might be dry but the continent of Antarctica is even drier! This is because all of its water exists as ice. The constant freezing temperatures never allow the ice to melt. ]]></TextData></Page><Page><Page_no>139</Page_no><display_no>123</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 123 All dams interrupt the water cycle because water stored in them does not flow down the river and into the ocean. Water from the surface of the dam evaporates and is returned to the water cycle. However, in a very deep dam some water may not be available for evaporation for a very long time. Irrigation Most of the farm crops grown in Australia have been introduced here from other parts of the world. This means that they do not have characteristics that allow them to grow with only small amounts of water. These crops need continuous supplies of water and farmers provide this water through irrigation. Irrigation is a practice used in agriculture that provides water to crops using pumps, pipes and ditches. That’s big! The tallest dam in the world is the Nurek in Tajikistan in the Himalayan Mountains. The dam wall is 300 metres high. In 2014 when the Jinping-I Dam$:$wjPoBT9g/SGavRvtVedVn6dLZkTotpDxXApb0S55WIgax7H3yTD+sXBNl8F0YM+cvsD8w1iVnnRu
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N3uFvDRe1UmfW5yeZzM0lyImGki2YYHZVUJRb/u7At45ZVUQkjAX$:$moves up through the plant and is eventually lost back to the atmosphere through transpiration. There are some differences between spray irrigation and rain. When it rains there are usually clouds in the sky and the air is very humid. These factors reduce the rate of evaporation. Spray irrigators may be used on hot days when there is bright sunshine. The tiny droplets of water produced by the spraying equipment evaporate quickly in hot, dry air. Water landing on the leaves also evaporates more quickly than in a natural rain storm. Therefore a lot of the water that would normally percolate into the soil evaporates into the atmosphere instead. Spray irrigation is like having rain fall on the crop whenever it is needed. Figure 3.4.2 ]]></TextData></Page><Page><Page_no>140</Page_no><display_no>124</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[124 PEARSON science NEW SOUTH WALES Flood irrigation In flood irrigation, water is released into channels between the crop plants. This is shown in Figure 3.4.3. The water percolates into the soil to the plant roots. However, the water will evaporate quickly if the soil and irrigation channels are not shaded. With flood irrigation the water reaches the roots. However, if ther$:$QQ37SKSA9iXjHxUvra24SC6IDL/35plGuo0+/0F8eN1R98IRu3qBjx9fUR1lPbjLJ+T35xRKxlj6
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kD5/YP9stx67V6owaZL222E5LnJX$:$Mountains Scheme is one of the largest irrigation projects in the world, with about 225 km of tunnels and pipelines. Figure 3.4.4 River Snowy River Murray River Lach lan River Murrumbidgee Leeton 0 40 N 80 km Canberra Melbourne Wagga Wagga Albury Murrumbidgee Irrigation Area Snowy Mountains Scheme Griffith New South Wales Victoria Australian Capital Territory Map showing the locations of the Snowy Mountains Scheme and the Murrumbidgee Irrigation Area. Figure 3.4.5 The water is used to irrigate large farming areas in the Murrumbidgee Irrigation Area. Irrigation has enabled this area to become one of the main wine and food producing parts of Australia. Water that once flowed very quickly into the ocean is spread across land that is naturally dry. The water used for irrigation is returned to the atmosphere through transpiration and evaporation from soil. Irrigation water also percolates through the soil into the groundwater. Eventually the excess water flows via the Murrumbidgee and Murray rivers into the ocean on Australia’s southern coast. Meanwhile the Snowy River carries only 1 per cent of its original flows. This has affected ecosystems along the banks of the river. Using stormwater Building cities replaces pervious soil with impervious concrete and bitumen surfaces. Water that lands on soil percolates about 15 mm into the ground before there is any run-off. Water that falls on roofs, roads and footpaths runs off immediately. The water flows into stormwater drains (like the one in Figure 3.4.6) and out to the ocean. ]]></TextData></Page><Page><Page_no>141</Page_no><display_no>125</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 125 channels from the city carry run-off from the city streets into the swamp. When it rains, the stormwater flows to Baldwin Swamp, carrying with it rubbish and pollutants. The rubbish has to be collected by City Council workers. Natural processes in the wetland absorb pollutants from water and improve the quality of the water before it flows out into the river and ocean. The ability of wetlands to clean water has been used by city councils and land developers in projects such as rain gardens. Baldwin Swamp in Bundaberg is a natural wetland that is hom$:$bApZxwDuZ0tzMSnl3RKS1AAU4wdX3B7lLUIElwT4GImtX4R20zHM1AHRosdlswfOlhDPQS/JAKz7
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hdCHtP6rPDOOLFpToe7Ve2xWE8/eRcC2P66GHrp8fl9a$:$ater and then it is used to irrigate parkland and sports fields and to water trees in the city. In the city of Orange in New South Wales, some of the water that flows into Blackman’s Swamp Creek during storms is captured and then transferred to a nearby dam. Figure 3.4.7 shows how much water flows out during such a storm. All this stormwater is now collected, increasing the water supply for the city. Baldwin Swamp is a natural wetland in the Queensland city of Bundaberg (Figure 3.4.8). As well as being a habitat for a wide variety of birds and animals it has another important function. Three main drainage A large amount of water flows along Blackman’s Swamp Creek during a storm. Figure 3.4.7 ]]></TextData></Page><Page><Page_no>142</Page_no><display_no>126</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[126 PEARSON science NEW SOUTH WALES Rain gardens Rain gardens are a much smaller scale way of dealing with stormwater. Figure 3.4.9 shows how rain gardens slow down the rate of flow and clean pollution from the stormwater before it enters creeks and rivers. Stormwater is channelled into the rain garden bed. In the garden bed is a layer of sand that filters the water. The filtered water is similar in quality to the water in undisturbed streams. It is not drinking quality but it is suitable for irrigation. Rain gardens can be landscaped into suburban gardens as well as city parks, school yards and large nature strips that divide freeways. Figure 3.4.10 shows a working rain garden. downpipe directs stormwater to rain garden plants overflow pipe soil and sand filter coarse sand perforated pipe collects filtered water stormwater pipe water collects on top of garden in times of heavy rain water filters through A rain garden cl$:$irBbNafVlqGCDDRqgKJIyx9fo8thWzCTKqG/lU9EIhSNK2lUKWL8YWTh/Kc3JAhyVV47gdrXb5CN
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7mvGANnAyA==$:$ movement of water over the land surface is changed. Trees, shrubs and long grass slow the rate at which water can flow over the ground. This means that there is more time for the water to soak into the soil. In the absence of vegetation, water moves quickly over bare ground and often carries large amounts of soil. This eroded soil is carried with the water as it flows into streams and rivers. Figure 3.4.11 shows the effect of this fast-moving water. Unit 3.1 Prac2 p. 132 Prac1 p. 131 These channels in the soil (known as rills) have been created by erosion of soil by fast-flowing water. Figure 3.4.11 3.83.7 ]]></TextData></Page><Page><Page_no>143</Page_no><display_no>127</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[indigenous water use Earth resources 127 the CurriCulum learning aCross aboriginal anD torres strait islanDer histories anD culture Indigenous Australians are able to live in some of the driest parts of Australia. They can do this because they are able to use their observations to find sources of water. In the middle of a dry area, ghost gum trees (such as the one in Figure 3.4.12) indicate where there is underground water. Ant trails also lead to underground water and dingo tracks lead $:$ek3OJEA6ecisx5hiFFqkWUqJ/NO9Yo/wh/jMn2jXmrROcA9rrY+cHRTrMnUqwdZo6V3gezUvlGpv
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FdkqlIL+nd9QS+WPu1f048eIk96zn8cQJEGnZp5SY3dXBAej3m+k5jqKv9IiT4tgX11U$:$ation of water sources determined the routes Indigenous Australians used to travel around the country. Markings such as these in Figure 3.4.13 were made on the rocks to indicate where water could be found. In this way they were sure to have reliable sources of water. These circular rock markings show that a number of waterholes are nearby. Figure 3.4.13 A mature ghost gum has a thick trunk that is covered in very white bark, giving it its name. Its presence indicates that water is nearby. Figure 3.4.12 ]]></TextData></Page><Page><Page_no>144</Page_no><display_no>128</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[128 PEARSON science NEW SOUTH WALES There are many springs where water from the Great Artesian Basin comes to the surface. One is shown in Figure 3.4.14. These springs were a major source of water for Indigenous Australians and for native plants and animals. Some European explorers and early settlers learned how to find water from the Indigenous people and so they too could get their water from springs. In general, non-Indigenous Australians see water as a resource to be used. Indigenous Australians also view water as essential for survival but it is also an important part of their culture. There are many ceremonies, songs and customs which have been followed for thousands of years to make sure that rains come to keep the land, plants and animals healthy. Early explorers were glad of the help Indigenous Australians could give them. However, Indigenous knowledge of land was not valued when decisions were being made about development of land and use of water. This is beginning to change as decision makers develop a respect for Indigenous knowledge. For example, in the Kimberley region of Western Australia the knowledge of the wetlands held by the Karajarri people was almost the same as the information required by the scientists studying the area for possible development. However, the Karajarri described the information in a different way. Indigenous Australians are now involved in decision making relating to the use of water and any developme$:$j8EdR38rOkusX+V3gVxxpsobXyDqe2qROywI4pYy4lSJaeJZ/SanAwR1+XFwzzZEHAGjsb+OH2ei
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AWiV2V/742UT2g==$:$ully place your bag over the twig so that a number of leaves are enclosed as in Figure 3.4.19. The twig must still be attached to the tree. 4 Use the string to tie the bag on tightly. 5 Leave the bag in place for 24 hours. 1 branch with fresh leaves plastic bag tie Figure 3.4.19 Results 1 After 24 hours remove the bag from the twig. Be careful not to lose any of the water. 2 Carefully pour the water into the measuring cylinder. 3 Record the amount of water collected. Practical review 1 Explain how the water got into the bag. 2 Describe how the humidity inside the bag would have changed during the 24 hours of the experiment. 3 Propose how this change in humidity could have affected the amount of water collected. 4 Demonstrate how the information you have collected relates to the water cycle. 5 Predict how much water you would collect after two or more days. If your teacher agrees, carry out an investigation to test your prediction. ]]></TextData></Page><Page><Page_no>148</Page_no><display_no>132</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[132 PEARSON science NEW SOUTH WALES Practical investigations STUDeNT DeSIGN 3.4 More water from leaves Purpose To investigate factors affecting water loss from leaves. Hypothesis What factors do you think will affect the amount of water lost from leaves—amount of sunlight, leaf type and number or some other factor? Before you go any further with your investigation, write a list of factors and how you think each one will affect the amount of water lost. Write your hypothesis in your workbook. Materials Materials as per prac 1. Procedure 1 Design an experiment that compares the amount of water lost from leaves in different circumstances. Before you start work, first decide on which factor or variable you are going to test. You might try: • leaves in the shade and in bright sunlight • old and young leaves • Australian n$:$4P55ySmwK9p1orQ9XBDjnTigX5zaQ/yfqDzFjY/utcjld3ceKBNYJY0wDjXeNsGozGa7SPmv4K4i
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USEM3fPgug==$:$ht involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required materials and start work. Hints Make sure you only change one variable (such as sunlight). Keep all the other variables (such as type of plant and number of leaves) the same. Results Record your observations in your workbook. Practical review 1 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. 2 a Evaluate the procedure used in your experiment. b Describe what could have been done to improve the outcome. Will leaves in sunlight or shade lose water faster? Figure 3.4.20 ]]></TextData></Page><Page><Page_no>149</Page_no><display_no>133</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Earth resources 133 Chapter review3 Remembering 1 Name the following: a The process of small particles of rock being carried away from the parent rocks by wind, water and ice. b The process of re-using materials rather than disposing of them and then having to make more of them. c A natural resource that is replaced by natural processes at about the same rate at which it is being used. 2 List ten devices that may be found in your home that use energy but did not exist 50 years ago. 3 List the three changes of state that water passes through in the water cycle. Understanding 4 Modify the following definitions to make them correct. a A natural resource is a substance supplied by the Earth for humans to make products they need. b A renewable natural resource is one that is replaced by natural processes that occur on Earth on a timescale much longer than a human life. c Deposition is the process by which sediments are carried away by a moving stream of water, air or ice. 5 Explain the adv$:$n6exqQj5/oit4y37wFtnQFDbymWTfecoHOThLF2INZa+bVVHgYzambWoz5kGM5gLAaz4osE97/bX
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vMNQI/mppXdOe/Wt+BQ=$:$ increased throughout the world, the rate at which water moves through the water cycle would: A stay the same B decrease C increase D increase in some areas and decrease in others Q5 As water goes through the water cycle again and again, the amount of water on Earth: A increases B decreases C stays the same D varies from time to time Q6 An experiment testing whether oxygen in air can be renewed was set up as in the diagram below. The flasks were placed in strong sunlight for a day. The gas collected in test-tube A made a glowing splint ignite. From the results, you could conclude that: A sunlight turns water into oxygen and carbon dioxide B plants take in oxygen from the air and give out carbon dioxide C plants produce oxygen if they have sunlight and carbon dioxide D all the oxygen in the atmosphere comes from green plants CCT CCT gas Flask A plant, water, carbon dioxide and light Flask B plant, water and light, no carbon dioxide Flask C plant, water and carbon dioxide, no light sunlight CCT ]]></TextData></Page><Page><Page_no>152</Page_no><display_no>136</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[136 PEARSON science NEW SOUTH WALES Glossary Unit 3.1 L Atmosphere: layer of gases above the Earth’s surface Coal seam gas: natural gas released from coal by fracking Deposition: the process in which sediments drop out of a moving stream of water, air or ice Erosion: the removal of sediments away from the place of their formation or deposition Fracking: a form of mining in which water and other chemicals are pumped into rocks, causing them to fracture (break) and release the non-renewable resource Humus: decaying plants and animals and their wastes Igneous rock: rock formed by the cooling of molten rock, for example basalt Minerals: substances found in rocks Non-renewable resource: a resource that takes longer than the average human lifespan to be replaced Photosynthesis: the process by which plants use carbon dioxide, water and sunlight to make food Renewable resource: a resource that is always being replaced naturally Resource: something that satisfies a particular purpose or need Sediment: material such as silt and sand that is transported and deposited by water, ice and wind and forms layers on the Earth’s surface. In time it can become compacted to form sedimentary rock Sedimentary rock: rock formed by compacting and sticking together of sediments, for example sandstone Weathering: the process of breaking rocks down into smaller pieces Erosion Igneous rock Renewable resource Unit 3.2 L Biofuel: fuel obtained from plants, agricultural waste or algae Biogas: a gas produced from the fermentation of organic waste, such as waste from sugarcane, and used as fuel Biomass: all plant and animal matter found on Earth Carbon capture and storage: the process whereby carbon dioxide gas is isolated and captured for underground storage after coal is burnt Fossil fuels: fuels such as coal, oil and natural gas, formed from the remains of living things buried millions of years ago Geothermal energy: energy sources from heat below the Earth’s crust Greenhouse gas: ga$:$8FAT/POliAZg9/O/RRQWC87KmgxRypCKHA0+j6RlwRKSPLeTgtwQ7fmh3I1gOEOwTG+iACKz15YT
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1dTn1GGWVoVZIkKReg4IYCPgqCAwGw==$:$tainers with lids (such as pill bottles) Do this… 1 Pour about 5cm of water into each container. 2 Add about 5 drops of detergent to one container. Mark the container so that you remember that it contains detergent. 3 Pour about half a centimetre of oil into each container. 4 Put a lid on each container and shake each for about 20 seconds. Record this… Describe what happened. Explain why you think this happened. Types of mixtures What is a mixture? Paints, drinks, foods, seawater and air are not pure substances; they are mixtures. In science a mixture is a substance made from two or more pure substances or pure chemicals that have been stirred together. For it to be called a mixture, you must be able to separate them again. Solutions Watch carefully as sugar is stirred into water and the solid sugar will seem to disappear! The sugar has dissolved. The sugar breaks up into tiny particles that are too small to see. These particles then spread throughout the water. Although these sugar particles cannot be seen, the sweetness of the liquid tells you they are still there. This is what is meant when something is said to dissolve. A substance that dissolves like this is described as soluble. A substance that does not dissolve is described as insoluble. When things mix really well, like when sugar dissolves in water, the mixture is known as a solution. When you stir sugar into water, you make a sugar solution. Prac1 p. 145 Mixtures 139 ]]></TextData></Page><Page><Page_no>156</Page_no><display_no>140</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Solutes and solvents When you make a solution, the substance that dissolves is known as the solute. In a sugar solution, the sugar is the solute. The substance that dissolves the other one is the solvent. So in this case the water is the solvent. The soft drink in Figure 4.1$:$tAgcJlSPoxLcUc1d+d0sq+h2Ozt/exeC0axldQ/mTK9g/nx0L6v9Rj6ifi48BjOkO3MBD2RwFJsS
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ds7Ua0kSDQtlo+qSdk2zIkoqH2LgtNIkTndjtA==$:$pour dissolved in the other gases of the air Most of the solutions you will meet in science and at home are aqueous solutions. An aqueous solution always has water as its solvent. Sugar dissolves in water, so a sugar solution is classified as an aqueous solution. Likewise, soft drink is an aqueous solution of sugars, preservatives, flavouring and carbon dioxide. Soft drinks have liquid water as their solvent. Dissolved flavourings, sugars and preservatives give the soft drink its sweetness, colour and taste. The carbon dioxide gas bubbles to the surface when you release the pressure in the bottle by removing the lid. Figure 4.1.1 A particular solute will dissolve in some solvents and not in others. For example, grease will not dissolve in water but will dissolve in the fluids used by drycleaners. Particular solvents will dissolve some substances and not others. For example, water will dissolve detergent, but not oil. You can see this in Figure 4.1.2. Solution or not? Light passes easily through a solution, allowing you to see through it. This is one way of telling whether a mixture is a solution or not. Solutions are transparent (see-through). You can describe solutions such as this as ‘clear’, meaning you can see through them. Solutions can be colourless, looking much like water. Other solutions are coloured. For example, blue copper sulfate solid dissolves in water to form a blue-coloured solution. You know that a solution has been formed because you can see straight through it. You can see its preparation in Figure 4.1.3. Oil will not dissolve in water but detergent will. Figure 4.1.2 oil in water detergent in water solvent (water) solute (copper sulfate) solution (aqueous solution of copper sulfate) Preparation of an aqueous solution of copper sulfate Figure 4.1.3 140 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>157</Page_no><display_no>141</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Colourless and clear are not the same. Clear means that you can see though it. Colourless means it is not coloured. Figure 4.1.4 helps explain these different meanings. Dilute, concentrated and saturated solutions A solution is said to be concentrated if there is a lot of solute dissolved in the solvent. If there is only a little solute in the solution, then it$:$3IGzYnyWukx8jhF35lSRzJqsUH7J8S4c2t4cwZREkDn0EQ9/M/yy/uuYrY+Llxv07wRyV5zt0Zcw
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TMmgqJJ+jave1spGUV0dzEpl0tUSinNd$:$r and kept adding spoonsful of salt to it, stirring each time. You would find that eventually the salt would stop dissolving. When a substance will no longer dissolve in a solvent, the solution is said to be saturated. Any undissolved solute then falls to the bottom as sediment. This is shown in Figure 4.1.6. 19 spoonsful added2 spoonsful added saturated solutionunsaturated solution sediment (undissolved solute) solvent (water) The solution that is saturated with salt has the higher concentration—so high that no more salt will dissolve. Figure 4.1.6 Concentrated solutions have a lot of solute dissolved in them while dilute solutions have very little. Figure 4.1.5 solute solvent concentrated dilute solute solvent concentrated dilute Shake your bottle Many medicines need to be shaken up before you take them. If you don’t, then one of the important ingredients in the medicine might remain as a sediment on the bottom of the bottle and so you would receive an incorrect dose. That is why you are told to ‘shake the bottle before using’. Mixtures 141 ]]></TextData></Page><Page><Page_no>158</Page_no><display_no>142</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[In the natural world, solutions sometimes become saturated. This can cause solid salt to be deposited (left behind) around the edges of salt lakes when the salt reaches a high concentration. The solution becomes saturated because of the water evaporating and also because of high levels of salt entering the lake. Figure 4.1.7 shows Lake Gairdner, a salt lake in South Australia. Salt crystals often form around the edges of salt lakes. Figure 4.1.7 Prac2 p. 146 Prac3 p. 147 4.1 Sweet tea! If you tried to saturate a hot cup of tea with cane sugar (sucrose) then you would need to add about 700 g or 100 teaspoons of sugar! Your cup would overflow long before the tea became saturated. Suspensions Sand does not dissolve when it is mixed into water. Instead it stays solid and spreads throughout the water. This type of mixture is called a suspension. In suspensions, substances like sand do not dissolve but disperse (spread) through a liquid or gas. Figure 4.1.8 shows dust floating in the air. This is another example of a suspension. Usually, the suspended particles are too large and heavy to stay in suspension and will fall and settle if left undisturbed. Sand mixed into a beaker of water will, after a while, settle on the bottom of the beaker. In the same way, dust in the air eventually drops to cover floors and other surfaces.Table 4.1.2 lists some differ$:$SC+Z4UQIIkjTqvuCobt5yk8Y+e0xi4B8JnLEQUciEx2n3o9Mj7pFHMRbJa7Vqdu8XLjXDnMuj2Ui
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Mb/N0avCuSGU07T8yUdV$:$ liquid in another. Dust floating in the air forms a suspension of a solid (dust) in a gas (air). Eventually, the dust will settle onto the furniture. Figure 4.1.8 4.2 142 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>159</Page_no><display_no>143</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review4.1 Remembering 1 List two examples each of a solute, a solvent and a solution. 2 List four types of solution and give an example of each. 3 List three types of suspension and give an example of each. 4 Recall the correct names for these mixtures. a A type of mixture in which one substance does not dissolve in another but quickly separates out to form a sediment b A clear mixture in which a substance dissolves in another Understanding 5 Explain why cooking oil forms clumps of drops when added to water but seems to ‘disappear’ when added to detergent. 6 Define the term concentrated solution. L 7 Mylanta® is an antacid liquid used to relieve heartburn. The label tells you to shake the bottle well before use. Explain why. 8 Outline how you could show that a sugar solution is just saturated. Applying 9 A chef dissolved salt in boiling water that he was going to use to cook pasta. Identify whether the salt, water or salty water was the: a solute b solvent c aqueous solution. 10 Identify a solvent that will dis$:$3BFOQiOn9zIf+r98R9SBRMy1SOB9PmLGK0I7jpoo3tsShxCUHwgieKScw5nTBy+fUmxzBU+bujYx
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xQ4C6vsekQ==$:$ssify each of the following as a solution or a suspension. a cordial in water b carbon dioxide gas in lemonade c clouds d food colouring in water e dust in air f smoke from a car exhaust Evaluating CCT 16 Fiona found that 10 mL of water tasted just as sweet whether she mixed 5 teaspoons or 10 teaspoons of sugar into the liquid. Propose an explanation for this. 17 Figure 4.1.9 shows milk being poured into salt water. a Identify which substance is the solution. b Justify your answer. Figure 4.1.9 Mixtures 143 ]]></TextData></Page><Page><Page_no>160</Page_no><display_no>144</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review4.1 18 Vitamin C in food is soluble in water. Vitamins A, D and K are soluble in oils. Chefs recommend that: • vegetables are not soaked in water before or during cooking • steaming or microwaving is better than boiling. One reason for these recommendations is to stop heat destroying the vitamins. Propose another reason. 19 Figure 4.1.10 shows beams of sunlight passing through foggy air. a Identify whether the air is a solution or a suspension. b Justify your answer. 20 Solutions are tran$:$rGaIjl5VuANcDrD/PR4Wx16XOmclbCLHxzU8JP0rM9FUfmYzqyUIYAnUhwyHAW6r747zigezhdxl
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9z4yPbk=$:$ to find the exact time each tablet takes to dissolve. Results Record which tablet (whole or crushed) dissolved first. If you measured the time taken for each to dissolve, then record the times as well. Practical review 1 List the variables that you controlled (kept constant) during this experiment. 2 State the variable that you changed. 3 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. 4 In this investigation, it was not necessary to measure the length of time it takes for the two tablets to dissolve. Explain why. 5 A crushed Sugarine tablet has more surface area and more contact with the water than a whole tablet. Use this information to explain your results. 6 You sometimes take an aspirin tablet or capsule when you have a bad headache. Capsules contain roughly the same amount of aspirin as a tablet. However, a capsule has its aspirin as small particles held in a shell that dissolves when you swallow it. a Assess whether a tablet or a capsule would go to work on your headache faster. b Justify your answer. 2 Safety A Risk Assessment is required for this investigation. 146 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>163</Page_no><display_no>147</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[StUDeNt DeSIGN Investigating dissolving Purpose To investigate how things dissolve. Hypothesis Once you have decided which investigation to perform, write a hypothesis in your workbook. Materials Students to choose from: • sugar • copper sulfate (CuSO4 ) • salt • 3 varieties of liquid dishwashing detergent • source of grease (such as oil) Procedure 1 Design an experiment that will answer one of the following questions. • Can sugar and copper sulfate both dissolve in the same container of water? • Is the$:$BX9YCoRIwO07zTilEpNzxDqUZ82DmTsgB6LeqUqyRTsLLe7dXanuFgOENQR/cKOA19FN9FOq1yRK
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2vsHsgRDIij7CFNOZBQ/xFXSwr7ae8TlkyM=$:$ts such as nails or washers • bucket of water or hose Do this… 1 The small metal objects are your ‘gold’. Mix them up with the soil and put the mixture in the bowl. 2 Half fill the bowl with water. science fun 3 Hold the bowl with a hand on each side. Move the bowl around in a circular motion to swirl the water through the soil. The soil should start lifting up into the water. 4 Let the water wash over the sides of the bowl as you move it around. The aim is to wash some of the soil out of the bowl with the water. 5 Keep adding water and swirling the soil around so it is gradually removed from the bowl. You should see the ‘gold’ collecting on the bottom of the bowl. 6 See how pure you can get the ‘gold’. You may have to practise to improve your technique. Record this… Describe what happened. Explain why you think this happened. 148 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>165</Page_no><display_no>149</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Magnetic separation Your recycle bin at home contains a mixture of insoluble solids. It probably contains steel cans, glass jars, aluminium cans, paper, cardboard, plastic bottles and packaging. After collection, this mixture needs to be separated so that the different substances can be recycled and then re-used. Magnets are a convenient way of separating any rubbish made of iron or steel. Iron is always attracted to magnets. As steel is more than 95% iron, it too is attracted to magnets. Magnets also attract the metals nickel and cobalt, but do not attract other metals such as aluminium, copper or gold or substances such as plastic, paper or glass. Magnetic attraction allows iron and steel to be easily removed $:$9JGAPiqwRYcc1e48I7YSvRheR05jugIQL+bMaqyPMxIx9vIgsafHFXpkU0XQDXCjmSWEoIVR2u2N
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cAJTSW6Wq9o9i3TFcTyX5h6V9rbWwdeau/2IYFbSQbB6w1AW$:$e metals are also magnetic. This allows another magnet to pull normally non- magnetic metal items such as aluminium cans and bottle tops out of the rubbish. Gravity separation Not all mixtures contain a collection of solids like those in your recycle bin. Many mixtures are suspensions which contain insoluble solids dispersed through a liquid. Gravity separation uses gravity to separate heavier substances from a suspension. The heavier particles sink to the bottom of the container. Gold panning (shown in Figure 4.2.2) uses gravity separation. The heavy gold particles drop to the bottom of the pan, allowing the lighter mud and water to be poured off. Unit 7.3 Panning for gold uses gravity separation.Figure 4.2.2 Decantation is a type of gravity separation that lets suspensions of solids or liquids separate naturally. The top layer can then be poured or scraped off. The top layer could be a: • liquid, such as oil • solid, such as plant material like leaves and twigs in soil • liquid, if a heavy solid has settled to the bottom. Decanting is used in a kitchen to pour off cooking water from vegetables in a saucepan. Sometimes sediment will collect at the bottom of a bottle of wine that has been left to stand. Pouring the bottle into a glass container (a decanter) leaves the sediment in the bottle. Decanting is used in many industries. Figure 4.2.3 on page 150 shows one method used in science laboratories. Mixtures 149 ]]></TextData></Page><Page><Page_no>166</Page_no><display_no>150</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[decanted liquid sediment Sieving A sieve is a barrier with holes in it. Small solid particles can get through, but large ones cannot. The process is called sieving. A colander is a sieve that is used in the kitchen to strain water from food. Likewise, large lumps in flour can be removed before baking by sifting the flour through a strainer, or f$:$BzodxXFFO7WTkYiAD/p99i7PY/2U3FyqZQf64hz1NrIntXe4bmTeZFMV0OZTQWD/RTdH7svDfIZw
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Eau9UpI=$:$od supply passes through your kidneys in about 1 hour. This means your blood has passed through your kidneys about 24 times in a day. From this you make about 1 litre of urine. Filtration Filtration, also known as filtering, is a widely used method of separating: • solids from gases • solids from liquids • liquids from gases • liquids from other liquids. Filtration uses a filter. A filter is like a sieve in that it is a barrier with many, many small holes (often microscopic in size) in it. These holes are smaller than the particles being separated and so these particles get caught in the filter. However, smaller particles pass straight through. Many filters are a mesh of fine fibres like cotton wool. Others include rock with fine pores (small holes) in it. Filters are used to separate coffee grounds from filter coffee. Likewise, tea bags are a type of filter that allows water to move through them while keeping the tea leaves in the bag. The face mask shown in Figure 4.2.5 is a filter that separates dust from air. A similar filter is used in most vacuum cleaners. The filtered, clean air is then blown back into the room. Filters can also be found in air conditioners, washing machines, dryers, swimming pools, car engines, fuel systems and air cleaners. Filters are also used in the laboratory. Several different methods are used, but the most common uses filter paper. People working in dirty or dusty environments stop dust from entering their airways by wearing face masks. Figure 4.2.5 4.3 150 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>167</Page_no><display_no>151</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Centrifuging A simple centrifuge is shown in Figure 4.2.9. It has chambers that are spun very fast around a shaft. Any tiny particles suspended in the liquid are forced to the sides and then to the bottom of each chamber. Folding a filter paper There are two methods to fold filter paper. The method you choose depends on the material you are filtering. The conical fold is shown in Figure 4.2.6. Open out. How to make a conical fold for filter paper The other method of folding is called fluting. This is shown in Figure 4.2.7. Open out. Fold each section in two, alternately folding up and down. end on Open out. Two folds will be the ‘wrong’ way, but it will work. You could bend both these sections inwards in the centre. How to fold a fluted filter paper Fluting increases the amount of surface in contact with the liquid and increases the filtration rate. It is useful for very fine suspensions that can block many of the holes in the paper. Figure 4.2.6 Figure 4.2.7 How to filter To filter, set up the equipment as shown in$:$EtPDXKYyfCyuJtDbQA+trQoEUdvXq9PDRKJrGWf58tvf03FNRD1lA7ysbP0go+CHxFXuBlHUfxV2
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kQ==$:$stand and clamp Figure 4.2.8 Prac1 p. 155 Prac2 p. 156 A simple centrifuge is used to separate substances in the laboratory. Figure 4.2.9 Mixtures 151 ]]></TextData></Page><Page><Page_no>168</Page_no><display_no>152</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[A common use of a centrifuge is in the spin cycle on a washing machine, in which the clothes are spun very fast in the bowl. Figure 4.2.10 shows how this works. Water is forced out of the clothes and through the holes in the bowl. It then drains away and is pumped out of the machine. In a similar way, salad spinners are used in the kitchen to dry washed lettuce. There are many other designs for centrifuges. Some very complicated ones are used in mining. Centrifuging is also widely used in laboratories. Centrifuging blood Blood transfusions are often needed to replace blood lost in serious accidents and during major surgery. However, somet$:$lB2dWJcFS5M3mR3vOOc5td0RiQKOf3A3TfuSb7d+KIbmCO/LDy+xWNMWEuUPdMVYV/zz2mUbeHIF
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VhIxvjZI/D74nNYGsbp8ixuI3zd3EDZHWFj4ixo0I4QN7XCT5Psn69ZwBPBcaCXi$:$o treat people who have haemophilia. Patients with this disease can bleed to death because their blood does not clot to seal a cut. water forced out through small holes wet clothes spin to basin spinner A washing machine spin cycle acts as a simple centrifuge. Figure 4.2.10 Patients with anaemia have insufficient red blood cells in their blood. They can be given whole unseparated blood but this can stress their heart if they also have heart problems. Instead, they are given transfusions of red blood cells because these place less stress on the heart. Blood is being collected from these blood donors. In Australia many people donate their blood to the Red Cross Blood Bank to save the lives of others. Figure 4.2.11 Blood that has been centrifuged separates out into layers. Figure 4.2.12 plasma red blood cells 152 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>169</Page_no><display_no>153</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review Remembering 1 List examples of sieving and filtering around your home. 2 Name an example of centrifuging th$:$48Jp5rCf6D1ccGQBkxKXc109rA3K+dv18XaJiArTFWnkwsQAXLjy4uWp6qPCTX1y081dpOyz4JgB
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Kh0Q6BWKr/wApE+79Vm48XK3XAX9pDaWz5n9H4XL6IPMQWft1l0=$:$hows how to set up equipment for filtration. Applying 9 Identify a method of separation that could be used for the following situations. a You want some fine clean sand without any sticks or stones from the soil in your garden. b You drop some nails into the sand in your backyard. c You drop some hundreds-and-thousands into the flour your mum is using for a cake. d The gravel border along the driveway at home has become covered by bark, and leaves and fine sticks are mixed with the gravel. e Your tea bag breaks in your cup of tea. Analysing 10 Compare gravity separation and centrifugation by listing their similarities and differences. 11 Compare filtering and sieving. 12 Compare the two different methods of folding filter paper by listing the advantages and disadvantages of each. 13 Car air cleaners are structured as shown in Figure 4.2.13. Figure 4.2.13 a Compare the structure of the air cleaner with that of a fluted filter paper. b Describe why this design is effective as an air cleaner. Evaluating CCT 14 When car tyres are replaced, the installer attaches small weights to the wheel rim to check that the wheel is balanced, with an even mass distribution all around. This is because anything that spins fast and is unbalanced can put an enormous stress on the shaft it is attached to. Propose how this could apply to a centrifuge if it was not used properly and was unbalanced. 15 Propose a reason why vehicle air, fuel and oil filters need to be changed regularly. 16 You are fixing your skateboard and accidentally drop a steel wheel nut into a drain that is too deep to put your arm in. Propose a method of recovering the nut from the drain. 4.2 Mixtures 153 ]]></TextData></Page><Page><Page_no>170</Page_no><display_no>154</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review4.2 17 Some washing machines do some test spins before starting the spin-dry cycle. After doing this, the machine may not spin the clothes but instead agitate them back and forth for a while, before trying another test spin. Propose a reason why the machine has been designed to do this. Creating CCT 18 In the laboratory, you are given a mixture of sugar, sand and gravel. Design a way of separating these three substances. 19 Construct a table in which you: a list each of the five methods of separation in this unit b describe how each method works c specify an exampl$:$ymGrZjwiBTgbxaC3auaqVeCGHQEX/0rNBP8ILXt1cDljLAB4zkoMPtPZ/CEb09xYnqIw12jFFbUa
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gbu9os1JXWPt$:$es relevant photographs. 3 Research a method of cleaning up oil spills in the ocean. Such methods could include the use of sorbents, separating devices, dispersants or skimming. Figure 4.2.14 shows one method of cleaning up an oil spill. Present your findings in digital form in which you briefly outline the procedure for the method you have chosen to research, and how the method works. ICT ICT ICT Cleaning up ocean oil spills can be achieved by several methods. This string of polystyrene floats (called a boom) has trapped oil floating on the ocean’s surface. Figure 4.2.14 Prac3 p. 156 154 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>171</Page_no><display_no>155</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations Purpose To compare conical and fluted filter papers. Hypothesis Which filters better—a conical filter paper or a fluted filter paper? Before you go any further with this investigation, write a hypothesis in your workbook. Materials • 1 spatula sand • 1 spatula copper carbonate (CuCO3 ) • 1 spatula • 2 funnels • 4 filter papers • 4 × 100 mL beakers • 2 stirring rods • 2 stopwatches or timers • retort stand, bosshead and clamp or filter stand Procedure 1 Place two funnels in the clamp or filter stand. Place a beaker under each funnel to collect the filtra$:$oJ0PTvtEdXoJyaNMhw6MP3B9+ha08Plvvhxpz7dG5rIW0Sz+KmhvRfWM6HeKlRdWiW9guZGoMUqY
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ssWKegCqRseuraXU4Tkz$:$ the fluted filter. 6 Add more of the sand and water mixture to each filter paper until all of the liquid has been filtered. Stop the timer when the filter stops filtering. Leave any remaining sand in the beaker. Note the time taken for each filter, and how clear the filtrate is. 7 Repeat steps 1–6 with new filter papers, but this time use copper carbonate instead of sand. Results 1 Record the appearance of the filtrate, for both the sand and the copper carbonate. 2 Record the time it took for all of the liquid to pass through each filter. Practical review 1 Compare the rate at which the two differently folded filter papers filtered each of the mixtures. 2 Construct a conclusion for your investigation. 3 Assess whether your hypothesis was supported or not. 4 Propose a reason why one folding method was better than the other. conical filter paper fluted filter paper Figure 4.2.15 Safety Copper carbonate is toxic so do not touch, sniff or taste it. Comparing filters1 4.2 Mixtures 155 ]]></TextData></Page><Page><Page_no>172</Page_no><display_no>156</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations4.2 STUDENT DESIGN STUDENT DESIGN Separating solids Purpose To separate a mixture of sand, salt and iron filings. Materials • 1 spatula sand • 1 spatula salt • 1 spatula iron filings • 100 mL beaker • 3 spatulas • magnet (wrapped in plastic) • a choice of equipment such as filter paper, funnels, extra beakers Procedure 1 Use different spatulas to measure out one spatula each of sand, iron filings and salt into a beaker. Use one of the spatulas to mix the three solids together well. 2 Design a method to separate these three solids from each other. 3 Write your procedure in your workbook. 4 Before you start any practical work, assess your procedure. List any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required mate$:$1BRyPytbmIIDc+l5VwfIYgME0vm4R6oNnCBWuA0nVqx0nbl28B93qPeJcDzp8T9JzobzeJE67i0E
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1qvh8QDpvr5AhW9JuKG32lBMM/dsD8XNMwhS8baWiNDcXIK26VxA1w4vS6fq$:$tigation, write a hypothesis in your workbook. Materials • 50 mL cooking oil • detergent (for cleaning up) • equal masses of cotton balls, paper towel and kitchen sponge • 3 plastic cups • 2 wide-mouth jars • tweezers • access to timer Procedure 1 Carefully read the list of materials provided. 2 Design a method that will allow you to compare how well cotton balls, paper towel and a kitchen sponge absorb cooking oil that has been mixed with water. 3 Write your procedure in your workbook. 4 Before you start any practical work, assess your procedure. List any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required materials and start work. Practical review 1 Construct a conclusion for your investigation. 2 Assess whether your hypothesis was supported or not. 3 Construct a report using the headings listed in Unit 1.4. Unit 1.4 3 SafETy A Risk Assessment is required for this investigation. 156 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>173</Page_no><display_no>157</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The soluble substances in a solution are far too small to settle or be trapped in filter papers. Different methods are therefore needed to separate them from the solvent they are dissolved in. In the photo a separation method called distillation is being used to make perfume from rose petals. Separating soluble substances4.3 Separating colours Are inks in marker pens and food colours made of just one pure substance? Collect this… • water • food colouring (green is good) • marker pen • sheet of newspaper • pair of scissors • 4 narrow drinking glasses • sticky-tape or Blu Tack • four pencils (hexagonal cross-section is better than round) or icy-pole sticks Do this… 1 Cut four blank strips $:$389xUTAUClZgyuwNLtts80e39zn9V5usbw/FcIgOoqoiiGFtVM0ffnCsYhC8izExpYHw1JH5DL7J
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bkqO6rm/9x3cjfEMIrFG6qz1F8dS1Dy/YCLLSP4YukoiCTHcqEnV6sKIKoBVyDastuZL$:$ up the paper as shown. It is best to put the water in first. The water level must be below the coloured line on the paper. 4 When the water has almost reached the top of each strip, take the strips out and let them dry. Record this… Describe what happened. Explain why you think this happened. Mixtures 157 ]]></TextData></Page><Page><Page_no>174</Page_no><display_no>158</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Chromatography Chromatography is a process that can separate a mixture by making it move through another substance such as a gel, column of liquid or strip of paper, as shown in Figure 4.3.1. Here, water is the solvent. It dissolves the dyes from ink or food dyes and carries the colours with it as it moves up the paper. Chromatography works because different chemicals in mixtures are attracted to the paper by different amounts. Substances that are strongly attracted to the paper are harder for the solvent to move along. These substances do not move very far. Weakly attracted substances move the furthest. Chromatography is very important in industry. It is used to find out what is in oil and gas, and to identify pollutants. Chromatography is also used by pharmaceutical manufacturers to analyse plants and animals for possible useful medical drugs and to test the quality of their products. Environmental scientists use chromatography to identify chemical pollutants. science fun Candy crystals Can you grow big candy crystals? Collect this… • sugar (sucrose) • water • food colouring (optional) • flavouring (optional) • clean glass jar • clean cotton or string • pencil or icy-pole stick • metal saucepan • stove Do this… 1 Pour 3 cups of sugar and 1 cup of water into the saucepan. 2 Heat, stirring constantly, until all the sugar has dissolved. Try not to boil the solution. A few drops of food colouring and ½ teaspoon of flavouring can be added, but this may slow your crystal formation. 3 Cool the sugar syrup in the refrigerator until it is at about room temperature. 4 Soak the string in the syrup and then hang it to dry in the air. 5 Set up yo$:$LRnPoZdvbMHlHZm+uBSvqKUaJ0xs7vkqq+/5y3vOzbMIM9QV4N8N1O7VdpnPhSqmvVaXyWAHzU0F
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GM/4yvjvHC87eEVKAq0snvKfL0WfmGNoPqYf7CMEq14jvHeO0tU=$:$h a particular pen, then chromatography can be used to identify the ink you used and match it to your pen. 158 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>175</Page_no><display_no>159</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Evaporation Evaporation is the change of state that occurs when heat causes a liquid to change into a gas. It is a natural process that dries up pools of water on the road and clothes on a line. Water boils at 100°C but it does not need to be 100°C for water to evaporate. Water evaporates at all temperatures above 0°C, meaning that wet clothes will dry at any temperature above 0°C. However, evaporation speeds up at higher temperatures. This ex$:$NTjY+SmysAQuyudkSYn+uHw1S8bAirAMWJ7oboGUMK8IBCGGLTP62IBPeKjw+sNxvsPiKGky+9qa
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s1vj6IPMQWft1l0=$:$e distillate that drips into the flask will be very pure because the solutes do not evaporate and pass into the condenser. This liquid is known as the distillate. The Bunsen burner boils the solvent so that it evaporates very quickly. Distillation is able to separate several liquids from each other if they have different boiling points. For example, alcohol has a boiling point of 78°C while water boils at 100°C. These two liquids can therefore be separated by distillation. All of the alcohol will evaporate from the mixture first (at 78°C), leaving the water behind. The water will then evaporate off at 100°C, leaving behind whatever solute was dissolved in it. As well as separating solutions in laboratories, distillation is used in: • producing alcoholic drinks such as vodka and bourbon • separating crude oil into petrol, diesel, lubricating oils and other components • removing impurities from drinking water • separating oxygen, nitrogen and argon from air for industrial use • perfume manufacture. 4.5 4.6Prac2 p.164 160 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>177</Page_no><display_no>161</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review Remembering 1 Recall methods of separating mixtures by matching each method with its correct description. Choose from A, B or C. a chromatography b evaporation c distillation A A process using evaporation and condensation to separate and recover both solute and solvent B A process that can separate a mixture by making it move through another substance like a paper strip C A process in which heat changes a liquid into a gas, allowing recovery of the solute but not the solvent 2 From the examples in this unit, name the separation process used to: a separate different coloured substances from food colouring or ink b collect salt crystals from seawater c make alcoholic drinks like gin and whisky. Understanding 3 Explain the process by which chromatography can separate substances. 4 Explain the process by which distillation can separate a solute and a solvent and allow you to recover both substances. 5 You are making copper sulfate crystals in the laboratory by evaporating water from a solution of copper sulfate. Describe how you could: a make the crystals rapidly b form larger crystals by evaporating the water slowly. 6 Draw a diagram that shows how crystallisation stops impurities from beco$:$Yo1caEzEViFSHHMLArt5iVqyEIRzWK2tf7UJgtXRJQtDr4AvcEM6/cpAaop4y/FnMmzfbkwMSfx/
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hZc7vg==$:$ation. larger rock larger rock small rock vegetation plastic sheet Figure 4.3.7 10 Compare evaporation of water and boiling of water. 11 Two identical solutions are allowed to evaporate. One evaporates slowly. The other evaporates quickly. Compare the size of crystals formed from each solution. Evaluating CCT 12 A whisky maker wants to reduce the amount of water in a mixture to give a higher concentration of alcohol. Justify the choice of distillation rather than evaporation as a separation method. Note that alcohol boils at 78°C and water boils at 100°C. 13 When you dry your bathers after swimming in the sea, they are crisp with salt. However, if you rinse them in fresh water first, they dry clean and salt-free. Propose why the two methods of drying produce such different results. 4.3 Mixtures 161 ]]></TextData></Page><Page><Page_no>178</Page_no><display_no>162</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review4.3 14 Candy crystals are formed in the science4fun on page 158. a Identify the process that allows these crystals to form. b Propose a way of making even larger candy crystals. 15 a Outline why impurities tend not to join with crystals formed through evaporation. b Pure crystals are often left behind once all the solvent has evaporated. Impurities are left behind too. Propose a way of separating these impurities from the pure crystals. Creating CCT 16 Construct a card game of nine cards in which each card describes a different method of separation. • Use no more than five lines. • Do not use diagrams. • Do not use the name of the method of separation or similar words. • Write the separation method on the back so that someone else can check what it was later. Inquiring 1 Research how: • salt is collected from commercial salt pans • liquid nitrogen or liquid oxygen is made • crude oil is cracked using fractional distillation. Present your fin$:$V6KxATyHADu1B/pbe8MFGQx8Rl70cwQlhrn0Cr6zR6/KshLlDPwZ+BCj5GSGmAezI9pN264gjkQ0
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JJ369p9v6C0RJkMR5fc7V4/fdNK6bf/XEAKk0fKaZg==$:$to stop them getting too smelly. These innersoles use a process called adsorption to remove soluble substances that cause smell from the sweat that builds up in shoes. Research adsorption to find: • how adsorption works • what activated carbon is (Figure 4.3.8) • how charcoal tablets are used to control ‘traveller’s diarrhoea’ • other examples of how adsorption is used to separate substances. Present your research in digital form with photographs and diagrams. ICT activated carbonfilter disc particle filter filter case This face mask has a carbon filter for adsorbing poisonous gases. Figure 4.3.8 162 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>179</Page_no><display_no>163</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations Purpose To grow copper sulfate crystals and compare their sizes when formed by fast and by slow evaporation. Hypothesis Which do you think will prod$:$Jz/kaDGL8xr0EJdXY297YYGI+vsClsOxtZCg6/b0amnME76lqI72X+n+JjVpPxeFC3PP1o428hsJ
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zUZkgYcwMcZHS+cFoX3mfZw=$:$ (such as 250 mL beakers) Safety A Risk Assessment is required for this investigation. Do not eat or taste the Smarties or M&Ms. Procedure 1 Design an experiment that will use chromatography to separate the colours that make up the candy shell of a Smartie or an M&M. Figure 4.3.10 might give you some ideas. 2 Write your procedure in your workbook. 3 Before you start any practical work, assess your procedure. List any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required materials and start work. Hints In your experiment: • use water as a solvent • raise the filter paper on something (such as a beaker). Results Record what you saw. Practical review 1 Construct a conclusion for your investigation. 2 Assess whether your hypothesis was supported or not. A forensic scientist inspects the pigments used in different black industrial dyes. A drop of dye was placed in the centre of a piece of filter paper and chromatography separated its colours to form rings. Figure 4.3.10 Chromatography investigations2 164 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>181</Page_no><display_no>165</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Water is vital for life. Drought in much of Australia has forced us to conserve water as never before, and explore new ways of obtaining water to drink, cook with and shower in. Traditionally water has come from rivers and dams, but increasingly we are turning to groundwater and new technologi$:$Iw922ozWT7u8spESE637W8iSpS9xoh1f1zO9z8Dx/J3KoBWNUbNhw9zS7z6DSZw4EQzEH7/dikKe
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AQ3frYdSaJ8JoH26JtuVd3FPgZnVijbykMqKWq3Z$:$dissolved in a liquid Oxygen gas dissolved in blood Detergent dissolved in water D Gas dissolved in another gas Oxygen gas dissolved in nitrogen gas Water vapour dissolved in the air Q4 Sand is a mixture of small rock fragments, minerals and the remains of living things. The following table shows some of the substances in a sample of sand and their characteristics. Magnetic Weight Fragment size Silica No Not heavy Large Coral and shell fragments No Not heavy Large Feldspar No Not heavy Small Magnetite Yes Very heavy Small Rutile No Very heavy Small Select the correct techniques and the order that would allow rutile to be separated from all other substances. A Sieving then gravity separation B Gravity separation then magnetic separation C Gravity separation then sieving D Sieving then magnetic separation CCT CCT Mixtures 177 ]]></TextData></Page><Page><Page_no>194</Page_no><display_no>178</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit 4.1 L Aqueous solution: solution that has water as its solvent Concentrated: there is a lot of solute in the solvent Dilute: when there is little solute in the solution Disperse: when particles spread without dissolving Dissolve: break up into tiny particles that are smaller than the eye can see Insoluble: substance that does not dissolve in a particular solvent Mixture: a substance made from two or more pure substances that have been stirred together and that can be separated to recover the original chemicals Saturated: as much substance as possible is dissolved in a solvent Soluble: able to be dissolved Solute: a substance that dissolves to make a solution when we mix it into another substance Solution: when a substance dissolves in another, forming a clear mixture Solvent: a substance that dissolves another substance Suspension: mixture in which a substance will not dissolve in another and quickly separates out if left to stand Unit 4.2 L Centrifuge: device that spins very fast to separate solids from liquids, or liquids from other liquids Decantation: separation by pouring liquid off the top of a mixture of solid in liquid, or liquid in liquid Concentrated Dissolve Decantation Glossary Filter: screen or membrane used in filtration Filtrate: liquid that passes through the filter paper Filtration: separation of solids or liquids from a liquid or gas by using a barrier with holes smaller than the particles being separated Gravity separation: a method of separating two components from a suspension by using the force of gravity to separate heavier particles to the bottom Residue: solid left in the filter paper after filtration Unit 4.3 L Chromatography: a method of separating a mixture by making it move over or through another substance that stays still Crystallisation: formation of crystals as a dissolved substance solidifies Distilla$:$h/sbYy99UHwnViWiUbU7PrXjzptkxV2ieH501qfPWueNPA9WEqhyMe58NSIT0Kt/Pdm5PaYCDE9O
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TRgiHBBbEFsQRZ/BXA==$:$tography 178 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>195</Page_no><display_no>179</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[SCIENCE TAKES YOU PLACES Look who is using science TAXONOMIST My name is Dr Will White and I am a fish taxonomist with the CSIRO Marine and Atmospheric Research laboratories. I work on applied taxonomy and biogeography of Indo- Pacific fishes, mostly sharks and rays. A large proportion of my work has involved field trips to Indonesia to look at the fisheries over there and I have discovered a large number of new species of sharks and rays during this work. I have been involved in the description of almost 50 new species of sharks and rays. I always had an interest in sharks and rays and have always enjoyed diving and underwater photography. Science has been a great way not only to learn new things but also to lead a varied work life with a large amount of travel. SEWAGE QUALITY ENGINEER My name is Brett Maurer and I am a sewage quality engineer working for City West Water. Trade waste (waste released into the sewers from industry) can potentially contaminate and damage pipes and sewage treatment plants. It can also put our sewer workers at risk, particularly if it is releasing dangerous gases. I take samples of sewage and test them to determine what contaminants they contain and whether they meet the regulations for discharging into the sewer. I also collect samples from the space in the pipe above the flowing sewage to determine what gases are there. The information obtained also helps our business identify ways of treating and recycling industrial water and using biosolids—the nutrient-rich sludge that is generated from the treatment plant process. Water is essential for living and my work helps to ensure that supply meets the increas$:$ugj1mdYP+SBujt8RUEABBexbiJt8U+fOoMfdQjbh47OWhzbv09Kl59Ut/KbjPqrhPKajS3jh/S7G
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2ZgQn2OCfu52mZ3DW4C2pq3Gc+iDzEFn7dZd$:$ influenced the development of agricultural practices S L ADDITIONAL • debate why society should support biological research CCT EU • research the contributions of Australian scientists to the study of human impact on environments. S WE PSC After completing this chapter students should be able to: Have you ever wondered... • why there are different types of plants and animals? • why different organisms live in different places? • how human actions affect other living things? 180 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>197</Page_no><display_no>181</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[5.1 Some living th$:$rTweHdf5J78FXdLmqGFarlQMUytVGhZLmZk/AWj6or6j8LuJQEayNKnZyBr6nj/3WavsW6sP0ZBC
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79Um$:$address. For example, your habitat includes your home, school and perhaps your sporting club. Habitats are very varied. Figure 5.1.1 shows a wetland— one example of a natural habitat. Every living thing has particular needs, and will live only where these needs are met by the resources available in the habitat. Some of the resources a habitat must provide for an organism to survive and reproduce include: • food • water • shelter and living space • a suitable temperature • mating partners for reproduction • gases such as oxygen. The place where an organism lives is its habitat. This wetland will be the habitat for many different organisms. Figure 5.1.1 For example, all the needs of the crocodile in Figure 5.1.2 on page 182 are met by the resources in the river and the surrounding river banks. Habitats and interactions 181 ]]></TextData></Page><Page><Page_no>198</Page_no><display_no>182</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Freshwater crocodile distribution WA NT SA QLD NSW VIC TAS ACT The Australian freshwater crocodile is foun$:$NEpDS6am38mZtgHjP2rx4cVUuDCDf2fcG2n3SdoqLX7BQm2hY7KzGfKcPH+Bi+MhgS/j1bWIMyKm
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0ToKOgC7GV/zfqe3ogAIKlnDRYcB78abp+oFXiVABBjog8xBZ+3WXQ==$:$clude light, wind, soil, air and temperature. The number of organisms of the same type, living in the same habitat, will vary over time depending on the availability of food, water, living space and mating partners. 5.1Prac1 p. 189 Adaptations To survive in their habitat, organisms have adaptations. Adaptations are characteristics that assist organisms to survive and reproduce. Adaptations help organisms to get food and water, protect themselves, build homes and reproduce. The position of the eyes and nostrils of a crocodile are adaptations. They allow the crocodile to breathe air and look for prey when the crocodile is almost totally submerged in the water. The spotted-tail quoll shown in Figure 5.1.3 is a marsupial that lives in the wet and dry forests of eastern Australia, from Queensland through NSW to Tasmania. The quoll’s colouring means that it is well camouflaged. This allows it to sleep in hollow trees and rock crevices without being seen by other animals that would hunt it for food. A quoll uses its sharp claws and teeth to catch rats, birds and reptiles but will also eat dead remains. Quolls are nocturnal, which means they are active and hunt at night. A quoll can see in dim light. The spotted-tail quoll is the largest meat-eating marsupial on Australia’s mainland. Figure 5.1.3 182 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>199</Page_no><display_no>183</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Native trees growing in parts of Australia need to survive frequent fires. Some trees like eucalypts (gum trees) have buds buried deep within the trunk where they are protected from the heat of the fire. Normally these buds do not sprout. However, if a fire destroys most of the leaves on the tree, these buds grow and quickly cover the tree with new leaves. You can see this in Figure 5.1.4. All plants need light if they are to survive. Plant$:$Kg3RwnIui7dcIa4DMK/136O0QuGf15pqTM8PwI1M98EoujBV3z7p04Ibl2Ol+Hx4z7l/vdrVO+kc
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B4t8uUBZMK57BcXMP+capQ2+1JBQ/sxpCYv/Rt1RUwH+cLbvlsVR8+iDzEFn7dZd$:$phere is made up of many ecosystems such as forests, wetlands or the coral reef shown in Figure 5.1.8. An ecosystem is a system formed by organisms interacting with each other and their non-living surroundings in a balanced way. In an ecosystem there are many habitats. The relationship between the biosphere, ecosystems and habitats is demonstrated in Figure 5.1.9. A coral reef is a complex ecosystem with many different types of animals living together. Figure 5.1.8 Epiphytes Epiphytes are plants that grow on other plants. Epiphytes use host plants for support, but take nothing else from them. The epiphyte and the host plant are both able to make their own food; therefore an epiphyte is not a parasite. Common epiphytes are bird’s nest ferns and staghorn ferns and some types of orchids. Biosphere Forest ecosystem Desert ecosystem Ocean ecosystem Industrial habitat City ecosystem Suburban garden habitat Reef habitat The relationship between the biosphere, ecosystems and habitats. In the biosphere there are many ecosystems. In an ecosystem there are many habitats. Figure 5.1.9 Habitats and interactions 185 ]]></TextData></Page><Page><Page_no>202</Page_no><display_no>186</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The organisms in an ecosystem are interdependent. Interdependent organisms depend on each other for survival. There are three main types of interdependence or symbiosis. 1 Commensalism: An example is the cattle egret (Figure 5.1.10) hunting for food in fields among cattle or other livestock such as horses. As the cattle graze they move and in doing so stir up insects living in the grass. Cattle egrets follow the grazing cattle and feed on the insects that are disturbed. The egrets benefit from this relationship because the cattle have helped them find food. The cattle are unaffected by the egrets. 2 Mutualism: This is an interaction where both t$:$+b94sgDaiW4fbCoWUKyEmkDxvToiYd6F5c9dkR2XjIPAmW8S11gBZm7am3GKqYoJ6VOY3KplFdqj
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8gWn+EBsU5BYThoaSYEU$:$ organism (the parasite) lives on or in another type of organism (the host). The parasite obtains food and shelter from its host, but often harms or may even kill the host in return. Heartworm is a parasite that lives in the hearts of dogs. The worms breed rapidly and when present in large numbers can clog up the dog’s heart. The worm uses the dog for shelter and food, but in the end the dog often dies. Figure 5.1.12 shows a dog’s heart with a major infection of heartworm. Heartworm can be prevented by giving the dog a tablet regularly or an annual injection. Heartworms infecting the heart of a dog. This heartworm is microscopic. However, adult female heartworms can grow to between 25 cm and 35 cm in length. Heartworms are parasites that can eventually kill their host. Figure 5.1.12 Lichen growing on a rock. The algae and fungus that make up lichen need each other. Figure 5.1.11 186 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>203</Page_no><display_no>187</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review5.1 Remembering 1 State an alternative name for a living thing. L 2 List the important things a habitat must provide so that organisms will be able to live there. 3 List the adaptations that help the following Australian animals catch their prey: a crocodile b spotted-tail quoll. Understanding 4 Define the term habitat. L 5 Clarify what an adaptation is. 6 Explain why some organisms are found over a very wide area, whereas others live in very restricted areas. 7 Describe possible causes of a change in the number and type of organisms living in an area. 8 Outline what scientists mean when they say that organisms are interdependent. L 9 The mountain pygmy-possum hibernates under thick snow during winter. Explain how each of the following adaptations would assist the possum to hibernate. a The mountain pygmy-possum has thick fur. b It stores fat from food eaten in summer. c Its metabolism (body functions) can be slowed until they nearly stop. Applying 10 Use examples to describe two types of symbiosis. 11 Identify adaptations that allow: a eucalypts to survive bushfire b Smilax to reach sunlight. Analysing 12 Contrast biotic and abiotic factors. 13 Compare the biosphere and an ecosystem. 14 Classify the following as commensalism, mutualism or parasitism. Give reasons for your answers that include a description of the benefi$:$T2YMkTmogzBMroaD7U3Dzt7SDPBIgWGzobI2R/rqSHyh824d8CCcqbtjZCUz2UKkEmvZpkKic1KL
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2cB8FM85T+iDzEFn7dZd$:$nment. 20 Construct a poster or digital presentation outlining the features of commensalism, mutualism and parasitism. Include at least two new examples of each. 21 Work in a small group to design a coastal rockpool ecosystem. Attach a concept map showing how the organisms in the rockpool interact. Inquiring 1 Research an Australian native animal. It could be a marsupial, bird, reptile, fish or some other marine creature. Whichever animal you choose, find: • its common and biological names • a map showing its distribution across Australia • images or video of it and the typical habitat it lives in • the biotic factors that affect its habitat (such as plants and other animals) • abiotic factors that affect its habitat (such temperature and rainfall) • the adaptations that help this animal to survive and reproduce successfully in its habitat. Present your findings as a poster or PowerPoint presentation. ICT 2 Parasites can affect the health of humans. Research parasites and find: • an example of a human parasite • how humans become infected with a parasite • the symptoms the parasite causes and the long-term effects on health. Present your findings as a poster or PowerPoint presentation. ICT ICT 188 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>205</Page_no><display_no>189</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations5.1 What lives in your schoolyard? Purpose To investigate the small organisms that are living in various habitats of the school grounds. Materials • small paintbrush • protective gloves • magnifying glass • sweep net • 4m of string • 4small masses (such as stones) • f$:$PUMwrIEtwSp85pEf3cmfXoxSze4n785BJDkChqVtWHNkB42jllMOAuPbY2xD16Tmy5KIDKyhqVcI
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CQygQQ56E96Cl1Y=$:$g halfway up to make sure that the organisms do not escape. 6 While another student holds the zip-lock bag, place the net over it, loosen your hold and turn it inside out into the bag. Carefully shake and remove the net from the bag, being sure to seal the bag so that the organisms do not escape. 1 SAfeTy Stinging insects might be captured, so gloves should be worn by the person who has to hold the net and shake the organisms into the plastic bag. If any are still caught in the net, avoid contact. Use a paintbrush to remove them. 7 Observe the organisms through the zip-lock bag and try to identify them using your field guide. Count the numbers of each type of organism. 8 Release any organisms that you have found. Results 1 Record the time and date of your experiment and describe the area in which you made your observations. 2 Construct a table showing the appearance and number of each type of organism at your site. 3 Record your results along with those of other members of your class on your map of the school grounds. 4 As a class, prepare a poster of what lives in the school grounds. Practical review 1 Compare the numbers and different types of organisms caught at the various sites. 2 Identify the site that was the most successful in terms of the: a number of organisms caught b variety of organisms caught. 3 Discuss the differences between the sites that could cause these variations. 4 Identify any other factors that could have led to this result. 5 Classify the organisms into groups according to the environmental conditions each preferred. Examples include dry or moist long grass or short grass, sun or shade. 6 a Discuss whether or not you would expect the same organisms in your sweep if you conducted this experiment at: i different times of the day ii other times during the year. b Propose reasons for any variation. c Describe a way of testing your predictions. Habitats and interactions 189 ]]></TextData></Page><Page><Page_no>206</Page_no><display_no>190</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations5.1 Looking at earthworms Purpose To investigate how worms behave in their habitat. Materials • trowel • gloves • containers • stereomicroscope or magnifying glass • sheet of white paper or a white tile Procedure 1 Dig for worms in the garde$:$gk4l5R3R29eLBfZ7TWzJ9sphq2Y8IgU4OWL1oMwuT50XlJkgmlNhl6E3hAYrbHiQbf1x8cO0Ofts
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rjP10MH8z5H4ArJ5NRc4nH6eHDxIaQeou5CL9lvyjlFc7gaM7Jtdnw==$:$ 7 Run your finger very gently from the back to the front of the worm’s underside. 8 When you have finished, return the earthworm to a natural habitat under some leaves in a moist, shady location. Practical review 1 Describe the shape of the worm and how this helps it move through the soil. 2 a Describe how the shape of the worm changed as it moved. b Explain how the change in shape helps the worm move forwards. c Propose what was happening inside the worm to cause these changes in shape. 3 a Describe what you felt and/or saw on the underside of the worm. b Propose how this feature could help the worm move. c Deduce why it is difficult to pull a worm from its burrow. 4 Worms are well adapted to living underground. Identify the adaptations you observed. 5 Propose reasons why you were required to return the worms to their natural habitat after the practical work. SAfeTy Make sure that you are wearing gloves and that you don’t directly inhale any dust. It is important that the worms are treated with care and are not harmed during your investigation. Take care to look after them and then return them to where you collected them, once you have finished. 190 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>207</Page_no><display_no>191</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Healthy ecosystems usually contain many different habitats and a variety of organisms. The organisms living there interact in different ways. Food is one of the most important needs of all living things. Therefore one of the relationships between organisms is a feeding relationship. Some organisms do the eating. Other organisms are the food. Food chains and food webs5.2 Predators in the garden Can I see predators at work i$:$AbgJlo8Y/kc0hvauFIvSTOxp3qW7sUW2VQp0JzmfbjMSElK8pzMeJKZPqkJMFz7zpxUi7kHnJan8
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I4kCtmvrTdhlWiBKxO8=$:$n as herbivores (Figure 5.2.5). Consumers such as lions, dingoes and kookaburras that eat only other animals are called carnivores. Omnivores are consumers that eat plants and animals. Humans, the bilby and some bears are examples of omnivores. When a plant or animal dies without being eaten, its body is broken down by decomposers. Decomposers are organisms such as bacteria and fungi that are able to get the energy they need as they break down dead matter and waste products. You can see a type of fungus in Figure 5.2.6, helping to break down a dead tree stump. The orange fungus on this tree stump is a decomposer organism. Fungi break down the materials that the tree is made from, returning these materials to the soil. Through this process fungi get the nutrients they need to live and grow. Figure 5.2.6 Koalas are herbivores. They only eat leaves from eucalyptus trees. Figure 5.2.5 Habitats and interactions 193 ]]></TextData></Page><Page><Page_no>210</Page_no><display_no>194</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[In the food chain: grass → grasshopper → kookaburra → bacteria the grass is the producer, the grasshopper is a first- order consumer and the kookaburra is a second-order consumer. In another food chain, a lizard could eat the grasshopper. The lizard could then be eaten by the kookaburra. The new food chain would look like this: grass → grasshopper → lizard → kookaburra → bacteria In this food chain, the lizard is the second-order consumer and the kookaburra is a third-order consumer. Food webs In the pond ecosystem shown in Figure 5.2.7, small fish live in constant danger of being eaten. If they go too close to the surface, birds might catch them. If they move away from the protection of the pond weeds, large fish will catch and eat them. The edge of the pond is also dangerous, because frogs and birds are always alert for an easy meal. 5.4 A pond ecosystem is home to a variety of organisms. Figur$:$cTiFUonj+GvCGh8w4we/YAn9ICn/GRWAnUDtZK0gIPkrtluVfUfAgjM8OuSZOfz5MrOvNKBzIzxP
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YCombnPEZqJ9C1UIz3s=$:$ food chains together produces a food web. One is shown in Figure 5.2.8. Changes often occur in food webs as the populations of different organisms increase, decrease or disappear altogether. Some animals or plants might be in the pond for only a short time each year. For example, tadpoles might be an abundant food source for fish one week, but if they become frogs the next week they will no longer be available to the fish. They could instead be a food source for the kookaburra. A food web clearly identifies what eats what in the whole ecosystem. There are at least three different food chains represented in the food web. Figure 5.2.8 algae snail large fish small fish pond weed 5.5 5.6Prac1 p. 197 194 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>211</Page_no><display_no>195</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review5.2 Remembering 1 State what the arrows in a food chain indicate. 2 Name the process that plants use to make their food. 3 State where the energy in a plant’s food comes from. Understanding 4 Define the following terms: L a producer b consumer c decomposer. 5 Explain why all food chains begin with the Sun. 6 Explain why a producer is the first living thing in a food chain. 7 Describe an example of each of the following: a competition between two carnivores b competition between two herbivores c a predator and its prey. Applying 8 a Use the f$:$IqPbgTcHND6lGidMbO75KhLTw1ymMnwsVu3sq41954xI7XM2Y4v3kCabDeMQUTn4l9szhpe96je0
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sLCRtVXJIbcI$:$ the producer, the first-, second- (and possibly third-) order consumers and the decomposers. c Imagine that the water the mangroves live in became so polluted that many of the crabs and prawns died. Predict what other organisms would be affected. d Predict what would happen to these other organisms. Sun leaves fall algae grow prawns, crabs, molluscs ﬁsh heron pelican humans mangroves Figure 5.2.9 10 Predict what could happen in the food web shown in Figure 5.2.10 if the number of: a small birds decreased b large birds increased c plants decreased. large bird small animal beetle small bird snail plants grub aphid Figure 5.2.10 Habitats and interactions 195 ]]></TextData></Page><Page><Page_no>212</Page_no><display_no>196</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review5.2 Analysing 11 Compare a food chain and a food web. 12 Compare carnivores, herbivores and omnivores. 13 Humans and sharks are often said to be ‘at the top of the food chain’. a Propose what this statement means. b Discuss whether humans and sharks can both be at the very ‘top’. Evaluati$:$6QkAocWHwuUXwMVYFvEnsyWEnvJYQLqNbJWgdGHcNCGRywudwcJ0V/bldUOjgbJBAV64lIu2IYQr
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BEMiKPsItmlgQ7PyckbgtNIkTndjtA==$:$ts algae and snails) • water beetle (eats small fish) • frog (eats beetles) • snake (eats beetles and frogs) • decomposers. 17 Using a set of six cards, write your own name on one card. On the other cards write the names of five plants and animals that you could eat. a Use these cards to construct a food chain in which you are: i a first-order consumer ii a second-order consumer iii the consumer at the end of the food chain. b Discuss how easy was it to make the food chains, and whether you had to make other cards. 18 Ecosystems rely on producers, consumers and decomposers. Design a role-play for each of the following situations. a All the consumers in an ecosystem are removed. b All the producers in an ecosystem are removed. c All the decomposers in an ecosystem are removed. Inquiring 1 Research a habitat in which you are interested or that is relevant to your local area. Find: • the plants and animals that live there • what animal eats what. Present your research as a food web for the habitat. 2 Research the food eaten by a koala, a great white shark, an emu and a Tasmanian devil. Deduce which of these animals would be most affected if one of their food sources disappeared. Present your research as: • a table that shows what each animal eats • a written paragraph that clearly identifies the animal that you think will be most affected • a written justification for your choice. 196 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>213</Page_no><display_no>197</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations5.2 Woolly web Note: This is a whole class activity. Purpose To construct a food web and use it to investigate the effect of change. Hypothesis Which organisms in a food web do you think will be affected by a change in it—the organisms in the food web above or below the change? Materials • information about feeding relationships in a particular habitat • small balls of wool or string (start with five for each student) • cards to make labels • marker pen • paper clips (one per student) Procedure 1 Each student selects an organism from the list of organisms found in the habitat. 2 Using a card and marker pen, create a name label so that you can be identified. Use a paper clip to attach it to your clothing. 3 Using the information about feeding relationships, identify the organisms that you will use as a source of food. 4 Start with the producer organisms. Connect the producers to the herbivores that eat them, extending the wool from the producer’s right hand to the herbivore’s left hand. The producer organisms and the herbivore hold opposite ends of a piece of wool. The wool represents an arrow in the food web. 5 The carnivores then connect to the herbivores they eat, by holding opposite ends of a piece of wool (wool from the right hand of the herbivore should extend to the left hand of the carnivore). 6 Any carnivores that eat other carnivores are then connected until all the feeding relationships are created by pieces of wool. The wool always goes from the right hand of the organism being eaten to the left hand of the predator. 1 7 Identify one organism that will be eaten—the prey. The student representing that organism gently pulls on one piece of wool so that the energy moves along the food chain from the prey to the predator. The predator then pulls on all of his/her strings so that the energy moves to the next level. Continue in this way until the energy reaches the consumers at the ends of all the food chains. 8 Repeat the exercise, starting with organisms at different levels in the food web. Results Observe the effec$:$ekp/AdnZYuXwRAAaaxfWGh9fUR1lPbjL+vrU/HH+FjfEP5zX6D90Oq2tC7P0OL6MDYE/8ds9IifK
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gzzchmD+5/AjVczJ4gsNCKT5jO+/wrhNtz0j7K1Mb9V/WtNrh6bfUIpPvytCLDFa6029Ww==$:$for your investigation. 8 Assess whether your hypothesis was supported or not. Habitats and interactions 197 ]]></TextData></Page><Page><Page_no>214</Page_no><display_no>198</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Environmental conditions in ecosystems change. Fire, flood, cyclone and drought may cause widespread changes that have $:$jmuS1ssBFLOT+GxOgvuLKLPWxcEX2JILpV6O6IBmxM6NfxaZwtTC/zRnd0KPQ7mPVg/LEbyvyh5h
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88D89CgCgs63KF3cwO8VKbXRNK7FSkdKUSHr5YtaLFfpQYjog8xBZ+3WXQ==$:$ems (like the one in Figure 5.3.1) there are a wide variety of species (different types of organisms). There are many different habitats for these species. Most species have a variety of food sources, so if one food source is in short supply they can use another. Natural ecosystems are sustainable ecosystems. Human activities can change ecosystems. This can result in sustainable or unsustainable environments. Humans can influence ecosystems so that species leave the ecosystem because their needs are no longer met. If the species cannot find a suitable place to live then it is in danger of becoming extinct. The valleys of the Blue Mountains are sustainable ecosystems that provide habitats for a variety of species. The needs of those species are met by the resources of the ecosystem. Figure 5.3.1 198 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>215</Page_no><display_no>199</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Traditional use of fire Fire causes rapid changes in ecosystems. Fire has been an important part of Australian ecosystems since before humans lived on the continent. In large areas of Australia the plants are adapted to fire. For example, some plants need fire to release seeds from woody seed pods. Others plants recover quickly after fire has destroyed their leaves. Indigenous Australians used fire as a tool for hunting. Kangaroos and wallabies escaping from the fire could be captured more easily by hunters. Traditional burning patterns used frequent cool fires, such as the fire in Figure 5.3.2. Forests were replaced by open woodlands and grasslands. There was an increase in grazing for animals, such as the kangaroos the Aboriginal people used for food. Plants used as food also flourished. Different areas were burned at different times, leaving a mosaic pattern which provided a variety of habitats for different plants and animals. In turn, this provided a variety of foods for the Aboriginal people. When Europeans arrived in Australia, traditional Aboriginal burning practices gradually stopped. Many of the ecosystems they had created changed. Fuel reduction burning To many people now living in Australia, fire is an enemy and something to be prevented. However, when there is a long time between fires, the amount of fuel available causes an intense fire like the one in Figure 5.3.3. When an intense fire goes through an area many of the native animals are incinerated and plants are killed. Traditional Aboriginal burning practices used cool fires that burned the grass and low shrubs without destroying the leaves at the tops of the tallest trees. Figure 5.3.2$:$mn0g11/WPdJms8MrZ3Tc21iuBQuhXVOPvB7jWD19Yt3ZPoz9mqTyy9mlsk4wY9h/6VMWobi9RfWC
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xsHd3DK1aOk4lTTfI2TIEfsM7GUmXiwkO1L5gwTHexe6/vNy6IPMQWft1l0=$:$After a low-intensity fire, animals such as kangaroos and wallabies move back into the area within a few days. Plants quickly produce new shoots, as seen in Figure 5.3.4. These shoots provide food for the animals. Intense wild fires are very destructive and may cause the death of large numbers of plants and animals. Figure 5.3.3 The Australian bush recovers quickly from a low-intensity fire. Animals return to the burnt area to feed. Figure 5.3.4 Habitats and interactions 199 ]]></TextData></Page><Page><Page_no>216</Page_no><display_no>200</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Conservationists are concerned that frequent burning reduces the number of different types of living things able to survive in an area. Scientists in Western Australia have studied the effects of FRB in a variety of ecosystems and have found that the variety of living things is not affected. That is, the ecosystems in the burnt areas still have all the same types of plants and animals as before, but the actual numbers of individuals may be less. Carefully planned burns can be used to create a variety of habitats. Unburnt areas provide a refuge for animals escaping the fire. Recently burnt areas provide habitats for animals that prefer open areas. The dense vegetation of areas left unburnt for a few years, provide small birds and other animals with protection from predators. Planned burns also create fire breaks that stop wildfires from burning particular habitats. Botanists recognise that fire is a necessary part of the environment. Botanists study thousands of plants to find out what happens to the plants during a fire and how regrowth occurs after a fire has gone through. Using this information botanists hope to be able to work out how frequently burning should take place and how intense the fires should be to manage environments so that they are sustainable. Fire monitoring technology Different parts of Australia have different times of the year when fires are most likely to occur. These times are known as the fire season. In southern Australia the 2001–2002 fire season was a bad one and following it, Austr$:$MNMtetZCH/2sm3tfWIuTpMB96m/CcVqTj+o6cBcCKgtGEloLf1g5Cdzs+K6t2i9+vKnEENXSHA4q
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wogqJq3lUCLsF3c=$:$eaches the lake, a completely different ecosystem is established. After remaining in the sand for years, the seeds of wildflowers germinate, producing large areas of colour. Fish and other aquatic animals flow into the lake with 5.7 MODIS alerts firefighters to the outbreak of fires. Decisions can be made to fight the blaze or just monitor it if the fire is in a very remote area. Fires appear as red areas in the haze of smoke. Figure 5.3.5 Lake Eyre as it is normally seen Surrounding desert after rain Lake Eyre fills after heavy floods When water reaches Lake Eyre, the ecosystem is changed from dry desert to an area with many different organisms. Figure 5.3.6 200 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>217</Page_no><display_no>201</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[the flood waters. Thousands of water birds, such as pelicans, cormorants and ducks, fly in and start nesting and breeding. The young birds are an abundant food source for predators such as dingoes and kites. A desert ecosystem returns when the flood waters dry up. Floods can destroy ecosystem$:$Vy2i1YSaeHVIr0vmcjzU0PobGgDxOYcpZIxlNeV9wUg7Ph4wpXhHm1hlcSqh5u0/wOGoc2qcupxA
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k0CRwi6bFQmQ2w87FPhIvbioA7AsHJCtpJupP6D1gWfyA7SwexHMRP/4at4GENE=$:$h. Many Australian cities and towns are built on flood plains because in the past, transport by boat was easy, and it was also easy to get water and to dispose of wastes. An example is Gundagai (NSW), shown in Figure 5.3.8. Flood plains are also fertile and good for growing food crops. Regular flooding adds nutrients and moisture to the soils but also means that the towns and businesses are damaged. As towns have increased in size, flood damage has increased. Floods such as the one that swamped Moree (NSW) in 2012 (Figure 5.3.9) cannot be prevented, but they can be managed to some extent. Brown sediments moving from the river into the ocean. The sediments cover plants and animals on the ocean floor. Figure 5.3.7 Any plan to manage the flood plains should consider different aspects of the situation. • There are natural ecosystems on the flood plains that need to be conserved. • People must still be able to live and work in the area without risking their lives or health. • When a flood occurs, the cost of property damage should be kept to a minimum. Gundagai is built on the flood plain of the Murrumbidgee River. The flat land makes building easy but the town may be flooded when river levels rise. Figure 5.3.8 Moree is flooded frequently. A flood plan is needed to protect as many homes and buildings as possible. Figure 5.3.9 Habitats and interactions 201 ]]></TextData></Page><Page><Page_no>218</Page_no><display_no>202</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Flood management Flood management can take different forms. • Raised banks called levees can be built to prevent water reaching buildings. Figure 5.3.10 shows a levee built around farm buildings. • Channels can be dug to carry the water away more efficiently. science fun Stopping the flood! Why are sandbags effective at stopping flood waters? Collect this … • 2 small buckets of water • 2 large shallow containers • small bucket of soil • 50 cm × 15 cm piece of cotton fabric Do this … 1 Using the fabric and half of the soil, make a long ‘sausage’ 3 cm in diameter of soil wrapped tightly in fabric. 2 Shape the ‘sausage’ into a circle and place it in the centre of one of the trays. 3 Use the remaining soil to create a circular wall in the middle of the second tray. 4 Carefully pour one bucketful of water i$:$8PWs1GI5i18fX1EdZT24y/9OUPY1bCjc5lW/SvEmFniuM/XQwfzPkW/jBelaBjtSDYE/8ds9IifN
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i956lICP3+O7pNCDs+85gUCcv9eEojqnIqUUdilWxdeN8k7Hl9faqXRkBF66Q9U=$:$on stumps. Floodwater surrounds this home but the living area is still dry. Figure 5.3.11 When floods occur they are not all the same height. Regional councils have flood maps drawn that show how likely it is that particular areas will flood. Using these maps, decisions can be made about the use of the land. For example, essential services such as hospitals, telephone exchanges and flood coordination centres should be placed in areas least likely to flood. Natural ecosystems could be maintained in the areas most likely to flood, or these areas could be used for playing fields and open space. Figure 5.3.12 shows the potential use of areas of a flood plain. The levee built around the farm buildings protected them from flooding when the surrounding area was inundated. Figure 5.3.10 Prac1 p. 209 202 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>219</Page_no><display_no>203</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Introduced species Many species of plants and animals have been introduced into Australia. These include: • most of the animals and plants we use as food • pet animals such as cats and dogs • animals used for transport and recreation such as the horse and the camel • many ornamental plants used in parks and gardens such as the jacaranda. The wool, cotton and leather used to make clothes and furnishings come from introduced species. The majority of the introduced species have benefited humans. The same is not true for other introduced species such as the fox (Figure 5.3.13), the rabbit and the cane toad. The fox was introduced into Australia from Europe in $:$WwqgvfyYZ1wKbdIoKLR1H5naUsnW6D1CYuZg3O6tw1yeDZnkufbXcF9J6JPLjkROxKny3T80ECfW
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smu2xIcu0nXfISD4PbEoNQdHr26cNeHQnx/DL1h4$:$ce Potential land use when no ﬂood protection in place Animal control Native animals such as dingoes kill lambs for food. Farmers build fences to protect their animals. Introduced animals such as rabbits compete with cattle and sheep for fodder. Dingo fence Dingoes were a problem for farmers in the late 1800s. Between 1880 and 1885 a fence was constructed to protect the sheep of southern Queensland from attack by dingoes. The path followed by the fence is shown in Figure 5.3.14 on page 204. The aim of the fence was to keep the dingoes out of the fertile areas of south- eastern Australia. The fence has brought benefits and disadvantages. The advantage is that fewer sheep are killed and eaten by dingoes. Also the numbers of emus and kangaroos are greater where there are no dingoes. The disadvantage is that the greater numbers of kangaroos and emus inside the fence compete with the sheep for the grass. This means that farmers cannot graze as many sheep per hectare. Wild camels are damaging the dingo fence. Plans are in place to build a taller fence that is electrified. Habitats and interactions 203 ]]></TextData></Page><Page><Page_no>220</Page_no><display_no>204</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Rabbit-proof fence Rabbits were introduced to Australia with the arrival of European settlers in Botany Bay on the First Fleet in 1788. The number of rabbits was very small to begin with but a further introduction in 1859 caused their numbers to increase rapidly. By the late 1800s rabbits were a plague and had spread across into Western Australia. Rabbits were damaging crops and eating all In many parts of Australia rabbits were present in plague numbers. Rabbits were clearing grazing land so there was nothing left for the cattle to eat. Figure 5.3.15 the grass, leaving nothing for the cattle to feed on. By digging their burrows rabbits were causing millions of dollars worth of damage to grazing land. Sights like those seen in Figure 5.3.15 were common. To protect their livelihood, farmers trapped and shot the rabbits in large numbers. The rabbit-proof fence (shown in Figure 5.3.16) was built to protect crops and grazing land in Western Australia. Construction of the first section of the fence was started $:$wgKFT+Ar9cUP3pqtd8JbWvWmmUHPCq19/SYkHoX8AFcQaFqD4eQhrA5ZUl+MD29W8B4QQXQc3iF8
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lyDoWw1pHJ2bMqZphJax0K6JVo9jLpw=$:$RTHERNTERRITORY SOUTHAUSTRALIA Perth Albany Esperance Kalbarri Dongara Karratha Wallal Downs Bremer Bay Jerdacuttup No. 1 fence No. 2 fence No. 3 fence Broome Eighty Mile Beach Eucla Before the first section of the rabbit-proof fence was completed in 1934, rabbits were found to the west. A second and then third section of fence were built. Figure 5.3.16 The dingo fence is 5614 kilometres long. It has successfully protected sheep and native animals from predation by dingoes. Figure 5.3.14 Coober Pedy Brisbane Broken Hill Sydney 204 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>221</Page_no><display_no>205</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Biological control One metho$:$tgO1dDQ1V+uJ84o+EloD/8CfvGfXw5eoN5O12gz0vYe0CNEcDs+zBETP1GRAGeGFfWjcD3j0oDfZ
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K6pV/xJM7o/aAxlArxc2S1AWNCdOoiAKOUNcxczdjbcTYA==$:$learning aCross sustainability Cactoblastis moth caterpillars Figure 5.3.17 The following are three examples of biological controls that have been tried in Australia. The Cactoblastis moth (Figure 5.3.17 and 5.3.18) was introduced into Australia in 1925 in an attempt to control the spread of the prickly pear cactus (Figure 5.3.19). The moths feed only on the cactus, and so they died out when they had eaten all the food. This was a big success and the problem of the cactus was solved within a few years. The cactus has not died out completely, but it is under control. The prickly pear cactus was brought to Australia by Captain Phillip on the First Fleet because it was a food source for a beetle that provided the red dye used for soldiers’ uniforms. Later it was grown as cattle feed and as a pot plant in gardens. The cactus spread very rapidly and at one stage covered an area the size of the state of Victoria. Figure 5.3.19 The Cactoblastis moth. The caterpillars (larvae) of this moth eat the prickly pear cactus. Figure 5.3.18 ADDITIONAL Habitats and interactions 205 ]]></TextData></Page><Page><Page_no>222</Page_no><display_no>206</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[ADDITIONAL Plagues of rabbits can quickly destroy the land. Scientists tried to control the spread of rabbits in Australia with poisons and viruses. Figure 5.3.20 Sometimes biological controls do not work as planned. An example of this is the biological control introduced to control rabbits in Australia (Figure 5.3.20). Rabbits eat crops and grazing lands, as well as burrowing (digging) through the soil until it can’t be used for anything. In 1995 a virus, the calicivirus, was being researched as a possible method of control. The virus was accidentally released into the wild ahead of schedule. In the first few weeks, millions of rabbits died. Grazing land regenerated quickly. The results looked promising until it was realised that the foxes that relied on the rabbits for food were now eating small native mammals instead. The most famous Australian biological control story is that of the cane toad (seen in Figure 5.3.21). Cane toads are native to South America and were first introduced in Australia in 1935 to control cane beetles. Cane beetles were accidentally introduced with imported sugar cane. As a control agent cane $:$V3XGyCLn9/ty8ClL91//Uiz3lzgalkHmOx/Csv+JFUCSUHG3nYm0oqd95gV8GkIV9pwKwqj3v4xt
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etNzguFI$:$nd down the east coast into northern New South Wales. This cane toad is eating a frog. review 1 Explain why the cane toad was introduced into Australia. 2 List two reasons why the prickly pear was introduced into Australia. 3 Explain why the introduction of the Cactoblastis moth was considered a success while the introduction of the cane toad is considered to be a disaster. 4 The search for biological controls is just one part of biological research. Propose reasons why society should support biological research such as this. EU CCT PSC 206 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>223</Page_no><display_no>207</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review5.3 Remembering 1 State the meaning of the following terms: L a fuel reduction burning b flood plain. 2 Name the method of controlling pests that uses natural predators. Understanding 3 Explain the difference between a cool fire and an intense fire. 4 Describe changes in ecosystems caused by the traditional burning practices used by Indigenous Australians. 5 a Explain how Indigenous Australians created a mosaic pattern in the vegetation. b Explain the benefits of having the mosaic pattern. 6 Explain the benefits of fire reduction burning: a for the wildlife in an area b for the firefighters responsible for the area. 7 Outline the benefits to wildlife of planned burning programs. 8 Explain why many towns were built on flood plains. 9 Describe two ways that floods can be kept away from homes and other buildings. 10 Discuss the benefits and disadvantages of having the dingo fence. Analysing 11 Compare a sustainable and an unsustainable ecosystem. 12 Compare the way Indigenous Australians used fire with the attitude of Europeans settlers to fire. 13 Compare two effects of floods on natural ecosystems. 14 Compare the reasons for building the dingo fence and the rabbit-proof fence. Evaluating CCT 15 A wheat field is not a natural habitat. However, the wheat field provides a habitat for organisms. Deduce the types of organisms that would thrive in this habitat. 16 In some forests only the largest trees are taken out by loggers. Propose changes that removing only the largest trees would have on the other organisms living in the forest. 17 Propose ways that observations using MODIS can help protect Australian homes, industry and farming land. 18 M$:$mv6mwVAcFj3N+tkdT4roSN0slRU/zFo42n0BFlIau2fdB6KXwKq4HJJV0NUhukN6xqsHZ3LEYpj1
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J1YZpxXugcNlHUY9XNvE6SN8VxiuxKtLJXpBUqREwTSh$:$ past 200 years more than 125 species of Australian native plants and animals have become extinct. Hunting, changes to the environment, and habitat loss have caused many more species to become threatened. Threatened organisms can be classified into one of three groups, depending on how great the threat to their survival appears to be. • Endangered species are close to extinction and very small numbers remain. Examples are the helmeted honeyeater, the blue whale, the beaked gecko and the Leadbeater’s possum (Figure 5.4.1). • Vulnerable species are experiencing a rapid population decline and are in danger of becoming extinct if the drop in numbers continues. Examples of vulnerable animals are the mountain pygmy-possum, the giant Gippsland earthworm, the Mallee fowl, the bilby and the diamond python. • Rare species have low numbers and are often spread out over a large area. Although the populations may be small, they are not decreasing. Rare organisms include the eastern wallaroo, the leafy sea dragon, the powerful owl and the alpine tree frog. Leadbeater's possum diamond python leafy sea dragon Threatened species of Australia Figure 5.4.1 210 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>227</Page_no><display_no>211</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Effect of an industry Sumatra is one of the islands of Indonesia. Its position is shown in Figure 5.4.2. It has a huge range of plant and animal species, some of which are found only on this island. The Sumatran elephant, Sumatran tiger (Figure 5.4.3), Sumatran rhino and Sumatran orang-utan are four species that are critically endangered because their habitat is disappearing. These species live in the rainforests of Sumatra. However, Sumatra has lost almost 50% of its tropical rainforests in the past 35 years. Sumatra Java Bali Timor Australia Irian Jaya Sulawesi Kalimantan Indian Ocean Timor Sea Celebes Sea Jakarta 0 800 km Sumatra is one of many islands that make up the country of Indonesia. Figure 5.4.2 Sumatra is the only place where this tiger is found. It is the smallest of the tigers and there are few$:$5z6jRiaDWSMOValU1qPITRH8di2RmrmJHmo98KTcooeqXbCj/302L9690dXOFvUybEty4xw3he6h
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iKJCqNdAMXM=$:$r the Sumatran tigers, orang-utans, rhinos and elephants. Figure 5.4.4 science fun I need mining and forestry What products of the mining and forestry industries do you use every day? Collect this … • paper and pencil Do this … Look around your home or school and list the products that are made of: • wood, paper and cardboard (from the forestry industry) • metal (from the mining industry). Record this … Describe the range of products you identified. Explain how your life would be different without these products. Habitats and interactions 211 ]]></TextData></Page><Page><Page_no>228</Page_no><display_no>212</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Logging Trees growing in Australia’s forests are a valuable source of timber. Timber is used in construction, furniture making and as wood pulp for the production of paper. Figure 5.4.5 shows how the forests, and the habitats the forests contained, are destroyed when the trees are removed. Animals’ homes and food so$:$qYp6xfZaoaHCpgBn/9QgJWsaFt1CqDrO5qQ++EObsoZVI0Wa0MzCGv9Mwm2a8nBgfczegmuVfImo
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OHXFYEP/7hJgFh5X7MmaF2Q0lTEFI6vYYUN0Kss/xCXJHjm0f3hyg0clBnwq$:$ed coal produces 89 per cent of the total electricity needs in NSW. Large trees provide food and shelter for a variety of organisms. These organisms all lose their homes when old trees are cut down. Figure 5.4.5 Mining occupies a very small proportion of the total area of NSW. However, mining has the potential to cause major damage to environments. Many coal mines are open-cut mines such as the one shown in Figure 5.4.6. In open-cut mining the surface soil and rock is scraped away to access the resource underneath. All the habitats that were there are destroyed. There have also been situations where poisonous chemicals from the mines pollute waterways, causing damage to these habitats and the organisms that live in them. Loose soil also washes into rivers and creeks and destroys the habitat of water plants, which cannot grow in muddy water. The mining industry in NSW is controlled by state and federal regulations. The aim of these regulations is to minimise any harmful effects on the environment. Before mining projects are approved, possible effects on aspects of the environment such as water, biodiversity, air quality, noise and greenhouse gas emissions are assessed. The possible effects on the environment are balanced against benefits to the community and the economy. For example, a mining company and state authorities will work together to reduce and repair some of these harmful environmental effects. Open-cut mines remove all the vegetation from the surface. The soil and vegetation have to be replaced when mining is finished, but that is too late for the animals that have lost their habitat. Figure 5.4.6 212 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>229</Page_no><display_no>213</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Agriculture In Australia, a large proportion of the total land area has been cleared of native vegetation (the plants that usually grow there). The land is now used to graze animals or to grow crops such as the wheat seen in Figure 5.4.7. These agricultural areas provide very different habitats from the native vegetation. Fertilisers and pesticides used on the crops may wash into rivers from the farmland, causing changes in river and wetland ecosystems. Scientists have developed new varieties of crops and breeds of animals better able to cope with Australian conditions. Scientists have also developed ways of growing consistently good quality fruit and vegetables that can be produced as cheaply and quickly as possible. Salt-tolerant wheat In parts of Australia soils have a high salt content. The salt occurs naturally, but some land management practices have brought the salt closer to the surface. Not all plants can grow in salty soils and as the area of salty land increases the amount of food produced decreases. If salt reaches the leaves of wheat, the plant cannot carry out photosynthesis. Durum wheat, shown in Figure 5.4.8, is used to make pasta and couscous. Durum wheat is particularly sensitive to salt and about 69 per cent of Australia’s wheat-growing area is affected by salinity. In 2012, Australian scientists from the University of Adelaide produced a variety of durum wheat that is ab$:$g4I6rOrWM5B1W65FjPzFSBVCmkmc0IkZY0xv8+1kbzggTo8ImaDpILDuAqNNvFqeJPIDSALZmBAg
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wOk=$:$n about 15 years of research to create this new variety. Now that scientists have been successful in making salt-tolerant durum wheat, they hope to use this knowledge to create a variety of bread wheat that is able to grow in salty soils. Durum wheat is used to make pasta. Its yield is very low when it is grown in salty soils. Figure 5.4.8 Droughtmaster cattle Cattle are not native to Australia and most were imported from Europe. The conditions in Australia are very different from Europe and farmers often struggled to keep their cattle in good condition for the beef market. In the early 1900s, pioneer cattle breeders in North Queensland saw a need for cattle that: • could tolerate hot weather • could make best use of the limited nutrition provided by the native pasture grasses • could walk long distances to access water and feed • were resistant to ticks • produced good quality meat • give birth to their calves easily. Habitats and interactions 213 ]]></TextData></Page><Page><Page_no>230</Page_no><display_no>214</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Brahman cattle, seen in Figure 5.4.9, originally came from India. They have more sweat glands than European cattle, which makes them better able to tolerate hot weather. Their oily skin helps repel insect pests and they are more resistant to parasites and disease. Shorthorn cattle are a breed from the United Kingdom that produce good meat. Some of the original Australian Shorthorns came from England with the First Fleet. By 1820 the NSW colonies were self-sufficient in meat by grazing Shorthorns. Cattle breeders mated Brahman cattle with beef Shorthorn. This process of mating one breed of cattle with another is known as cross breeding. At each generation the offspring that showed the best characteristics were selected and then mated. After many years of cr$:$ez1+Y0g/ivkh5FRHG2RPefzlteoN4pA58qlsMiNFp853ZJiG+lpgGob9aRJUFBJhFTRKzcrYqVtQ
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3lHn2qNR6Lc4o4A=$:$an and Shorthorn cattle. The red colouring is not just in their coat, it is also in their eyes giving them protection against eye cancer. Figure 5.4.9 parts of only one parent plant. When they reproduce in this way the offspring (babies) are exactly the same as the parent. The offspring are clones of each other. Cloning of plants has been used by farmers and gardeners for centuries. The advantages of cloning include: • Thousands of plants can be produced from one parent plant. • The best plants can be selected for cloning—plants that are resistant to disease or produce larger, sweeter or more colourful fruit. • The quality of the plant or the fruit is known from the beginning. • Cloned plants all grow at the same rate and therefore all fruit is ready for harvest at the same time. The disadvantages of cloning: • All plants are identical therefore all will be likely to be attacked by the same pests and affected or possibly die from the same diseases. • Cloned plants are often sterile. This means that they do not produce seeds from which new plants can be grown. If the plant population was wiped out there would be no way of growing plants to replace them. Banana suckers Banana trees grow suckers—young trees growing from the base of the parent tree as shown in Figure 5.4.10. Banana trees grow from suckers produced by the parent plant. The fruit from the suckers and parent are equal in taste and other qualities. Figure 5.4.10 214 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>231</Page_no><display_no>215</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The bananas you buy in the shops have all been grown by suckers and are all exactly the same. A disadvantage of them being the same is that all the trees will be affected in the same way by disease. There are diseases of banana trees that could destroy the whole banana crop in Australia. This is why there are restrictions about bringing banana trees into Australia from overseas and moving banana trees around the country. An advantage of the trees being the same is that the fruit they produce is also the same and bananas in the shops are all of the same quality. Grafting fruit trees People who grow fruits such as apples, oranges, avocados and grapes need to guarantee the quality of the fruit they produce. Horticulturalists are scientists who study the growing of plants. Horticulturalists grow fruit trees from seed. These trees have different characteristics. When the horticulturalists find a tree that produces very good quality fruit they will take cuttings from the tree. Cuttings are part of the stem, leaf or root that is able to grow into a new plant. Hundreds of cuttings can be taken from the same parent tree. These cuttings are grafted onto existing root stock using the technique shown in Figure 5.4.11. A large orchard with hundreds of trees all producing fruit of the same quality can be established relatively quickly. Garden plants by cutting Many of the plants you find at a nursery, garden centre or hardware store, like the plants in Figure 5.4.12, are grown from cuttings. These cuttings are not grafted. They are treated so that a leafy shoot produces roots and becomes a complete new plant. Thousands of plants all identical to each other are produced from a single parent plant. By using cloning gardeners can be sure that the plants they buy have the characteristics they want. Twigs for fruit trees with desirable characteristics are grafted onto the root and trunk of an established tree. Figure 5.4.11 Prac1 p. 219 Prac2 p. 220 Prac3 p. 221 The hundreds of plants in this nursery are grown from cuttings from a parent plant that has the characteristics the growers want. Figure 5.4.12 Urbanisation Towns and cities are built $:$+4TF1cBe3CyX18Q524vr6ExLx0bM+gww19zwr9kEEYbwEWUO49rZCV8WcAJEaBDr1GTQX4PY1o5C
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QNlDTMBk3E58d3q++DaehLRNsLYQls4fW17XOQZV/xJM7o/aA/6lDgP3ML26YpmpVPT2eFY=$:$nce found in the Ravensworth State Forest. Figure 5.4.14 regrowing a forest Ravensworth State Forest is one of the largest areas of remnant woodland in the Hunter Valley of New South Wales. Remnant vegetation is native vegetation that has survived when areas around have been changed by activities such as grazing or forestry. A number of threatened species live in this forest such as the squirrel glider and the spotted-tail quoll, as well as several species of bats. The green and golden bell frog (Litoria aurea), shown in Figure 5.4.14, is a threatened species that lived in Ravensworth forest in the past. Existing ponds have been improved with the aim of reintroducing this frog and other amphibians to the area. Ravensworth State Forest was used for grazing and as a source of timber for more than 100 years. Logging ceased in 1986 and grazing was stopped in 1995. However, a coal mine was established in the area in 1993 and it is still in production. To compensate for disturbing the forest, the mining company purchased 430 hectares of neighbouring land, which has now been included as part of Ravensworth State Forest. The company that owns the mine is working with government bodies and experts from the University of Newcastle to reconstruct areas of forest. The aim is to create more sustainable habitats for threatened species and other species living in the area. Scientists are carrying out research to find the best ways of: • conserving the existing plant and animal life in the area 216 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>233</Page_no><display_no>217</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review5.4 Remembering 1 List three ways in which humans can affect ecosystems. 2 Name two Australian species for each category below: a endangered b vulnerable. 3 Name the breed of cattle developed to meet Australian conditions. 4 Recall the characteristic that helped the new variety of durum wheat survive in Australian soils. 5 Name three methods of producing cloned plants. 6 Look around you. List ten objects or materials in the classroom that have been obtained from mining or forestry. Understanding 7 Define the following terms: L a cross breeding b cloning. 8 a Define the term open-cut mining. L b Explain how this type of mining causes damage to the environment. 9 Explain why the movement of banana plants around Australia is controlled. 10 Describe the advantages to Australian agriculture of having salt-tolerant wheat. Applying 11 Identify the useful characteristics of Droughtmaster cattle that came from: a Brahman cattle b Shorthorn cattle. 12 Identify the advantage to a gardener of buying cloned plants to plant as a hedge round the boundary of a garden. Analysing 13 Compare the three groups of threate$:$SNy5LmldWqPE+u2ZLYEvE8s9bPT52wkmy8uiIbGM6NcusigwHH7/Kb5xwj+ZbPYqlqYZzMRtxucr
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vvNWebC7rxk=$:$row into a new plant Endangered species: species that are close to extinction and very small numbers remain Extinct: term used to describe a species that has not been seen in the wild for over 50 years, and of which the last known individual has died Horticulturalist: a scientist who studies the growing of plants Rare species: species that has low numbers, often spread out over a large area; the population is not decreasing Remnant vegetation: native vegetation that remains unchanged when surrounding areas have been changed by activities such as grazing or forestry Vulnerable species: species that is experiencing a rapid population decline and is in danger of becoming extinct if the drop in numbers continues Endangered species Vulnerable species 226 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>243</Page_no><display_no>227</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[6 Classification • construct keys to represent patterns or relationships CCT N L • identify reasons for classifying living things • classify a variety of living things on the basis of structural features • use simple keys to identify a range of plants and animals L • outline the structural $:$xibs5jpwbArEh9ySHsCkmvWu8Of+NUw6ZK9icIbYHf9N6CPPVMtxX3mCGk/k6EeB1nDxL0HhbxZe
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txNg$:$different groups, and again list the items included in each group. science fun Record this… Describe how you decided what to include in the groups. Explain which of the groupings was most useful. 228 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>245</Page_no><display_no>229</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[You use it every day Classification is the process of putting things into groups. It is a skill needed in many areas of life, not only in science. Next time you walk round a supermarket, think about the way products are grouped. Biscuits are all in the same aisle, with the savoury biscuits separated from sweet and chocolate biscuits. $:$8iCGoYHGfNymoHC7y+TPk9TM+kcxAe5k2VXAIxRkuCi6ISrdMlz+9DvhGz1DsJhIbBC96Iv8aFqz
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7NgpIAtL/0oHWzPOS7a6$:$o make it easier to communicate with other people. Giving an object, substance or organism a name ensures everyone knows what they are discussing. In order to classify something, you have to find out its characteristics and make a judgement about how similar it is to other things. amethyst Chemists group substances according to their characteristics. Copper is classified as a metal, along with iron and tin. Amethysts form purple crystals and can be grouped with other crystalline substances such as sugar and salt. Figure 6.1.5 copper The red fox (Vulpes vulpes) is a pest but it does help to control another pest species— the rabbit. Figure 6.1.4 230 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>247</Page_no><display_no>231</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Classification is an important skill used in all branches of science. Scientists observe ways in which objects are similar and group them together. Chemists classify substances such as those in Figure 6.1.5 and group them using names such as metal or non-metal, and acid or base. Geologists classify rocks as sedimentary, igneous or metamorphic (Figure 6.1.6), and astronomers classify heavenly bodies into groups such as stars, planets, comets and meteors. Introducing keys Biologists classify living things. Scientists who specialise in grouping and naming living things are known as taxonomists, and the science of grouping and naming things is called taxonomy. Once the characteristics of organisms have been described this information can be used to develop a key. A key is a tool that can then be used to identify unknown organisms. Geologists classify rocks usin$:$Hc4RsLx4LjTK9KpIXhTlpbY10hr0y3U535V5NYcywhq9sRavX+S4tg533/TNTw3kHzMpVD4Xv/vL
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hVJV48yCDvvhA+0i+oapSmqIjI8ih8Ym7OY6cGwKWUoGUA+oWkw=$:$ed to make the choices are easy to observe, with everyone knowing exactly what they mean. Take height as an example. A person’s height is easy to observe, but words such as tall or short can be interpreted in different ways. You would probably describe someone taller than you as ‘tall’. As Figure 6.1.7 shows, that same person might be described as short by an even taller person. Therefore tallness is not a good and reliable feature for a key. Descriptions of height such as ‘greater than 1.5metres in height’ are more reliable. Two ways of writing keys are as flow charts or tables. Buttons have been used to construct the two keys shown in Figure 6.1.8 on page 232. I think she’s short! We can all agree that I’m 1.7 metres in height. I think she is really tall! Qualitative descriptions, such as tall or short, are subjective, with different interpretations, but quantitative measurements are not. Figure 6.1.7 Classification 231 ]]></TextData></Page><Page><Page_no>248</Page_no><display_no>232</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Buttons Round 2 holes Plain Plain Blue Red 2 holesStriped Striped 4 holes 4 holes Three sided Four sided Straight sided Table key$:$VjZR+xt7uEj5fgnRRXZbhAM/f9l6Ph4nhBT/uqdC6XTL4OcMp2UpZe9WwAIWXugmywA6iNeTUbCd
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$:$5 234 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>251</Page_no><display_no>235</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[13 Compare how easy it is to use table keys and flow charts. 14 Analyse the cars in a car park and list characteristics that could be used to classify them. Evaluating CCT 15 In the property section of some newspapers, houses are listed under their suburbs. a Explain how this makes it easier for people to buy a house. b Propose other ways houses could be listed. 16 a In the key shown in Figure 6.1.16, identify which features make it a strong key and which are not useful. b Justify your decisions. 17 a Identify which of the following characteristics would be useful when constructing a key to identify varieties of dog: • loud bark/quiet bark • pink tongue/black and pink tongue • short hair/long hair • large ears/small ears • wags tail/does not wag tail • black/brown • straight hair/curly hair • hair hangs over eyes/hair not over eyes. b Justify your choices. Figure 6.1.16 Long hair Short hair Boys Pony tail Hair loose Brown eyes Blue eyes Plays soccer Does not play soccer Cannot roll tongue Can roll tongue Class Girls Creating CCT 18 Construct a key using these terms: cricket playing field soccer tennis racquet chess netball tennis hockey stick squash court 19 a Construct keys that could be used to identify the objects from Figure 6.1.14 and 6.1.15. b Share your key with other members of the class. Compare the choices that were used. Inquiring 1 In most newspapers there is a section for advertisements called ‘Classifieds’. • Recall the meaning of the word classification. L • List some of t$:$Ht49ggeBGSwWXZVUEn/2wXl0epWGBG4FhWa1+5qavvo88tS+Yl6GxiVmvoyExIE6nRgxuhlSzWFe
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DtsnwuNS5HwhGwxC7nc5x+3EtdNIXEY1NiRxjLmqDt6d5dw10UFzkH+Ypr9ROH8m9ldfuynA$:$larities and differences these observations reveal, taxonomists have grouped all the known members of the animal kingdom into nine smaller groups. Each of the smaller groups is known as phylum (plural phyla). The nine phyla are shown in Figure 6.2.2. Poriferans Poriferans are commonly called sponges. A typical sponge is shown in Figure 6.2.3. Poriferans live in the water and most are found in marine environments. They are full of holes (pores) through which water passes, carrying their food. They filter the food out of the water, and for this reason they are known as filter feeders. The wastes along with water are pushed out through an opening at the top of the sponge. Animals Poriferans Cnidarians Echinoderms Annelids Nematodes Platyhelminths Molluscs Arthropods Chordates Eight of the animal phyla in this key do not have backbones. The phylum Chordates includes all the animals with backbones. Figure 6.2.2 This yellow tube sponge grows to about 80cm tall. It pushes so much water through its body as it feeds that divers can feel a current of water near the top of it. Figure 6.2.3 238 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>255</Page_no><display_no>239</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Cni$:$u0772uvPYxx8QNDxbhYA/U/Fi8n6Q7AoQQ95pitGDhlGDx4mp5Zb6MbHBBk/pyqswzaDE/DSDWKX
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p0hGaZlPGqlD4AejqAo=$:$f the box jellyfish (Chironex fleckeri) is one of the most poisonous in the animal kingdom. The poison causes the animals that tangle in the tentacles to have a heart attack. This can happen to humans too. The box jellyfish is responsible for 100 human deaths per year. Figure 6.2.4 Symmetry in organisms Organisms are often described as having radial symmetry or bilateral symmetry. Radial symmetry A cut in any direction through the middle will result in identical halves. Bilateral symmetry There is only one position where a cut produces identical halves. bilateral radial Echinoderms Starfish, brittlestars, sea urchins and sea cucumbers belong to the echinoderms. They all live in the ocean, often near the coast. Starfish, brittlestars and sea urchins have a spiny skin, which you can see in Figure 6.2.5, but the skin of sea cucumbers is leathery. One thing common to all echinoderms is that they have radial symmetry. Annelids The most familiar annelid is the earthworm, shown in Figure 6.2.6. Other annelids are leaches and ragworms (often used as bait for fishing). Look closely at an annelid and you will see rings along the length of its body. These rings are segments or divisions within the body, and give the group their common name of ‘segmented worms’. These animals have bilateral symmetry. Annelids are found in water and in damp places on land. There are over 6000 species of echinoderm. This picture shows two species: an orange starfish, and the black spines of a sea urchin. All echinoderms have a chalky layer under their skin, which forms a protective armour. Figure 6.2.5 Annelids have two body openings—one at the front where food enters and one at the back from which wastes leave. Figure 6.2.6 Classification 239 ]]></TextData></Page><Page><Page_no>256</Page_no><display_no>240</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Nematodes Nematodes are ‘roundworms’. They have bilateral symmetry like annelids, with long tapered bodies that are pointed at each end, but they do not have segments. They are commonly found in damp soil, in water, and as parasites in the bodies of other organisms. Parasites are organisms that live on or in another organism, called a host. They get their food from the host, but the host gets nothing in return and may be harmed. Heart worm, a common disease of dogs, is caused by a nematode. Even humans can be hosts to parasitic nematodes, like the one shown in Figure 6.2.7. Platyhelminths Platyhelminths are flatworms. They have bilateral symmetry with the body flattened top to bottom (Figure 6.2.8). They live in water or very moist places. Ascaris lumbricoides is a parasitic nematode that inhabits the human intestine. They can grow up to 35cm in length. You would know if you were infected with them because they cause stomach pain, vomiting and diarrhoea. Figure 6.2.7 There are over 12000 species of platyhelminths. Some are scavengers, cleaning up the wastes in the oceans and waterways, some eat microscopic animals, but many are parasites. Figure 6.2.8 Molluscs Molluscs are members of the second largest phylum in the animal kingdom. Snails, slugs, oysters and mussels belong to this group. All of them live in water or in very moist places. They come in a wide variety of shapes and sizes, but all hav$:$kOHCCf6Zftag2n2LA3ui/720aaI/CquorkljUQxrh3o746cRinNqCNNFe2+HIy3Eb5hqvKPFxyGG
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K/S5MiHI8rQ/v6jmwhofMOMHv2AHLoX9pwAp98Nm8EUTrP58$:$alled vertebrae, and together they are called the vertebral column or backbone. The group of chordates that has a backbone is commonly called the vertebrates. The bird shown in Figure 6.2.11 is an example of a chordate. 6.4 Birds are examples of chordates. They have a spine and spinal cord. Figure 6.2.11 Spineless? All chordates have a nerve cord but not all have a backbone to protect it. Some have a rod of cells known as a notochord lying below the nerve cord. Adult sea squirts look just like a bag of jelly. They filter food from the water and then squirt out the water when they are finished with it. All chordates have bilateral symmetry. They are divided into classes based on a range of characteristics that includes the way they breathe, their skin covering, body temperature, and how they reproduce. The eight classes of chordates are shown in Figure 6.2.12. There are three classes of chordates that are commonly called fish: Agnatha, Chondrichthyes and Osteichthyes. They all live in water and breathe using gills. They are ectothermic, which means that their body temperature varies with the temperature of the water they live in. Agnatha The agnatha are jawless fish. There are many fossils of jawless fish, but the only living representatives are hagfish and lampreys like the one in Figure 6.2.13. They have an internal skeleton made of cartilage. This is more flexible than bone—it is cartilage in the wobbly bit at the end of your nose. Agnatha have a fin along their backs. Their mouth is a round sucker, lined with horny teeth, which they use to attach themselves to other fish. All agnatha are parasites. Chordates without backbones Chordates Agnatha Chondrichthyes Osteichthyes Amphibians Reptiles Aves Mammals Classes of chordates Figure 6.2.12 Lampreys are shaped like an eel. Their mouth is like a suction cup that attaches the parasite to its host. The horny teeth inside the sucker scrape the skin away so that the lamprey can suck blood. Figure 6.2.13 Classification 241 ]]></TextData></Page><Page><Page_no>258</Page_no><display_no>242</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Chondrichthyes Sharks and rays belong to the class of chordates called chondrichthyes. Their skeleton is also made of cartilage, which gives them their common name of cartilaginous fish. Unlike the jawless fish, they have proper jaws and teeth. Sharks and rays have fins on the side of their bodies as well as along their backs as shown in Figure 6.2.14, and this helps them to be agile swimmers. Osteichthyes The osteichthyes are bony fish. They have fins on the back and sides of their body and have proper jaws and teeth. What makes them different from the other fish is their skeleton made of bone. Tuna, goldfish, eels, sea horses and lungfish all belong to this group. Figure 6.2.15 shows a barramundi, an example of a bony fish. Rays are members of the class Chondrichthyes. Their side fins are extended to resemble wings. Figure 6.2.14 6.5 The barramundi (Lates c$:$a9gSwwAib8qptdGKT5mZ2phA3LUE8AEXU/pWI2EHrzXawa1RqmMBQw87Yu6p4grTYLxF+Q1VPE4z
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D9nq8HKhd7EeK164j5Q3IjXILf8Fp9ORwaM+2KURHs1LrsJwpGjBxC3hI41nTXJiOTgWtkli$:$ians also take in oxygen through their skin. To be able to do this their skin must remain moist. Reptiles Reptiles such as snakes (Figure 6.2.17), crocodiles and lizards are ectothermic, and have a dry, scaly skin. They breathe using only their lungs. Generally they lay eggs with a leathery shell on land. While most spend their whole life cycle on land, there are exceptions. Sea snakes spend all their lives in water, and some cannot move on land at all. Sea snakes do not lay eggs; instead they give birth to live young. Some land snakes and lizards also do this. Amphibians must keep their skin moist, and usually live near water or in very moist places. They are all ectothermic, and therefore they are not found in very cold areas. Figure 6.2.16 The common death adder (Acanthophis antarcticus) is widespread throughout New South Wales. They feed on small animals such as frogs and birds but are not shy of humans and may attack if disturbed. Figure 6.2.17 242 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>259</Page_no><display_no>243</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Aves Aves is the biological name for birds. Birds are different from other groups because they have feathers covering their body and lay hard-shelled eggs. All birds have wings, including those that can’t fly, like the penguins in Figure 6.2.18. (Bats are the only other chordates with wings, but they are mammals.) Birds are endothermic, meaning that they generate their own heat and are able to control their body temperature. This allows them to remain warm in cold environments. Mammals The class Mammals includes all the animals that have a body covering of hair, and feed thei$:$T1vLoxNuF37Jj8S+E9NzhpfbM4aXveo31IfKjQKfAgkprqxLWCrLJ8Zdp3AmKcC8kFbqZhbDKhsf
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2zz7ylGZZd690dXOFvUy0bDBwwPXC+7s/aoALkpFog==$:$centals are mammals that nourish the baby inside the mother’s body by a placenta and the baby is born at a more mature stage. Placental mammals include seals, dingoes, horses, humans, humpback whales and flying foxes (Figure 6.2.19). • Monotremes lay eggs; this subclass consists of two species of echidna (one species is shown in Figure 6.2.20) and the platypus. • Marsupials such as the wombat in Figure 6.2.21 give birth to a tiny undeveloped young that climbs into the pouch where it is fed on milk. The young marsupial grows and completes its development in the pouch. The grey-headed flying fox (Pteropus poliocephalus) is a placental mammal found in Australia. Figure 6.2.19 A short-beaked echidna (Tachyglossus aculeatus) is a mammal that lays eggs—a monotreme. Monotremes are found only in Australia and New Guinea. Figure 6.2.20 The hairy-nosed wombat (Lasiorhinus krefftii) is one of the 140 species of Australian marsupials. Most of the world’s species of marsupials are Australian. Figure 6.2.21 Prac1 p. 248 Classification 243 ]]></TextData></Page><Page><Page_no>260</Page_no><display_no>244</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[the CurriCulum learning aCross critical aND creative thiNkiNg Is thIs a real anImal? Leading up to the seventeenth century, naturalists in Europe had described, named and classified many living things. They were confident that they understood the animal kingdom and that their classification system would be able to include any new species that were discovered. Explorers to Africa and America tested these ideas when they brought back creatures never seen before, such as giraffes, opossums, hippopotamuses and armadillos (Figure 6.2.23). A bigger stir was yet to come! Animals such as the armadillo (Dasypus novemcinctus) and the hippopotamus (Hippopotamus amphibius) tested European scientists’ systems of classification. Figure 6.3.23 In 1798 the Governor of New South Wale$:$DeLohGpGyMNkrFWz7klONCpmgwBTP4BfrlCNeo9ZkvVn+g0BMim2qba46m0wnRJoPnLXzQ7xmKhk
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wd3NSTAjPTFClGQG7MauIuiDzEFn7dZd$:$imens of skins, like the one in Figure 6.2.24, and skeletons arrived and were examined by Dr George Shaw, an experienced naturalist. He wondered if the animal was a hoax or trick. At that time, Chinese sailors had a reputation for their skill in stitching together parts of different animals to create a non-existent animal that they then sold to European sailors. Despite very close examination, George Shaw could not find any evidence of this being a hoax. There were no cut marks or stitched parts. When explorers first described a platypus it caused problems for taxonomists. Figure 6.2.22 ADDITIONAL 244 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>261</Page_no><display_no>245</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Using dried skins like this one, European scientists tried to imagine what a platypus looked like and how it lived. It is not surprising that they were confused at first. Figure 6.2.24 Complete, preserved specimens arrived in 1800, accompanied by descriptions from people who had observed the animal. Shaw was then able to confirm that the animal was no hoax and no freak of nature. It was a new type of anima$:$utvmJDb6x7ACWpeWK/YariubqYEAWCxgZ7feH40w6lwdEcgSlPBBftM7NlttIxcCCTqpCTfRIgvp
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1fxKi6Qvi8XPkfdBXdZWLeiDzEFn7dZd$:$ this new animal in detail and decide how to classify it. A new group of mammals was created—the monotremes. This group includes the platypus (shown in Figure 6.2.25) and echidna. revIew 1 Explain why scientists first thought that the skin of the platypus was a hoax. 2 Propose why the classification systems of the eighteenth century were not able to include animals such as the giraffe, the kangaroo or the platypus. 3 Discuss reasons for the platypus being so difficult to classify. Using electricity When the platypus dives to find food it closes its eyes and nostrils. It cannot see, nor can it smell its prey. The platypus searches for food using its electro-sensitive beak. The beak is so sensitive it can detect tiny electrical signals from the muscles of small arthropods and worms as they move around. The large webbed feet of the platypus make it an efficient swimmer. The duck-like bill is used to find prey in muddy creek beds. Figure 6.2.25 ADDITIONAL Classification 245 ]]></TextData></Page><Page><Page_no>262</Page_no><display_no>246</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review6.2 Remembering 1 List the nine phyla of animals. 2 Name the phylum that describes the largest number of types of animals. 3 Name the phylum to which humans belong. 4 List evidence that would show that animals are living in the garden. Understandin$:$UKb1Sc9WKd6RAexid8t2isFG4Ug3mPYzG1nKodXAajZhLV7J7xG+EGR+gv3+iA/DJyM6U18hwy2f
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iydEruAUJDtxVIHGhlU6t4+S+DHJDKp8bxBu6NI/ABW+$:$al symmetry. 8 An African elephant can have a mass of 5000kg and the mass of a blue whale can reach 190000kg. Calculate the number of times heavier a blue whale is than an elephant. Figure 6.2.26 N The largest mammal on Earth is the blue whale. Figure 6.2.27 Analysing 9 Compare annelids with nematodes by listing their similarities and differences. 10 Contrast an endothermic animal with one that is ectothermic. 11 Compare the characteristics used to classify: a a shark and a barramundi b a frog and a lizard c a kangaroo and a platypus. 12 Contrast platyhelminths and nematodes. 13 Use the following description to classify the organism. This organism was collected from the ocean. It has a soft body with long tentacles. After I touched the tentacles my hand was stinging. Evaluating CCT 14 Examine the animals shown in Figure 6.2.28. a Classify each into a phylum. b Justify your decisions. 15 Propose reasons why animals without a skeleton often live in water. Figure 6.2.28 i ii 246 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>263</Page_no><display_no>247</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[16 Select information from the pages on animal classification to complete the table below. Phylum Where it lives Symmetry Number of body openings Type of skeleton Other features Creating CCT 17 Copy the Venn diagram in Figure 6.2.29 into your workbook. Use this to compare the three chordate classes commonly called fish. Figure 6.2.29 Agnatha Chondrichthyes Osteichthyes 18 Construct a mnemonic to help you remember the animal phyla. Inquiring 1 Research the platypus to find answers to the following questions. • What does it feed on? • Where does it nest and have its young? • Does it incubate the eggs like a bird? If not, how does it protect its young? • How does it feed its young? Add some m$:$plcEAwtMfhrS02U5vuughaZ+Lbw07huduK0L1m3Pnb24Qa/95TcId56H4EdkG7TbegE5FSy62ANy
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CMxCzQG15A==$:$een these five animals and the animal you researched. Present your research as a poster, information leaflet or PowerPoint presentation. ICT 4 Research the arthropods. • Find out the ways in which taxonomists divide the arthropods into smaller groups known as classes. • List the characteristics used by scientists to separate the classes. • Find images or video of animals in each class. • Identify two classes of arthropods that include animals that can be harmful to humans. • Explain why these harmful animals (and other members of the class) are important in other ways. • Construct a dichotomous key for the phylum. • Have other members of the class use your dichotomous key. Evaluate the usefulness of your key based on feedback. Present your findings as a poster or digital presentation. ICT Classification 247 ]]></TextData></Page><Page><Page_no>264</Page_no><display_no>248</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations6.2 Classifying animals Purpose To use structural features to classify animals into their different phyla. Materials • multiple photos or printouts of animals from the 9 different phyla (at least 2 animals per phylum) • assorted skeletons, shells, preserved specimens, fossils Procedure 1 Copy the table from the Results section into your workbook. 2 Around the laboratory are photos, skeletons, preserved specimens and fossils of a variety of different animals. Move around the laboratory and for each animal record: • its name/s (common and/or biological) • the type of specimen you looked at (photo, skeleton, preserved specimen or a fossil) • its distinctive characteristics and structural features. 1 SAfETy The liquids used to preserve some older animal specimens are hazardous so do not use any specimens preserved this way. Results 1 Use your observations to complete the results table. An $:$U1Hu8rLrhXeaADef4DvDbN3YEfOzQQw00APpPmD8wCWyEZljf0vagxd6aWyxbrNOMvRCR+Fz5Nds
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S2ftQ0paSvcTuLec6t31vMRp50DvqSihU+8fJvDYwm6lSIoN7i+l7WRiKJAdvShvkDaw/37t/Q==$:$nifers Flowering plants Seed-producing plants Key to the plant kingdomFigure 6.3.2 Mosses are low-growing plants forming a mat on a rock, tree or soil surface. Figure 6.3.3 Spores are produced in special structures known as sporangia. Moss sporangia can be seen in Figure 6.3.4. They grow from the top of the leafy moss plant. The spores develop in the capsule at the end of the stalk.When the spores are ripe the capsule opens and the spores are blown out by the wind.When the spore lands in a suitable area, the spore will grow into a new moss plant. The capsule and the stalk together form the moss sporangium. The spores develop inside the capsule. Figure 6.3.4 Ferns Ferns have a vascular system for transporting food and water throughout the plant. They also reproduce using spores produced in structures known as sporangia, like those in Figure 6.3.5. Ferns have been around for a very long time. The first ferns appeared on Earth about 360 million years ago – long before flowering plants. Ferns vary in size. Azolla (seen in Figure 6.3.6) is a water fern that is only a few centimetres across. In contrast, tree ferns such as the lacy tree fern in Figure 6.3.7 can grow to a height of 15 metres. The spores are produced in the dark spots (sporangia) on the back of the fern leaf. Figure 6.3.5 250 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>267</Page_no><display_no>251</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Seed-producing plants Seed-producing plan$:$GYA0jybiR8DiEdLpQa3Nao9nw0GOKHlevhDHSwjGVWFk987qupWLMnF8NQhMoiD8kiTC6zdlRZqc
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QkhNy7fitYL4tkeiChuUGBdR8vGtxn+u7A0F$:$ure 6.3.8) • ginkgo (Figure 6.3.9) • conifers • flowering plants. Largest flower The largest flower in the world is found in South- East Asia. It can be up to one metre in diameter and weigh 11kg. Its name is Rafflesia arnoldii. Its smell is like rotting meat. Ginkgo biloba is sometimes called the maidenhair fern tree. It is the only living member of its class. Figure 6.3.9 Azolla may be small but it grows very rapidly. It quickly covers the surface of a pond or lake giving it a pinkish tinge. Figure 6.3.6 The lacy tree fern (Cyathea cooperi) is one of the tallest tree ferns. It is an Australian native plant commonly found in New South Wales. Figure 6.3.7 Cycads have separate male and female plants. The male plant produces pollen in cones. The female cone produces the seed and provides some protection for the seed as it develops. Figure 6.3.8 Classification 251 ]]></TextData></Page><Page><Page_no>268</Page_no><display_no>252</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Ginkgos have separate male and female trees. Male trees produce pollen in cones, and female trees produce seeds in fruit with a fleshy, smelly coat. Most conifers produce the male (pollen-bearing) and female (seed-bearing) cones on the same tree. Cypress, fir and pine belong to this class. Australian conifers include the hoop pine (Araucaria cunninghamii), Huon pine (Lagarastrobos franklinii) and Wollemi pine (Wollemia nobilis). The Wollemi pine is an ancient tree. It has been found in fossil records dating back 90$:$7f8nb0ap93eeBFgYgPa7x+Xzn7cxCxbX0aCcYGrzMoLkaNyf/w91nypX/QT0zeC7tQpwdxGfibRS
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S85ZbQGay+SSN8AHWXuk8LcnwRBtOQ==$:$l ready to be released. Then the mature cone breaks down releasing the seeds. The seeds are small with thin papery wings. The wings help the seeds to blow in the wind. Flowering plants produce seeds fully protected inside the female part of the flower, which is known as the ovary. Many of the flowers produced by flowering plants are used to attract pollinators such as bees, flies, moths, birds or bats. Grasses, with less showy flowers, are pollinated by wind. Tiny flowers Although this daisy looks like one flower, it is in fact hundreds of florets (small flowers) of two different types. Ray florets make up the parts that look like petals. Disc florets make up the central part. About 65 per cent of all flowering plants are pollinated by insects. Flowers have many characteristics that help them to attract insects, such as having bright colours, a perfume and nectar. Female cones are green, 6–12 cm long and 5–10 cm in diameter. They take about 18–20 months to mature. Then they break down to release the seeds. Male cones are 5–11 cm long and reddish-brown in colour when mature and ready for the pollen to be released. They are produced lower in the tree than the female cones. Figure 6.3.11 252 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>269</Page_no><display_no>253</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Nectar is a sugary liquid some insects use as food. When an insect visits a flower to collect the nectar, pollen sticks to its body. The insect then carries the pollen to the next flower. The shape of the flower limits the variety of insects that can pollinate it. For example, nectar at the base of a long tube-shaped flower can only be reached by insects with long mouthparts such as butterflies, moths and bees. Pearson science NSW 8 Unit 4.2 6.6 Fungi kingdom Mushrooms, toadstools and the bracket fungi shown in Figure 6.3.12 are fungi that are big enough to be easily seen. Other fungi, such as the yeast in Figure 6.3.13, are so small that they can only be seen through a microscope—they are microscopic. You may have seen fungi such as these bracket fungi on the trunks of dead trees. The blue-green mould growing on this orange is also a fungus. Figure 6.3.12 Shaking the pollen out Hibbertia is a common flower in coastal sand dunes. Its pollen is released by vibrations caused by the buzzing of certain bees. The blue banded bee and many Australian carpenter bees hold on to the plant and buzz, causing the plant to vibrate so the pollen is released. Yeast is a fungus used in the manufacture of beer and to make bread rise. This image shows yeast magnified ×2260. Figure 6.3.13 Fungi cannot make their own food, and therefore they must feed on other organisms. Fungi are the main cause of decay (or rotting) in fruit and vegetables. Fungi are decomposers responsible for breaking down wastes like $:$0KI2dlPTetUKPq237Ady1TCwNm865WvZ9LP09IzozGc//CrVFme5gasNi1R98T7Q564VWXEGFwG8
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Xt8=$:$r breaking down wastes and returning the nutrients they contain to the environment. Most bacteria rely on other organisms for their food. Examples are the decomposers and the bacteria that live inside your body. However, bacteria such as cyanobacteria or sulfur bacteria make their own food. Bacteria live in many different places, ranging in temperature from hot springs (Figure 6.3.17), where the temperature reaches 300°C, to the ice fields of Antarctica. A closer look at kingdoms Dogs, mosquitoes and jellyfish obviously belong to the animal kingdom, while wattles, tree ferns and pine trees are obviously plants. However, outward appearances aren’t always an accurate way of classifying living things. To accurately identify the kingdom an organism belongs to, you need to look through a microscope at what makes up the organism. You need to look at its cells. Cells All living things are made up of building blocks called cells. Cells are so small that they can only be seen using a microscope. All living things in the plant and animal kingdoms are made up of many cells. They are multicellular—multi means many. Some fungi are also multicellular but other fungi have only one cell making the entire living thing. These fungi are unicellular—uni means one. All living things in the monera and protist kingdoms are unicellular. Pearson science NSW 8 Unit 2.2 Pearson science NSW 8 Unit 2.3 The water in this bubbling geyser is very hot. Bacteria able to live in temperatures between 50°C and 60°C form a brown scum at the edge of the water. Figure 6.3.17 254 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>271</Page_no><display_no>255</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The cells of all organisms have parts in common: • cell membrane—the ‘skin’ that holds the cell together. • nucleus—the control centre of the cell. • cytoplasm—a watery, jelly-like mixture that contains many smaller parts. However, not all cells are the same. When cells are looked at using a microscope, differences can be seen. These differences are used to place the organisms in different kingdoms. How the organism feeds is another characteristic used to separate the kingdoms. The main characteristics of the five kingdoms are shown in Table 6.3.1. Prac2 p. 258 Table 6.3.1 Characteristics of the five kingdoms Kingdom Characteristics Examples Animal Animals are made up of many cells. Their cells have a membrane forming the boundary of the cell, a nucleus and cytoplasm inside the cell. Animals obtain their energy by feeding on other living things. nucleus cell membrane cell wall chloroplast containing chlorophyll cell membrane nucleus nucleus choloroplast nucleus cell wall cell membrane cell membrane cell wall Pelican, human, frog, spider, jellyfish Plant Plants are made up of many cells. Their cells have a cell wall outside the cell membrane. The cell wall helps support the plant and give it its shape. Many plant cells also contain tiny structures called chloroplasts in the $:$zsMMCEpCIt02kNYqYR/OK+0cfabZxnTUiI4U1nTyFrETJbDPreNxsblGjgPiLfS6FA+Uu5yAuPP3
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hyMlHg==$:$leus choloroplast nucleus cell wall cell membrane cell membrane cell wall Moulds, toadstools, mushrooms, yeast Protist Protists are single-celled organisms. Protist cells may be plant-like or animal-like. nucleus cell membrane cell wall chloroplast containing chlorophyll cell membrane nucleus nucleus choloroplast nucleus cell wall cell membrane cell membrane cell wall Protozoa, algae Monera Monerans are single-celled organisms. Their cells have a cell wall but do not have a clearly defined nucleus. All monerans are very simple and microscopic. nucleus cell membrane cell wall chloroplast containing chlorophyll cell membrane nucleus nucleus choloroplast nucleus cell wall cell membrane cell membrane cell wall Bacteria, cyanobacteria Classification 255 ]]></TextData></Page><Page><Page_no>272</Page_no><display_no>256</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review6.3 Remembering 1 Name the building blocks of all living things. 2 List the kingdoms with single-celled organisms. 3 Name the kingdom in which you will find all the organisms without a distinct nucleus in their cells. 4 Name the classes of seed-bearing plants. 5 Humans regularly eat plants as part of their diet. Usually they don’t eat the whole plant but just a part of it. Name two plants from which we eat their: a leaves b stalks c seeds d roots e fruit. Understanding 6 a Describe the characteristics that plants and fungi have in common. b Explain why plants and fungi are in different kingdoms. 7 Describe one problem and one benefit of fungi. 8 Describe the plant k$:$pr+qPIuHSab/96AtD8xJaf2bfeFm+7mm3QLe2D32Ha8KY8TxteCkzwztMwToNA1eKe7/H5/P6PVd
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gG8Kb8mvG8LJoaMArTwO5EHk+oTf8K+xVdmnjwkA93WCJ3I75vJsS24EC2IB$:$ side of a tree. Looking through the microscope, I could see many cells that all looked very much alike. There was a distinct cell wall. The cells were colourless. b The organism was seen when I looked at some water under a microscope. It was still very small when I had the microscope on its highest power. I could see that the organism was unicellular but I could not see a distinct nucleus. 13 Use the following descriptions to classify these plants. a It is less than one centimetre tall and when the leaves were examined under a microscope no vascular tissue could be seen. b Dark spots were visible on the back of the leaf and there was vascular tissue running along the middle of the leaf. c It is a tree over 20 m tall that has needle-like leaves and produces seeds in cones on its branches. Evaluating CCT 14 One organism was described as macroscopic. Another organism was described as microscopic. Propose what is the main difference between them. 15 The Wollemi pine was discovered in 1994. a Deduce the characteristics taxonomists would have used to decide which plant group it belonged to. b Justify your answer. 16 Plants that produce nectar are giving something to the insects that pollinate them. Propose why this relationship between plants and insects has come about. L 256 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>273</Page_no><display_no>257</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Creating CCT 17 Construct a mnemonic or rhyme to help you remember the divisions of the plant kingdom. Inquiring 1 Humans use many plants as a source of food. However there are many o$:$8QXI71ewuIa8hibaI7AHPllgsw8lO9REmSWEoIVR2u2WyF0SOWuDpQblqebl796ZyTctxV1z+pM4
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1cl4t2qvS7V7zZipNu6vdAQL6HVcxczdjbcTYA==$:$name given to an organism would be the name of the genus to which that organism belonged, followed by one descriptive name for the species—this way each living thing would only have two names. With this, binomial naming (also known as binomial nomenclature) was born. Latin was used as the language for naming because it was a language then understood by all well-educated people throughout Europe. Also, it was not a spoken language, and therefore the meanings of the words did not change. Words develop slightly different meanings and spellings over time when a language is spoken. This does not happen in Latin. Binomial nomenclature is now used internationally regardless of the language spoken in the country the organism or scientist comes from. The system has been used for plants since 1753, for animals since 1758, and for bacteria since 1980. Linneaus and Banks Linnaeus corresponded with the botanist Joseph Banks, who sailed to Australia with Captain Cook on the Endeavour in 1768. Also on board was Daniel Solander, one of Linnaeus’s students. Between them Banks and Solander collected more than 1000 species of plants new to science. The banksia is an Australian native plant named after Banks. ADDITIONAL 260 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>277</Page_no><display_no>261</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Scientific naming When scientists discover a n$:$xabKHyyoYnE9Q377uj+EasY/sl5xpKoKvZBUfU/XmZEoqQrkcd0qPK9VcpzA6r6/ziF1aLt6DKHd
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I4Jwada/bh3x5FRTpc1zYlbX8lU5IqUzwc/pAsw1BfIMj/O4+hf6$:$s with a capital letter. The second part tells you the species within that genus. This part of the name always starts with a lower case letter. When the names are typed, italics are used. When names are written, they are underlined. For example, Panthera leo, Panthera onca, Panthera pardus and Panthera tigris (Figure 6.4.4) all belong to the same genus. They all have the same first part to their name. If they are in the same genus then they must be fairly similar to each other. However, they are not all the same species. You can tell that because the second part of their name (their species name) is different. You are more likely to recognise the animals by their common names: lion, jaguar, leopard and tiger. 4.66.7 Panthera pardus (panther) Panthera tigris (tiger) Panthera onca (leopard) Panthera leo (lion) All these species belong to the same genus, Panthera. Figure 6.4.4 Levels of classification Kingdom is the first level of classification. The kingdoms are divided into smaller groups in which the organisms are more similar, as Figure 6.4.5 shows. The second level of classification is into phyla (singular phylum). In the plant kingdom the phyla are often called divisions. • Phyla and divisions are then divided into classes. • Classes are divided into orders. • Orders are divided into families. • Families are divided into genera (singular genus). • Genera are divided into species. Organismsbecomemorealike Organisms are classified first into broad groups— kingdoms. At each new level of classification, the organisms become more similar. Figure 6.4.5 Classification 261 ADDITIONAL ]]></TextData></Page><Page><Page_no>278</Page_no><display_no>262</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Moving down through the levels in the classification system, the groups become smaller in that they have fewer types of living things in them. Figure 6.4.6 shows how organisms become more similar as you move through the levels of classification. Organisms of the same species are most similar, but they are not identical. Look around at the people in your classroom or in the street. All the individuals in Figure 6.4.7 belong to the same specie$:$rXpKcCibqYXgID+jdFUbjtunsZ847itmmXSK8KhZjHgnMgD1DzqMOozbpUwT418l7MzCbrqqD+Tf
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g8xBZ+3WXQ==$:$mily. The classification also shows that according to scientists the eastern grey kangaroo and the common wallaroo are most alike. They also belong to the same genus. All humans belong to the one species but they are not all identical. Figure 6.4.7 Kingdom – Animal Phylum – Chordate Class – Mammal Order Primates Family – Hominidae Genus – HomoGenus – Gorilla A mnemonic is a way of helping you remember things. One way of trying to remember a list is to make a sentence with each word starting with the first letter of each word in the list. Problem Construct a mnemonic to remember the order of the groups in biological classification. Solution One possible mnemonic is shown below. Keep Placing Cake Orders For Good Students Kingdom Phylum Class Order Family Genus Species Practice Construct another mnemonic that would help you remember the order of the groups in biological classification. Constructing a mnemonic WORKED EXAMPLE Gorillas and humans are the two animals in this group that have most characteristics in common. Figure 6.4.6 ADDITIONAL 262 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>279</Page_no><display_no>263</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[ADDITIONAL Table 6.4.1 Common name Red kangaroo Eastern grey kangaroo Common wallaroo Kingdom Animal Animal Animal Phylum Chordate Chordate Chordate Class Mammal Mammal Mammal Order Diprotodon Diprotodon Diprotodon Family Macropod Macropod Macropod Genus Magaleia Macropus Macropus Description of species rufa giganteus robustus Scientific name Magaleia rufa Macropus giganteus Macropus robustus How similar or different other animals are can be seen in their classification. The red bellied snake belongs to the same phylum as the kangaroos and wall$:$1k9L7tjuwSBpUSe6pY8GBfpVPiw/fZqzfg4jfSg7hXI/1MZXxihjWYTSRe3gHYp9easVl2uQZ1vZ
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euj2ZhJPRv7io4fBYfyG$:$hown in Figure 6.4.9 • things that breathe and reproduce. This group includes all plants and animals except humans. • humans. IndIgenous classIfIcatIon Indigenous people all over the world have complex and sophisticated classifications of plants and animals, but they do not look like the system used by Western science. Indigenous classifications help the people of a tribe or local area to communicate about the plants and animals that are important to them. Bush tucker Figure 6.4.8 ADDITIONAL The Yolngu people of Arnhem Land classify fire as ‘something that could move itself’. Figure 6.4.9 264 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>281</Page_no><display_no>265</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The classification of the Yolngu is shown in Figure 6.4.12. It is a lot simpler. There are no specific names for the different finches: they are all lidjildji. They only give specific names to things that are of special use or significance. Figure 6.4.12 The Yolngu have a simple classification of the finches of northern Australia. Thing that has life Lidjildji (finches) (All finches have the same name) Warrakan Thing that breathes and reproduces revIew 1 Specify what sorts of animals are included in the following terms. a guya b warrakan 2 State the Yolngu name for: L a plants with woody stems b snakes and lizards. 3 Explain why the Yolngu people do not have names for all the different birds. 4 Identify issues that could arise if Indigenous Australians from one area were discussing hunting for food with a tribe from a different area. 5 a Propose whether the five kingdom biological classification of living things would be of use to Indigenous Australians. b Justify your answer. 6 Deduce reasons for there being many different Indigenous classification systems for living things in Australia. 7 The Yolngu peopl$:$/z7X/VhTXqtsSDCUzqyoM7Z2cG1WqSaOE8TeNo5zHdjf37IBVlVIYBs+nf8uhYKIa3sCb5BqXl34
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v63P2aAj6IPMQWft1l0=$:$illidae (Finches) Genus Poephila Poephila acuticauda Long-tailed finch Poephila bichenovii Double-barred finch Poephila personata Masked finch Figure 6.4.11 Scientific classification of finches The Yolngu group animals according to how they move. Birds and bats are in the same group—the warrakan butthunamirr—because they can both fly. Biological classification uses differences between birds and bats to place them in separate groups at the level of phylum. Galahs are named Eolophus roseicapillus and the lesser long-eared bat is named Nyctophilus geoffroyi. Figure 6.4.10 Classification 265 ADDITIONAL ]]></TextData></Page><Page><Page_no>282</Page_no><display_no>266</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review6.4 Remembering 1 State the first level in biological classification of living things. 2 List these levels of classification into order from the one in which there is the greatest number of different types of organisms to the level in which the organisms are most similar. family genus class phylum 3 Name the sci$:$j7EXI7bkhCpAtgnYEJCc7Czs836v3CupDJA6TGGjr3SmIuqtbdkwuYWRTO08/S1VREg0796OvlzJ
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qK6VjFuTjYSa/5zQiuiDzEFn7dZd$:$es should be written by rewriting the names below correctly. In each example, the genus and species are in the correct order. a Pan Troglodytes b homo sapiens c banksia Robur Analysing 8 Compare a group of organisms that all belong to the same phylum with a group of organisms that all belong to the same family. 9 As people explore new environments, they find new organisms that have to be described and named. Discuss the advantages of having the binomial system of classification compared to the system used before Linnaeus. Evaluating CCT 10 The eastern pygmy-possum (Cerartetus nanus), the common brush-tailed possum (Trichosurus vulpec), the mountain pygmy-possum (Barramysula parvus) and the short-eared possum (Trichosurus caninus) are all possums found in New South Wales. a Identify the possums that are most similar. b Explain why you made that choice. c Propose a reason for them all being commonly known as possums when biologists classify them differently. 11 Refer to the following plant names: • Eucalyptus robusta • Grevillea banksii • Metrosideros robusta • Grevillea ericifolia • Eucalyptus banksii a i Identify which of the listed organisms would be most closely related to Grevillea robusta. ii Justify your response. b i Select other species in the list that are related to each other. ii Explain your selection. c i State how many species are represented in this list. ii Justify your response. d i State how many different genera (plural of genus) are represented in the list. ii Justify your response. ADDITIONAL 266 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>283</Page_no><display_no>267</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[12 The magpie with the biological name Pica pica (Figure 6.4.13) is a common bird in Europe. Cracticus tibicen (Figure 6.4.14) is a familiar Australian bird and is also commonly known as the magpie. Biologists do not consider these two birds to be similar. Propose reasons for the European magpie and the Australian magpie both having the same common name. 13 Four organisms A, B, C and D all belong to the same kingdom. A and D belong to the same class. A and C belong to the same genus. B and C belong to the same order. a Deduce which two organisms are most alike. b Use this information to answer the question: ‘Do organisms A and B belong to the same order?’ c Justify your decision. Creating CCT 14 Construct a concept map showing the characteristics of the five kingdoms. Inquiring 1 A classification system for plants used by Indigenous Australians was into ‘plants used for medicine’ and ‘plants used for food’. Use library and internet resources to discover more about the use of plants for medicine and discuss the idea that other cultures in other places and at other ti$:$sGADs9EVC9aLI1c1zHoDo/IUrU1glxBpGyHQVNnxe1k0s9LCYfRJB2yO9xSJ/V8BEAMmogm727ee
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Hmfrkxkp/XZOL8wPtD/mcY+lBMOkocrF93iqot0Uig==$:$the school. Include in your presentation the most surprising thing that you learned about the way that the local Indigenous community classified living things. 3 Talk to people from the Indigenous population in your local area to learn some of their stories that describe the special relationship that the Indigenous people have with the land and the native plants and animals. ICT The European magpie (Pica pica) Figure 6.4.13 The Australian magpie (Cracticus tibicen) Figure 6.4.14 ADDITIONAL Classification 267 ]]></TextData></Page><Page><Page_no>284</Page_no><display_no>268</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations6.4 The names I know Purpose To explore ways in which classification systems could have evolved. Materials • paper • pencil Procedure 1 Make a list of the living things that are regularly part of your life. 2 If you know the name, use it—for example dog, or apple. If you do not know specific names, use group names such as tree or bug. 3 Share your list with others and combine all the lists into one. 4 Think of ways in which you could group the things you have on your list. For example, you could have pets or food. 5 If you have a very long list in some groups, subdivide it into smaller groups by making a second level of classification. 1 6 Construct a key for the items in your lists. Go only as far as you think is useful. You do not have to separate out each item. Practical review 1 a Identify which type of classification your key most resembled—biological classification, or one more like that used by Yolngu people. b Explain why this was the case. 2 a Compare the items for which you had specific names and those for which you had group names. b State which of these would be more important to you in terms of survival. 3 a Compare the list you started with and the final list used for the classification. b Estimate how much of your list was the same as the lists from the others in your group. 4 a Identify the groups where there was the greatest amount of overlap. b Explain why there was so much overlap. 5 a Identify the groups where there was most difference. b Explain why there was so much difference. Classifying weather Purpose To compare calendars. Materials • pen • paper Procedure Part A 1 Analyse the information presented in calendars from two Indigenous groups: the Wardaman people of Northern Territory and the Brambuk people of Victoria (Figure 6.4.15). 2 2 Compare the calendars with the temperat$:$gzW+tESkCM+x0mKzW7Xqn3OgDHWK6gnEsnDoK+/SlWwlu2DsqW6HyZK0Ke5TJDMsu58YaPFINgZM
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tMg=$:$ingle muscular foot d Has a nerve cord Understanding 7 Define the term classification. L 8 Explain why the products in supermarkets are not arranged in alphabetical order. 9 Explain how classification is used in: a clothing shops b online music stores. 10 Explain why characteristics such as hair length or style, or the presence of facial hair, would not make a strong key. 11 Describe the characteristics that cause plants and animals to be placed in separate kingdoms. 12 Gather information from Unit 6.3 about the protists and explain why this kingdom could be called the ‘kingdom of misfits’. Applying 13 The two animals in Figure 6.5.1 look very different. Refer to Table 6.3.1 on page 255 to explain why they are both classified as animals. 14 Identify characteristics that could be used in a key to identify the creatures in Figure 6.5.2. Figure 6.5.2 Figure 6.5.1 270 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>287</Page_no><display_no>271</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[15 Identify t$:$khO+S89T2PHNQ2lgTW6O5BSXDXQdzSwd4AyTpkifsyT5v3iyANqJbuN5O8Mcu05Ee0x6avSGsq8J
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Ni+g8T506XZdfGPl0By/+F63CAN8STDxfSt9X/aluC+E$:$a thin ‘skin’. Flagella are visible attached to each cell. A nucleus is visible within each cell. b Large organism standing about two metres tall. A soft brown hair covers its body. It had a pouch- like structure on the front of the body. At times a small head appeared out of the pouch. c Small green leaves are arranged in a spiral around something that looks like a stem but it has no vascular tissue. This organism is about one centimetre tall. It was found in the shade behind a rock. 18 Analyse the key in Figure 6.5.3 to identify its strengths and weaknesses. Evaluating CCT 19 a Determine whether you can or cannot answer the questions on page 227 at the start of this chapter. b Assess how well you understand the material presented in this chapter. Creating CCT 20 Apply your knowledge of keys to construct a strong key for the creatures shown in Figure 6.5.2. 21 Use the following ten key words to construct a visual summary of the information in this chapter. kingdom species classification taxonomy dichotomous key plants animals protists monera fungi Writing tools Plastic case Black lead PencilBall point Thick Thin CD/DVD marker pen Permanent marker Coloured lead Felt tip Roller tip Coloured pencil Wood on the outside Figure 6.5.3 6.8 Classification 271 ]]></TextData></Page><Page><Page_no>288</Page_no><display_no>272</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[$:$+QDi6dObSbkk8gNIAtmYEKtHEKoLOZvr0y+fKqu+f86DJ2agn4RtVvE6BRrn2WvWOuig5+djeKJi
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$:$ristic did Jo use to create the groups? CCT A Number of legs B Number of pairs of wings C Number of body parts D Other characteristic Q2 Which characteristic did Kai use to create the groups? CCT A Number of legs B Number of pairs of wings C Number of body parts D Other characteristic Q3 Students created this key for their group. CCT 1 a Male. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Go to 2 b Female . . . . . . . . . . . . . . . . . . . . . . . . . . . . Go to 5 2 a Straight hair . . . . . . . . . . . . . . . . . . . . . Go to 3 b Curly hair . . . . . . . . . . . . . . . . . . . . . . . . . Go to 4 3 a Can roll tongue. . . . . . . . . . . . . . . . . . Mark b Cannot roll tongue . . . . . . . . . . . . . Yasu 4 a Brown eyes . . . . . . . . . . . . . . . . . . . . . . Hans b Grey eyes. . . . . . . . . . . . . . . . . . . . . . . . . Jack 5 a Straight hair. . . . . . . . . . . . . . . . . . . . . . Jane b Curly hair . . . . . . . . . . . . . . . . . . . . . . . . . Mai How many people in the group have straight hair? A 1 B 2 C 3 D 4 Q4 The aliens below belong to three different family groups. Which two aliens belong to the same family? A 1 and 5 B 2 and 3 C 4 and 6 D 5 and 8 Q5 Which alien belongs to the same family as alien 9? CCT A 8 B 6 C 7 D 3 CCT 1 2 3 4 5 6 7 8 9 272 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>289</Page_no><display_no>273</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit 6.1 L Classification: the process of putting things into groups Dichotomous key: a key with two choices at each stage Pest species: an animal species that causes problems and is not wanted in an area Taxonomist: a scientist who specialises in grouping and naming things Taxonomy: the science of grouping and naming things Weed: a group name for any plant growing where it is not wanted Unit 6.2 L Agnatha: jawless fish with an internal skeleton made of cartilage; examples are hagfish and lampreys Amphibians: chordates that live both in and out of water Animal: one of the five kingdoms of living things; multicellular organisms with cells that have a membrane as the outer layer and a distinct nucleus Annelids: phylum of the animal kingdom consisting of the segmented worms; for example, an earthworm Arthropods: animals with an exoskeleton and jointed limbs; examples are crabs and insects Aves: animals with feathers covering their body; lay hard-shelled eggs and are endothermic Cartilage: flexible material from which the skeletons of Agnatha and Chondrichthyes are made Chondrichthyes: fish with proper jaws and teeth, a skeleton made of cartilage and fins on the sides of their bodies as well as along their backs; examples are sharks and rays Chordates: animals with a nerve cord running down their backs, and an endoskeleton Cnidarians: animals with radial symmetry, one body opening and stinging cells; examples are jellyfish, sea anemones and coral polyps Amphibians Cnidarians Glossary Echinoderms: radially symmetrical animals, most of which have spiny skin; examples are starfish, brittlestars, sea urchins and sea cucumbers Ectothermic: describes animals with a body temperature that varies with the temperature of their surroundings Endoskeleton: a skeleton inside the body Endothermic: describes animals with a body temperature controlled internally Exoskeleton: a skeleton on the outside the body Invertebrates: animals without backbones Kingdom: the first level of classification Mammals: a class that includes all the animals that have a body cov$:$aV3fbTW6iOYohOVzcxcbpOR6ekVIgMgdVoeDDIQAFQUTh4hhOugIxIeHiMfFzuUi3VZBrJyirzmG
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LENH8Ntbcy2u7c8ZtTjYqvszj7JdPny+heU=$:$d ‘weight’ L • describe what happens when magnets are brought close together • investigate how magnets and electromagnets are used CCT • describe ways objects become charged • describe how charged objects behave when brought close to each other • investigate situations where the effects of electrostatic forces can be observed such as lightning strikes CCT ADDITIONAL • investigate specific forces in terms of size and direction • research ideas about Earth’s magnetic field and its effects. After completing this chapter students should be able to: Have you ever wondered... • why cars are designed with crumple zones? • why competitive swimmers wear a cap or shave their head for a race? • why clothes crackle after being tumble dried? 276 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>293</Page_no><display_no>277</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[7.1 Forces act on you all the time. If you surf, you can feel many forces pushing and pulling you in different directions. Gravity always pulls yo$:$gMQJjWR2rx5wONXLR9La6druZZlrE782ekJJ2jBB5heaEusqez2Iz7TVaGeeHSxJq6y1/f86/FBO
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1Qj02yxhHVBv9Oeuyqo0g+Kj1QzSLb0zg3ar2Z2p5LD1GqdYO66o4qgovYUoVw==$:$ the lid. 3 Observe what happens to the marble when you push the skateboard/truck forwards; stop it, or push it around a corner. Record this… Describe what happened to the marble in each case. Explain why you think this happened. Marathon impacts It is estimated that in the course of a typical marathon, a runner will take around 25 000 steps and so their feet will experience around 25000 collisions with the ground! 280 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>297</Page_no><display_no>281</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Car safety features When a car stops suddenly, its passengers continue to move forwards until they hit something that stops them. This is inertia at work. If the windscreen, dashboard or steering column stops them then they will usually hit the object head-first. This concentrates impact forces on their brain and they can be seriously injured or killed. Crash testing is used to assist the development of safer cars and to inform consumers of the safety rating of new cars on the market. Figure 7.1.10 shows what happens to crash test dummies the instant after a car hits a wall at 56 km/h. The ANCAP (Australasian New Car Assessment Program) uses a system of star ratings of 1 to 5 stars to indicate how safe a car will be in an accident. Cushioning of the sole of a shoe absorbs impact from running forces. A raised arch prevents the foot from rolling inwards. Figure 7.1.9 The simplest way of preventing serious injury is to wear a seatbelt. A seatbelt holds you in place during a collision and minimises the impact forces on you by spreading them across y$:$r339ufiCZsOg5Q9fHFywLwTOQVGsUECylS3N3o66L1c2rEQUMl0UZAOud02HtzWFgWo7qcCyiZrb
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V0ApEooOyRkE0zf12jvu$:$the motion of the object changes. This means that the object may start moving, stop moving, speed up, slow down, change direction or even change its shape. • Use a search engine to find images of objects that are involved in each of the six types of changes of motion listed above, OR use computer animation to show objects undergoing each type of change in motion. • Add labelled arrows to each of your images or animations to show where you think a force is acting. • Identify the direction of the unbalanced force that acts in each case and use this to explain its change in motion. Present your images or animation digitally. ICT ADDITIONAL 2 Search the internet to find the size (measured in newtons) and direction of specific forces. You could choose something like: • the weight of an 80 kg adult • the weight of a 2 tonne car • the weight of a large commercial jet liner such as the Airbus A380 • the force required to open a door • typical friction forces of car or bike tyres moving across different surfaces such as bitumen, concrete or grass • the typical force required to walk • the force of a dog bite • the force on a car colliding at 60 km/h with a wall. Select five specific forces and present the information you find as a diagram or image with labelled arrows added to them to show the direction the force(s) is/are acting. ICT ADDITIONAL 284 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>301</Page_no><display_no>285</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations7.1 Looking at forces Forces act all around you, all of the time. Whenever the shape or motion of an object changes, you know that an unbalanced force has acted. Purpose To observe a range of forces in action. Materials • lump of Plasticine • textbook • table tennis ball • tennis ball • balloon • plastic cup • woollen fabric • pencil case • magnet • ruler • paper clip • bucket • plastic straw Procedure 1 Copy the table into your workbook. 2 Complete each of the tasks in the table, recording your observations as you go. 1 Results Record all your observations in the appropriate columns of your table. Practical review 1 A force was acting in each task. Explain how you knew. 2 List any objects that changed shape as a result of the force. 3 S$:$L9UvSyEwuV2Pxv/tWhpkzNZMUD4HPFTSiRQ12hzDn91i2CXoafT69Vj23CNTYrka/s8cHFrRdSwQ
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+5RScDM0uxAPS9gpjUqajP/6urlE63DH2hTGEuuGuka56R36bIh+$:$ey from the top of the ramp, and watch the motion of dummy A carefully (or record its motion) as it hits the brick. 5 Repeat the test three times and record your observations. Part 2: Collision between two vehicles 6 Join with another group. Remove the brick and place one trolley and dummy B in its place. 7 Release dummy A from the top of the ramp and record what happens to dummies A and B when the trolleys collide. 8 Repeat this test three times. Practical review 1 Part 1: Collision with a barrier a Describe changes in the motion of dummy A on impact. b Explain these changes in terms of inertia. c List any safety features that would protect dummy A in this impact. 2 Part 2: Collision between two vehicles a Describe changes in the motion of dummy A on impact. b Explain these changes in terms of inertia. c List any safety features that would protect dummy B in this impact. 3 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. 286 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>303</Page_no><display_no>287</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[STUDENT DESIGN STUDENT DESIGN A force-measuring device Purpose To construct a device that can measure the size of a force. Materials Students could select materials such as elastic bands, springs, or other elastic material in their design. Figure 7.1.15 could give some ideas. 3 Figure 7.1.15 SAfETy A Risk Assessment is required for this investigation. 2 Write your procedure in your workbook. 3 Before you start any practical work, assess your procedure. Assess any risks that your procedure might involve and what you might do to minimise those risks. Show your teacher your procedure and your assessment of its risks. If they approve, then collect all the required materials and start work. Hints Once you have assembled your device, you will need to calibrate it. This means that you need to make a scale that links the extension or compression of your device with a reading of force measured in newtons (N). To calibrate your device, you need to know that the reading of a hanging 100 g mass corresponds to a force of 1 newton. Results In your workbook, draw a diagram of your force- measuring device. Practical review 1 Explain what is meant by the term calibration. 2 Assess the effectiveness of your design for measuring forces. 3 Propose any improvements you could make to your design. Marble run Purpose To build a structure that will apply different forces to a marble. Materials Students could select materials such as: • elastic bands • wooden ramps • springs • balloons • cardboard$:$a2bSnL4O2fMw2/KJvCaDi43MKY54fyS4OmQQ/rnsxg3ex4Cim0SWt13dCL8bE2fkvTFYO9y60QBq
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Jzc50caQTo5IZ2mTnQ==$:$he required materials and start work. Results Record your observations about the journey of the marble. Practical review 1 Assess how effective your design was in making the marble speed up, slow down, change direction and finally stop. 2 Propose any improvements you could make to your design. Procedure 1 Design a device that will stretch or compress when acted on by a force. Forces 287 ]]></TextData></Page><Page><Page_no>304</Page_no><display_no>288</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Things that are moving continue to do so unless a force makes them stop. The force that makes most m$:$ETH0Byuaf+7z2tj56/ZOLz9jOXBKWHo2tQChguyzpgQ1OuIwc+vow73v/KS8cIhcoEZmPoVGfkOZ
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FFxWphNI6AM4+n/tnL1QkJPT+f1tM4K+RciGrcjFZrNCsRCNdHTZQ9UaLvTLGvJVKz1Vf+U=$:$own. Friction can be a problem. It causes machines with moving parts to heat up, which wastes energy. Friction—a contact force7.2 Warming up Collect this … • block of wood • piece of sandpaper Do this … 1 Rub your hands together as quickly as you can for a minute. How do they feel? science fun 2 Now rub a piece of sandpaper back and forth over a piece of wood for a couple of minutes. Feel the surface of the wood. Record this … Describe what happened in each case. Explain why you think these observations happened. 288 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>305</Page_no><display_no>289</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[What is friction? If you roll a soccer ball along a patch of grass, then it will slow down and eventually stop. The force that slows it down is friction. Friction occurs whenever one object tries to move over another. Because it occurs between surfaces in contact, friction is called a contact force. Friction acts in an opposite direction to motion, as shown in Figure 7.2.1. friction motion Figure 7.2.1 Friction always acts in the opposite direction to motion. Two sheets of sandpaper will appear to ‘stick’ when you try to slide them over each other. This is because the grit on one sheet grabs and catches bumps on the other. This causes friction, and collisions between these bumps create heat. All surfaces have bumps on them, even ‘smooth’ materials such as glass or steel. Figure 7.2.2 shows the microscopic bumps on the ‘smooth’ surface$:$f/VlV9coWBk6KnqvwAtl1bT3coK/O36NdcZiS2kkx6kXxpVFKGlLx+vw8OdRALMlI4EAqkaYgTuD
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sTkdmRtKpyYWlqaIjqvFlA==$:$hed together. The greater the weight of a sliding object, the greater the force of friction, as shown in Figure 7.2.4. The puck used in ice hockey will travel long and fast along the ice unless it is blocked. This is because of the low friction between the ice and the puck. Figure 7.2.3 Prac1 p. 294 smaller friction force (easier to push) larger friction force (harder to push) Greater friction exists between the heavier box and the floor than between the lighter box and the floor. This makes the heavier box harder to move. Figure 7.2.4 Forces 289 ]]></TextData></Page><Page><Page_no>306</Page_no><display_no>290</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Useful friction When you walk, you push your foot backwards against the ground. The force of friction acts in the opposite direction to push you forwards. For this to happen, there must be enough traction, or grip, between your feet and the ground, otherwise you will slip. This is shown in Figure 7.2.5. Without friction you could not walk, run, ride a bike or travel in a car, and you could not pick things up (Figure 7.2.6). You push back onto the ground as you walk. Due to friction, your body is pushed forwards. Figure 7.2.5 Friction enables us to walk. Figure 7.2.6 The ridges and grooves seen in your fingerprints increase the friction between your fingers and the objects you grasp. Unwanted friction You rely on friction in your daily life, but it also has some unwanted effects. Moving parts, such as those $:$a6aSR2FxbuH4oescEZW/kpL4g0mR9QgX5fjMyb6lg35f7hFtjDBE6hvRpPFggVOrzGC5wxDZ39hz
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$:$the car did not have a radiator. A car radiator releases excess heat to the air that passes through it as the car drives along. Friction between an object and the air around it slows its motion. This type friction is called air resistance, or drag. A wind tunnel, such as that shown in Figure 7.2.7, can test how well an object cuts through the air. Drag occurs at the front of an object where air bunches up as it moves forward, and also behind it, where there is a space needing to be filled. Figure 7.2.7 290 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>307</Page_no><display_no>291</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Reducing friction Reducing friction makes machines more efficient, cheaper to run and longer lasting. Friction can be reduced by a number of different methods. Some are shown in Figure 7.2.8. Pearson science NSW 8 Unit 5.2 Figure 7.2.8 There are a number of ways friction can be reduced. Removalists use trolleys to shift refrigerators because rolling surfaces produce less friction than sliding surfaces. Skateboards and rollerblades have ball bearings inserted into the hub of their wheels, allowing them roll more freely over the axle. You may have slipped on spilt grease or oil at home. These substances are called lubricants. By adding grease to ball bearings, or putting oil into a car, we reduce the friction between moving parts. Polishing a surfboard helps to make its surface smoother and will reduce friction. An effective way to reduce friction is to stop moving parts being in contact with each other. A $:$tTGXxNRZ8zontcDEJWv1twNy8p1pW4KFmbjiAAGMRe3ne8z/Q3kW6pU4v/xH9zcnat4uJq9IuDEz
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myKmXaZaHk0a2+m1YpeLsICjhMEtZad+$:$s skin. The shark’s scales reduce churning of the water as the shark moves, and allow it to glide more smoothly as it seeks its prey. Swimsuit friction Swimmers have always tried to reduce their friction with the water. Men shave their heads, legs and chests and swimmers often wear full- body swimsuits. In 2009, swimmers competing in the World Titles in Rome were allowed to wear hi-tech polyurethane swimsuits, resulting in 43 new world records. These suits are now banned in competition. Forces 291 ]]></TextData></Page><Page><Page_no>308</Page_no><display_no>292</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review7.2 Remembering 1 State three everyday activities you couldn’t do without friction. 2 State whether the following are true or false. a Friction acts in the same direction as an object’s motion. b The greater the weight of the sliding object, the smaller the force of friction it experiences. c Friction makes a machine more efficient. Understanding 3 Identify the surfaces that are in contact when friction acts: a when you kick a football b when you swim at the beach c as you walk down the street d as two people push a broken-down car. 4 In your own words, explain why friction exists. 5 Without friction, you could not pick up an apple. Explain why. 6 Explain why a car needs a radiator to operate effectively. 7 Explain why it is easier to push a toy chest along the floor when it is empty than when it is full. 8 Explain why ball bearings are used within the hubs of skateboard wheels. 9 Your grandmother$:$npKXE3sX/07rgcN9VnAvljfpOFLYsRY87H7nfM6hh1qSS4N6hwh5DxHVKiZYdOgTciXYR6GQr9+2
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ABt3WWSN1/xNEWAJXUgHgNdma8tkdM48vC9q9u9IDOiDzEFn7dZd$:$more heat. Analysing 12 Figure 7.2.9 shows an ice-skater performing a routine on ice. a Compare the level of friction that would be present on the ice and on a footpath. b Discuss how this difference allows the ice-skater to move differently on the ice. c The base of an ice skate is a narrow blade. Explain how this shape helps to lessen friction. 13 Analyse the following and rate them in order from those that would experience the most friction to those that would experience the least. • A couch being dragged across carpet • A waxed pair of skis travelling on snow • An ice-hockey puck hit across the ice • A child’s tricycle being pulled along the footpath Figure 7.2.9 292 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>309</Page_no><display_no>293</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Evaluating CCT 14 A minibus is travelling along a flat road. Use Figure 7.2.10 to answer the questions below. a Name two sources of friction that are acting on the vehicle. b State the direction in which these forces act. c Describe what the driver should do to maintain the speed of the minibus. d The surfboard is now removed from the roof- rack. i Explain whether the friction acting on the minibus would increase or decrease. ii Justify your answer. e Predict what would happen if the tyres on the minibus were not properly inflated. Use friction to justify your answer. 15 The blades of an electric mixer are hot after beating some cream. Justify why this has happened in terms of friction. 16 Weightlifters rub chalk onto their hands before attempting a lift. The chalk absorbs any sweat on the weightlifter’s palms. a Propose why weightlifters use this chalk. b Predict what could happen if they use too much chalk on their hands. Creating CCT 17 Imagine that you wake up one morning and the force of friction no longer exists. Construct a role-play, story or a flow chart in which you describe what happens when you attempt five everyday tasks, such as getting dressed, brushing your teeth, cooking and eating your breakfast, getting to school, and sitting in class. Figure 7.2.10 Inquiring 1 Some animals move through water as they swim, some animals move through air as they fly and some animals move over la$:$Pmfwe7oL4yQk3VO4w02d3wCaDfJrKq5f8jFmkWqvR+V0RSyuP/TqpikmJiPHyEoHOhDbSFJxUOPL
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JaVdJjm6i6ddIYLIdqzj$:$ted or not. N N Object moving Friction force measured (N) Average friction (N) Trial 1 Trial 2 Trial 3 Wooden block Wooden block + 200g Wooden block + 400g Wooden block + 600g Wooden block + 800g Wooden block + 1000g 294 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>311</Page_no><display_no>295</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Reducing friction Purpose To reduce the force of friction between a block of wood and a wooden ramp. Hypothesis Which materials do you think will have the greatest and the least friction when a wooden block is slid across them? Rank the materials you are testing in order from the one you think will produce the least friction to the one that produces the greatest friction when a block slides along it. Before you go any further with this investigation, write your ranking in your workbook. Materials • wooden block • wooden ramp • various materials to place on the ramp, such as: – linoleum square – carpet square – sandpaper – waxed paper – other materials as approved by your teacher • protractor • 3 pieces of dowel Procedure 1 Copy the table in the Results section into your workbook. 2 In the second column of your results table, enter the details of each surface you are testing. With permission, you may also test the block on 2 tablespoons of cooking oil. 3 Place the wooden block on a marked position near the end of a plank of wood. 4 Slowly lift the end of the plank that the block is on, holding the other end of the plank on the benchtop as shown in Figure 7.2.13. 2 wooden block ramp material to be tested 90 protractor benchtop Figure 7.2.13 5 Use the protractor to measure the angle at which the block first starts to slide down the plank. 6 Repeat the test using the wooden dowels as rollers, and then test each surface you have available. Results 1 Record your results in the table. Experiment number Set-up of equipment Angle at which block starts to slide down ramp 1 Wooden block on ramp 2 Wooden block placed on dowel rollers on ramp 2 Construct a bar or column graph that co$:$0tPB+mocKzV2J/2vPXzvxibWugy5niX5IwUW4oB/wU73EF1/RqKtbzwqvUCvECv4Ltiq0rAkh8uD
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uzvPxpvezZb8aPWus1YTz95FwLY/R07t99SvQCI=$:$ height, you’d be fairly sure that the stone would hit the ground first. For many centuries, this caused people to believe that heavier things fell faster than lighter ones. The Italian scientist Galileo Galilei (1564–1642) performed experiments with falling objects. He realised that the reason some things fell faster was not because they weighed more, but because they had a smaller surface area than other things. Air is pushed out of the way as an object falls. An object with a small surface area experiences less air resistance as it cuts through the air compared to an object with a larger surface area. If there was no air, any two objects, even a feather and a hammer, would fall at the same rate. This is shown in Figure 7.3.5. 1 1 2 3 4 2 3 4 The feather is slowed by the effect of air resistance as it falls. In air In a vacuum (no air) The hammer and feather fall at the same rate. Falling bodies As predicted by Galileo, a feather and a hammer will fall at the same rate if dropped in a vacuum. Figure 7.3.5 Real or legend? At the time of Galileo Galilei, people believed that heavier objects fell faster than lighter objects. Galileo believed that all objects were affected equally by gravity, but fell at different rates due to differences in the air resistance affecting each. Legend has it that Galileo dropped two balls made from the same material but of different masses from the Leaning Tower of Pisa to prove his point. Forces 299 ]]></TextData></Page><Page><Page_no>316</Page_no><display_no>300</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[A leaf has a greater surface area than a stone of the same mass. Hence it experiences a greater force of friction (air resistance) when falling in air. This slows its motion and causes it to flutter as it falls (Figure 7.3.6). Terminal velocity As an object’s speed increases, its air resistance also increases. This means that the air resistance on a falling object increases as it falls. Eventually, the air resistance acting on the object equals its weight force. When this happens, the forces acting on the object are balanced and the object then falls at a constant speed. This speed is called$:$2Q30xZwQSjl732jbYBk8Y7q6JrTHbo8gxLDgF3FKbgTEKS9o91uwLXJE5d93ppmPwPFp5GdMlDrB
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5y2Eh73ivpivtQdIVED4$:$y Galileo. Figure 7.3.6 A leaf flutters as it falls, because it has a relatively large surface area and experiences more air resistance than other more compact objects. Air resistance at high speed Weight (force due to gravity) Air resistance Weight (force due to gravity) Speeding up Terminal velocity Air resistance at high speed when parachute opens Weight (force due to gravity) Slowing down Initially, after jumping out of an aircraft, the skydiver speeds up because the air resistance is small. Once the parachute is opened, the force of air resistance is greater than gravity and the skydiver slows down. Air resistance increases with increasing speed, until this balances the force of gravity. The skydiver now falls at a constant speed, known as terminal velocity. The motion of a skydiver depends upon the relative sizes of the forces of air resistance and weight. Figure 7.3.7 7.4 7.5 7.6Prac2 p. 304 Prac1 p. 303 300 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>317</Page_no><display_no>301</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review7.3 Remembering 1 Recall gravity by selecting the correct term to complete the following sentences. a Gravity is a contact/non-contact force. b Gravity pulls/pushes objects towards the Earth. c All objects naturally attract/repel each other. d Objects of the same mass fall at different speeds due to their weight/surface area. 2 State the unit used to measure mass. 3 State the unit used to measure weight. 4 Name the force that slows down an object as it falls. Understanding 5 Explain what a force field is, giving two examples. 6 The lines in Figure 7.3.8 represent Earth’s gravitational field. field lines Figure 7.3.8 a Describe what happens to an object that is located in the region of this field. b Describe what happens to the strength of this gravitational field as an object moves further away from Earth. c Explain why gravity is called a non-contact force. 7 Two forces act on a skydiver falling towards Earth. a Name these two forces. b Use a force diagram to help you explain at what stage of the fall the skydiver is accelerating, or speeding up, as they travel towards Earth. c Eventually the two forces are balanced. Explain how this affects the skydiver and state what this motion is called. Analysing 8 Gravity pulls people downwards regardless of where they are on Earth. Discuss how this is possible. Use a diagram to assist in your response. 9 a Compare how your body would feel when walking on the Moon compared to walking on $:$OX2yKlHONd5GovRwox1FoEzoLYjUgECNPdsR9opsfblL2JVZkr00pQQ5or1ZcqFkbg5FBBIpdr5F
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oynYHMR2$:$rop zone’ to test how fast each object falls. 5 Drop the 50g mass and another item from the height marked on the wall as shown in Figure 7.3.10. Figure 7.3.10 Blu Tack marker foam or rubber mat 2 metre drop zone 1 SAfETy be careful not to drop objects where they could fall on someone. 6 Record whether the object landed at about the same time, slower or faster than the 50g mass. Repeat the test if you are unsure. 7 Repeat, using the 50g mass and every object to be tested, and record your results. 8 Drop the 50g mass and the sheet of A4 paper (held horizontally) and record your result. 9 Crumple the sheet of paper into a loose ball and repeat the test. 10 Finally, scrunch the loose ball into the tightest ball you can and do the test again. Results Record all your masses, predictions and measurements in your table. Practical review 1 Assess how accurate your predictions were. 2 State whether most objects fell at the same rate as the 50 g mass, or faster, or slower. 3 a State which object fell the slowest. b Propose a reason why this was the slowest. 4 a Name the objects that fell faster than the 50 g mass. b Propose reasons why. 5 Propose a reason why the 50 g mass was used in every experiment. 6 a Summarise how the shape of the sheet of paper changed how it fell. b Explain why. 7 Draw a conclusion for this activity. Falling object Mass (g) My predictions Landed Will fall the same/faster/ slower than the 50g mass about the same time as 50g mass before the 50g mass after the 50g mass Forces 303 ]]></TextData></Page><Page><Page_no>320</Page_no><display_no>304</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations STUDENT DESIGN 7.3 Robocopter investigation A robocopter is a paper construction that spins as it falls when it is dropped from a height. Purpose To make a robocopter and then determine how one variable affects the time that it takes the robocopter to fall. Materials • sheets of cardboard • ruler • pencil • scissors • stopwatch • paper clip Procedure 1 A template for a robocopter is shown in Figure 7.3.11. The completed model is shown in Figure 7.3.12. To build your robocopter, cut a copy of the template onto a piece of cardboard. 2 Cut along solid lines and fold along dotted lines as shown by the arrows. 3 Place a$:$8S3wvm6tpKTCTltOxY7H4aYgJSdO2hHAdrsntcp39r3xGfo4zXwpaum6IKm1g2Dh6avAtdk5TIVd
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gjAdyobkN1AiCJwpsxmu6g==$:$h and a south pole. The magnetic field is strongest at the poles of a magnet. Forces 305 ]]></TextData></Page><Page><Page_no>322</Page_no><display_no>306</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[A magnetic field is normally invisible to us. Its shape and strength can be determined either by passing a compass around a magnet, or by examining a sprinkling of iron filings around a magnet. Figure 7.4.2 shows that magnetic field lines point from the north to the south pole. This horseshoe magnet is placed near a mixture of steel and copper filings. Only the steel filings are attracted to the magnet; the copper remains in the pile below. Magnets can be used to separate magnetic metals from a mixture of substances. Figure 7.4.1 N S Figure 7.4.2 Magnetic field lines do not cross, and always run from the north to the south pole of a magnet. science fun Seeing magnetic field$:$Zs8pkp3rXFOKYnFNBONaM+Z7g+vGH0Psh9P9AQ++rl9jcKwBFpbUsp3c/B3Yp6iZALPC/9OOkykc
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mbHyah5yexsK$:$What pattern can you see? 5 Gather up all the iron filings and then test a different magnet. Record this… Describe each pattern you saw. Explain why you think these formed. Magnetic field lines: • show the direction that a compass would point • always run from the north pole to the south pole • do not cross • represent a strong magnetic field when they are bunched closely together • represent a weak magnetic field when they are spaced further apart. 306 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>323</Page_no><display_no>307</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Magnetic domains The metals iron, nickel and cobalt are attracted to magnets, while all other substances are not. Scientists believe that inside each of these metals are tiny magnetic particles called domains. Each of these acts like a mini-magnet, and has a north and a south pole. In a piece of magnetised iron, the domains all point in the same direction. This makes the metal act like a magnet. The domains in a piece of unmagnetised iron point in random directions, as shown in Figure 7.4.4. Types of magnets Temporary and permanent magnets If you stroke an iron nail many times in the same direction with a bar magnet, then the nail begins to act like a magnet itself. This happens because you have pulled all of its domains into line. After a while, the effect wears off and the domains point in random directions once again. In this case, the nail is called a temporary magnet because it only acts like a magnet for a short period of time. Permanent magnets can be made by hitting or heating the metal to make the domains stay in this arrangement. Magnets made from soft iron lose their magnetism more easily than magnets made from cast iron. Data$:$a8KcvAYIGtehSKWzW4Nv1npkU0XQDXCjkqjnZpejjqDDqJaEOWp5NfVgrBESU70B5qpJlgnBHUd/
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U+rHnSbqpReTd4Hog8xBZ+3WXQ==$:$ike poles. Like poles will push away, or repel each other. Poles that are different are called unlike poles. Unlike poles pull together, or attract each other. These situations are shown in Figure 7.4.3. N N S N S S North and north poles repel, pushing each other away. South and south poles also repel. North and south poles attract, pulling together. Magnetic poles that are like (NN or SS) will repel, whereas magnetic poles that are unlike (NS) will attract. We can then say that unlike poles attract while like poles repel each other. Figure 7.4.3 Floating on air The repulsion of magnetic poles can make things float. This is called magnetic levitation. Maglev trains float about 10cm above their tracks. They can reach speeds of 500km/h because they operate with very little friction. Prac1 p. 315 7.7 In-built navigation Many animals, such as honeybees, dolphins, tuna, whales and pigeons, contain tiny crystals of a magnetic material in their brains or stomachs. These act as tiny internal compasses, preventing the animal from getting lost and helping them find their homes. Forces 307 ]]></TextData></Page><Page><Page_no>324</Page_no><display_no>308</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[link between magnetism and electricity, he placed a compass near a wire through which an electric current was flowing. To his surprise, he saw the compass needle move. Oersted realised that electricity flowing through a wire creates a magnetic field around it. If the wire is wound into a coil, it produces a much stronger magnetic field. Inserting a piece of iron inside the coil increases its strength even further. Such a device is called an electromagnet and is shown in Figure 7.4.5. It acts like a bar $:$AmIf6e+1xoAHP7g2y+DwAVIv8VWQeYjGxd1B0xeXHbC4stYb7BFQrInzgApEGnPecsExpv5N5e2U
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C6HjwQ4VQ9PBgn1KUy/7ePXhSH/FLytf9Q6C+ayJ9w==$:$in the wire creates a magnetic field. This field can be turned on and off with the current. Coiling the wire and adding an iron core insert increases the strength of the electromagnet. Figure 7.4.5 Credit cards store information on a magnetic strip. Induction cooktops use electricity to focus a magnetic field above the points on the cooktop where the food is heated. Pots and pans used on the cooktop must be made from iron or steel. Only the contents of the pots heat up. This gives an energy saving of around 30%. A drill has an electric motor. All electric motors contain an electromagnet. Hairdryers, food processors and remote controlled toy cars are other examples of devices with motors. All speakers produce sound due to the vibration of a central cone which contains an electromagnet. An MRI (magnetic resonance imaging) machine is used to look inside the human body to check for disease or injury. The patient lies inside a huge donut-shaped electromagnet. Diseased tissue behaves differently from normal tissue in a magnetic field. Figure 7.4.6 Prac2 p. 316 308 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>325</Page_no><display_no>309</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Electric fields Force fields also exist around electric charges. To understand electric fields, you first need an understanding of the atom and its internal structure. What is an atom? Everything around us is made up of tiny particles called atoms. Atoms themselves are made up of even smaller particles called protons, neutrons and electrons. Neutrons are found deep within an atom in a region called the nucleus. They have no charge. Protons are also found in the nucleus and have a positive charge (+). Electrons move in the space around the nucleus as sho$:$J7V3uG5k3mQGTQWeCrbgtDB+PpPBlviliYdEsyOtAnEICJCT5zShHntwZMwF72f6lQGN4eQAOMJi
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BNaf$:$d up charge when rubbed with another substance. Such materials are called electrical insulators. Electrons cannot flow freely through them. The reason electrical wires are covered with plastic is because plastic is an effective electrical insulator. Metallic objects do not build up a static charge, because electrons can flow through them. These materials, such as a copper electrical wire, are called electrical conductors. Figure 7.4.9 on page 310 shows that when a glass rod is rubbed with a silk cloth, electrons move from the glass rod onto the silk cloth. The glass rod has lost electrons and is now positively charged, because it has more protons than electrons. The silk cloth has gained electrons and is negatively charged, having more electrons than protons. When an object becomes charged (has unequal numbers of protons and electrons), we say that it has static electricity. A force field called an electric field exists around any object that is charged. Any charged object positioned within this field will experience a force, called an electrostatic force (or an electric force). ADDITIONAL Earth’s magnetic field Earth itself has a magnetic field. It behaves as though it has a huge bar magnet in its centre like that shown in Figure 7.4.7. Scientists believe Earth’s magnetic field is generated by molten rock moving inside Earth’s core. axis of rotation true north pole magnetic south pole true south pole Earth is surrounded by a magnetic field. The poles of the imaginary bar magnet inside Earth create magnetic north and south poles, which lie about 3000km from the geographical north and south poles. Figure 7.4.7 ADDITIONAL Forces 309 ]]></TextData></Page><Page><Page_no>326</Page_no><display_no>310</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[If you rub a balloon with a silk cloth, electrons rub off the silk and onto the balloon. Both the silk cloth and the balloon are now charged, and are surrounded by an electric field. Figure 7.4.10 shows what happens when these charged objects are placed next to each other. If placed inside an electric fi$:$P1/7kv0l1jRkaOEp/VYHrlCC7R5DwKBf6qSYkUnWoXJ13zfzQr4wdXtwZMwF72f6geCtSUNBriHw
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Iy8dIou7Gos+kowyBJi0StVE/AidCPET3iHLyuMXcg07hXenhz+sDTCrZpVjVwhY3z8Cpw==$:$al door handle, you could get a shock. Friction between your feet and the carpet rub electrons from the carpet onto you, making you and the carpet both charged. Normally, this charge gradually leaks back out of your shoes to the ground, or into the air, and you become neutral once more. If there is a big build-up of charge, or if you wear rubber-soled shoes that stop the charge from escaping, extra electrons can jump from you to the metal door handle as a spark. You feel this as a small electric shock. If you were to touch another person while charged, electrons would jump onto this person and you would both feel a static shock. Pearson science NSW 8 Unit 5.4 Figure 7.4.9 Electrons are rubbed from the glass rod and jump onto the silk cloth. As a result, the glass rod becomes positively charged and the silk cloth is negatively charged. Glass rod becomes positively charged Silk cloth becomes negatively charged A silk cloth is rubbed against a glass rod. Originally: the number of positive and negative charges on the glass rod and the silk cloth were equal. Negative charges (electrons) jump from the glass rod to the silk cloth Each strand of this girl’s hair is positively charged and is repelling all of the hair around it. Figure 7.4.11 Before rubbing: • objects not charged • no attraction or repulsion • objects have the same charge • they repel After rubbing: • objects have opposite charges • they attract Figure 7.4.10 Objects with like charge are repelled, and objects with unlike charge are attracted. 7.8 Dazzling fashion The Sp4rkl3 skirt is a piece of clothing with a difference: it really shines! This skirt contains circuitry and layers of Teflon and nylon. As the wearer moves around, these layers generate static electricity which can be discharged to power rows of LEDs that are studded into the fabric. Prac3 p. 317 Prac4 p. 317 310 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>327</Page_no><display_no>311</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Lightning A flash of lightning can travel at 140000 km/s! There is enough energy in a single lightning strike to keep a light bulb glowing for a year, which is equivalent to the chemical energy stored in 200 kilograms of explosives! the CurriCulum learning aCross Not many things in nature are as exciting and spectacular as lightning (Figure 7.4.12). Lightning is fascinating but can be frightening! There are about one hundred lightning strikes every second throughout the world. Each year about fifty Australians ar$:$2Uy8ARjbEie5AauuX039eyubjzKHX1EO8vzhQkPbLs1MjxVj/4zb4DYe/k0aWEI2hiLgD/U2I0s4
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uuC00iROd2O0$:$ve the same number of negative and positive charges. That is, the clouds are electrically neutral. During a thunderstorm, the charges separate and drift apart. The bottom of the cloud becomes strongly negative due to a build-up of electrons. The top becomes strongly positive as it loses electrons. When enough static electricity builds up, electrons jump to another region of the cloud, to another cloud or to the ground. This process is shown in Figure 7.4.13. 542C Lightning is a giant spark or flow of charge that can occur between clouds, within the same cloud or from a cloud to the ground. Figure 7.4.13 Personal and social caPability A lightning strike Figure 7.4.12 Forces 311 ]]></TextData></Page><Page><Page_no>328</Page_no><display_no>312</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review The heat from the lightning flash causes the surrounding air to heat rapidly, and it expands explosively, causing the sound of thunder. Other atmospheric events, such as a volcanic eruption, a bushfire or a dust storm, can also produce the build-up of static charge needed to create a lightning strike. Figure 7.4.14 shows lightning produced during a volcanic eruption. Lightning tends to strike the tallest object in a particular area. If you are caught in a thunderstorm, don’t shelter under a tree. If the tree is hit by lightning, electrical charge can jump from the tree to the body of anyone standing nearby in what is called a ‘side- flash’. The best ways to avoid being struck by lightning are to stay indoors or shelter inside a car while not touching any metal. If outdoors, keep away from $:$YR5vLUpb86FOWkH8TxAMNDs0wat63OegIw922ozWT7vJWiuXJcMnxBsEEbMaWkkLU1WvObech4jz
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ZW+ro1tK$:$how you would expect the domains of nails A and B to look tomorrow. Inquiring 1 The spectacle of lightning strikes around a volcanic eruption or through a dust storm is very dramatic. Search for photos of such an event. Present your photos as an electronic album. ICT 2 Static electricity can lead to very dangerous situations. Research and: • describe two situations in which a stray spark could be very dangerous • describe some of the precautions that are taken to prevent a spark being produced in these situations. Present your research as a written or Word document. ADDITIONAL 3 The Earth’s magnetic field has long been used as a navigation guide by people and various species of wildlife. Research and find: • an image showing the structure of Earth’s magnetic field • what scientists believe causes Earth’s magnetic field • what protection is provided by Earth’s magnetic field • the meaning of the term geomagnetic reversal • evidence of past geomagnetic reversal • predictions about how Earth’s magnetic field may change in the future. Present your findings in digital form. ICT ADDITIONAL ICT 314 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>331</Page_no><display_no>315</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations Magnetic shielding Purpose To test which materials a magnetic field can pass through and which materials block a magnetic field. Materials • 50 g mass • paper clips • cotton thread • Blu Tack, Plasticine or sticky-tape • bar magnet • retort stand, bosshead and clamp • sheets of different materials such as cardboard, plastic, aluminium foil, iron, steel, tin, wood, glass, copper Procedure 1 Set up the equipment as shown in Figure 7.4.19. 1 retort stand bar magnet bosshead and clamp paper clip cotton thread sticky-tape, Plasticine or Blu Tack 50 g mass N S Figure 7.4.19 2 Find the maximum distance that can be left between the paper clip and the magnet before the paper clip falls. 3 Insert each different sheet between the paper clip and the magnet and record what happens in your results table. Results In your workbook, construct a table like that shown below to record your observations. Mat$:$VvDL6O5qe/IPdpXYLL3x9bHv49NxksVBvQCnHuj2WEyc3CIsb41HMFalzlIIlKGYHot+3vu/MdLl
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Ow63f5RRsA==$:$TH WALES ]]></TextData></Page><Page><Page_no>335</Page_no><display_no>319</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Analysing 11 Analyse the force diagram in Figure 7.5.3. a State in which direction the boat is moving. b Predict what will happen to the speed of the boat when many fish have been caught in the net. c If the boat is travelling at a constant speed, compare the size of the thrust and drag forces acting on the boat. Evaluating CCT 12 Mariah flicks a coin across the stone benchtop in her kitchen. Later that day, she tries to flick the same coin across sand at the beach. a Predict which coin would travel the greater distance. b Justify your prediction. 13 Figure 7.5.4 shows three blocks of wood resting on different surfaces. If you were to pull each by its hook, propose which block would move with the least friction and which block would move with the most friction. drag from net thrust from propeller fishing net Figure 7.5.3 A B C long round dowels oil Figure 7.5.4 14 A length of wire is used to make coils A, B$:$1L/dWYGuUpRiBqtjB6G4Re9gQbcohI0OS/2seOfqjuHDvbmrNyQ/1nMoo0xcNu/HlcOFauXYl0Tt
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IDwT859MJxiCdASuaoXet1NyIq4LNLQUhg==$:$oratory that do not have their poles marked correctly. One has poles labelled A and B, while the other has poles labelled X and Y. She tests each using a third horseshoe magnet and finds the following combinations attract. (a) 10 N 10 N 15 N 15 N 25 N 20 N 10 N 10 N 30 N 30 N 30 N (b) (c) (d) CCT X S NY CCT Knowing that opposite poles attract, select which of the following pairs of poles will attract. A X and B; Y and A B X and A; X and B C Y and A; Y and B D X and A; Y and B Q4 Active safety features placed in a vehicle are designed to reduce the chance of an accident occurring. Passive safety features lessen the impact of a force if a collision does occur. Select which of the following alternatives lists only active safety features: A seatbelts, ABS (anti-lock brakes), night vision, headrests B ESC (electronic stability control), reversing cameras, good headlights C airbags, ESC (electronic stability control), reversing cameras D seatbelts, ABS (anti-lock brakes), reversing cameras CCT 320 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>337</Page_no><display_no>321</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[GlossaryGlossary Unit 7.1 L Acceleration: increase in speed (verb: accelerate) Active safety features: features in a car that are designed to reduce the chances of an accident occurring Deceleration: decrease in speed (verb: decelerate) Force: a push, pull or a twist that can change an object’s motion Inertia: the tendency of an object to resist change in its motion Newton (N): unit used to measure force Passive safety features: features in a car that are designed to lessen the impact of a force in an accident Unit 7.2 L Air resistance: or drag: friction that acts on an object moving through the air Contact force: force that acts between two objects that touch, or are in contact; for example, friction Friction: force that acts against an object’s motion Lubricants: fluid, such as oil, used to reduce friction between moving parts Unit 7.3 L Force field: region of space in which an object will experience a non-contact force Gravitational field: region of space in which an object will experience a force due to gravity Gravity: force of attraction between any two objects, for example the Earth and a person Mass: the amount of matter in a substance (measured in kilograms) Non-contact force: force that acts on an object from a distance Force Friction Terminal velocity: the point at which a falling body ceases to accelerate, but falls at constant speed, because its weight is balanced by air resistance Weight: the force of gravity pulling on an object, measured in newtons Unit 7.4 L Atoms: tiny particles that make up all matter Con$:$81TRqQ08YSc+L3eVTkKJhUNJBYBZa+FEGVJBaH95daLMgjEMr5NY6kPmpNmvZXHqagtVzNtAQheP
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L0PACGpYle62YwnU8CjCJwNkyIZRcckV5Slxmkpl0tUSinNd$:$r students should be able to: Have you ever wondered... • how we know that the Sun is the centre of the solar system? • how the gravitational pull of the Sun affects the planets? • why we have seasons? • what causes day and night? 322 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>339</Page_no><display_no>323</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[8.1 Look into a clear night sky and you will see stars, cloudy blurs of light made up of even more stars, and most probably part of the Moon. A few of those starry points of light aren’t stars at all but are planets. A couple of ‘stars’ might even shoot across the sky. They aren’t stars either, but meteors. The night sky is Earth’s view of the rest of the universe, its stars, constellations, planets, dwarf planets, moons, meteoroids, asteroids and comets. The night sky Liquid craters Meteorite strikes have marked the Moon with many craters (Figure 8.1.1). Many have peaks in their centre. What forms them? Collect this… • water$:$JwaAJHNaIjCchLaOTSYCDbEo8T9D1hKrFYrnsduIyCVoyEk4EJOp/wAKKnCkWxPhg1cWhFn7Cake
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QOcBCT41N+MXsnX0rU5z449/chD8reY3CgI=$:$s. 5 Carefully observe what happens to the surface of the water as the drop falls in, particularly at its centre. science fun Record this… Describe what happened. Explain why you think this happened. Some meteorites have so much energy that they melt the Moon’s rock, causing it to slosh around and to form a small peak in the centre of the crater. Droplets form a similar peak when they hit liquid water. Figure 8.1.1 Earth in space 323 ]]></TextData></Page><Page><Page_no>340</Page_no><display_no>324</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Observing the night sky Although most people can see about 2000 stars in the night sky with the naked eye, the exact number depends on the weather, how close you are to the bright lights of a city, and whether or not the Moon is in the sky. Not all those bright points of light are the same: some have different colours, some are much brighter or much dimmer than others and some move at different speeds. If you use a telescope, then some of these differences become even more apparent. These visible differences arise because not every point of light in the night sky is a real star. While most points of light are stars, a handful are planet$:$xKL6C177cvEW5KtHSwgT8nifrKRHhMxEkSF1wpilZJTZCnu0reYEjlPfgpgYv/Aw3yQNoaLA3w9T
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cZqCZ5+pTKE0iljQWNNz31F46IPMQWft1l0=$:$cle repeats itself every 30 days (roughly one month). Figure 8.1.2 New moon Dark moon Waxing crescent moon Waning crescent moon First quarter moon Last quarter moon Waxing gibbous moon Waning gibbous moon Full moon Stars Stars are massive burning balls of hydrogen gas. Hydrogen is explosive but the light and heat that comes from stars is not from ‘normal’ hydrogen explosions. It comes from nuclear explosions instead! A nuclear reaction (called a fusion reaction) converts hydrogen into helium, releasing enormous amounts of energy as heat, light and radioactivity as it does so. The nearest star to Earth is the Sun, being ‘only’ 150 million kilometres from us. At this distance, the light and heat from those nuclear explosions takes just over 8 minutes to reach us. The other stars you see in the night sky are much, much, much further away. After the Sun, the next closest star is Proxima Centauri. It is approximately 40 million million kilometres away and it takes 4.2 years for its light to reach us on Earth. The other stars you see are even further away—the light from some of them takes millions of years to reach us! Close but you can’t see it! Proxima Centauri is not far from Alpha Centauri, a double star system that forms one of the pointers leading to the Southern Cross. Proxima Centauri is so close to Alpha Centauri that it is sometimes considered to be part of the same star system. You can see Alpha Centauri in Figure 8.1.3. However, Proxima Centauri itself is so faint that it cannot be seen with the naked eye. After the Sun, Proxima Centauri is the closest star to Earth. Proxima Centauri is near Alpha Centauri but it is too faint to see in this image. Figure 8.1.3 Alpha Centauri Beta Centauri Southern Cross 324 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>341</Page_no><display_no>325</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The Milky Way A band of light runs across the night sky from one horizon to the other. In ancient times, people though$:$VGB0qN6nZn97Fc1JIY0LLppzmGklePRj01R8GkljyloDpOrw/9Rw5VUGzXb7VMRQEhdTY8J2hvP2
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OZR8UcWCdVvX5icYXC7Rh3tvN302LjFpZM8fGvngepQaZdLprQqL2Q/4OFrl9T4=$:$ars are always there in the sky whether it’s night or day. However, you can’t see them in daylight because they can’t compete with the intense brightness of the Sun. Planets Planets are very different from stars. There are no nuclear explosions on the planets and so planets do not make their own light. Instead, they reflect light falling on them from the Sun. This allows us to see them in the night sky. They’re seen as points of light that look very much like real stars. Figure 8.1.5 shows the planets that travel around the Sun. Together, they form the solar system. Although the planets of the solar system are far from Earth, they are much closer to us than the stars. Mercury, Venus, Earth and Mars are the closest planets to the Sun. These are known as the terrestrial (meaning Earth-like) planets. All these planets are rocky with a hard surface. Mercury, Venus and Mars are relatively close to Earth and are often seen in the night sky as a bright or coloured point of light. Mercury and Venus are usually visible before dawn as morning ‘stars’ or just after sunset as evening ‘stars’. At these times, Venus is the brightest ‘star’ in the sky. Mars appears as a red- coloured ‘star’. The eight planets of the solar system can be classified as either terrestrial or gas giants. Pluto is not a planet but is considered to be a dwarf planet. (The distances in this image are not drawn to scale.) Figure 8.1.5 Sun Mercury Earth Jupiter Venus Mars Saturn Uranus Neptune Pluto (dwarf) terrestrial planets gas giants Earth in space 325 ]]></TextData></Page><Page><Page_no>342</Page_no><display_no>326</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[The outer planets of Jupiter, Saturn, Uranus and Neptune are huge balls of gas with a small and rocky core. For this reason, they are commonly known as the gas giants. While Jupiter and Saturn can be seen as ‘stars’ with the naked eye, Neptune and Uranus can only be seen from Earth using a telescope. Other things you might see The Moon, stars and planets are not the only things you might see in the night sky. Other things are up there that look like stars too. Artificial satellites Artificial satellites orbit (travel around) Earth, looking like ‘stars’ travelling slowly across the night sky. They have been placed in orbit as space stations and for purposes such as communication and for observing the weather on Earth’s surface. The International Space Station (ISS) makes its own light, but this is too dull to be seen from Earth. You see satellites because they reflect sunlight back to you. You can see the ISS and another satellite in Figure 8.1.6. Prac2 p. 331 A time-exposure image of the International Space Station (ISS) and another satellite moving across the sky. The solar panels of the ISS reflect sunlight making it $:$acg2zrbFaRiViBYPnF96u/B9s1uGZVBhJADkVI6waZ2sLN9TP+4PXkaw2FYZrh0pIxJ/hFzAl4rw
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1l0=$:$heats up the rock, much like when your bicycle pump gets hot when you quickly pump up a tyre. The enormous heat generated turns the meteoroid into a blazing fireball known as a meteor or ‘shooting star’ (Figure 8.1.7). Most meteors are so small that they burn up completely in the atmosphere. This is why most shooting stars fizzle out before they reach the ground. However, if a meteor is large then part of it might reach the ground before it has completely burnt up. The part that reaches the ground is called a meteorite. Most meteorites are small, but on very rare occasions Earth is struck by a large meteorite. Occasionally, these large meteorites are asteroids that have strayed from the asteroid belt. This belt is a band of rocky objects that orbit the Sun between Mars and Jupiter. The destruction the meteorite causes depends on its size. Smaller meteorites form craters while larger ones can have devastating effects. For example, there is strong evidence that a major meteorite impact caused the extinction of the dinosaurs 65 million years ago. A meteor burning up as it travels through the atmosphere. Figure 8.1.7 path of an artificial satellite path of the ISS 326 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>343</Page_no><display_no>327</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Comets Comets are part of the solar system because they also travel around the Sun. Comets don’t appear often but when they do they are among the most spectacular sights in the sky (Figure 8.1.9). Comets are ‘dirty snowballs’ made of ice mixed with carbon dioxide and other substances. They have a head (known as a coma) and a long shining tail. One of the most famous comets is Halley’s Comet. It reappears in the night sky approximately every 76 years. Its most recent appearance was in 1986. Meteors from comets Astronomers usually don’t know when a small meteoroid might hit Earth’s atmosphere. This makes the appearance of most ‘shooting stars’ very unpredictable. However, some meteors are caused by Earth passing through debris left behind by comets. These are much more predictable events. Sometimes they form meteor ‘showers’ like the one in Figure 8.1.8. A time-exposure image of a meteor shower. Meteor showers happen when$:$jDDKAupI92F51RDRYhtTWyyttCi82DaAmJHkACy81Ag1fueIvM+WpxdpKV65ND0+vUspg5OGp9Sp
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dgK07rNkdTAqyI9CemQEMIvv8GSykAN9kUQBvc6Fs/pD$:$ at least 1200 people. Astronomers estimate that the meteor had a mass of around 10 tonnes, was about 3 metres in diameter and travelling at a speed of 50 000 km/h! In 1908, an even bigger meteor exploded above the largely uninhabited region of Tunguska, Russia, devastating more than 2070 square kilometres of forest. Earth in space 327 ]]></TextData></Page><Page><Page_no>344</Page_no><display_no>328</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review Remembering 1 Name the type of nuclear reaction that powers stars. 2 a Name the nearest star to Earth. b State how long it takes its light to reach Earth. 3 Name the bright band of light that can be seen in the night sky. 4 a State how many stars are visible to the naked eye. b List factors that affect the number of stars able to be seen. 5 List: a the terrestrial planets b the gas giants. Understanding 6 Explain why moonlight can be considered to be sunlight. 7 Explain why planets are sometimes mistaken for stars. 8 Calculate the year in which Halley’s Comet is likely to be next seen from Earth. N 9 Explain why comets and meteor showers are often observed together. Applying 10 One set of planets is also known as the rocky planets. Identify the planets that are most likely to belong to this set. 11 A drop of water is dripped into a glass of water. a Predict the pattern that would result. b Use your prediction to explain why craters formed when meteors struck the Moon. 12 The table below shows the average distances of the planets of the solar system from the Sun. Assume that all the planets are lined up in order from Mercury to Neptune. Use this information and: a name the closest planet to Earth b list the planets from closest to Earth to most distant from Earth. Planet Earth Jupiter Mars Mercury Neptune Saturn Uranus Venus Distance from Sun (millions of km) 150 778 228 58 4498 1427 2870 108 Analysing 13 Contrast: a a planet with a star b a star with the Milky Way c a meteor with a meteorite d a meteoroid with a comet. Evaluating CCT 14 You see many bright points of light in the night$:$HL2fEyN//JBHdt6f1D/NJYFApiR9I4zH2kcy+LcL1kfvEdqVq1/ZuqTFLxTj/vQ/yOuUBwRg/cCt
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8omVuVEktr+7q3S6tugV$:$tachments that can be sent to your teacher. ICT In 1999, NASA’s spacecraft Galileo successfully flew past Io, one of Jupiter’s moons. Figure 8.1.11 Earth in space 329 ]]></TextData></Page><Page><Page_no>346</Page_no><display_no>330</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations Simulating impact craters Purpose To model the surface of the Moon by forming impact craters and simulating erosion. Materials • 4 cups of damp sand or flour • small plastic box or tray (such as a lunch box or take-away food container) • several marbles or ball bearings (of various sizes if possible) • tweezers • piece of tissue paper or cloth • large sheet of plastic (to clean up mess) • digital camera or mobile phone with camera function Procedure 1 Lay out the tray on the large sheet of plastic or set up outside. 2 Fill the tray with flour or sand to a depth of 2–3cm. Keep at least one cup aside for later. 3 Drop a marble or ball bearing into the flour or sand to make an impact crater. 4 Using tweezers, carefully remove the marble or ball bearing. Avoid changing the shape of the crater. 5 Repeat steps 3 and 4 with marbles of different sizes from different heights until a pattern of overl$:$OnP02/Zl57ZzCrgmQqJoe7KwqmUc0DKSCEBxdLkjTDoG6+VmTRin46JgtCIQC+2OPwC7fwITV2vW
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sdXZoBnW9IJ4OpJX9sALnRq3G5CiUPDDR+P7Vqp45kA3mad5wyjG$:$and label important features that you see in them. Practical review 1 Can you tell from the crater patterns you made which craters were formed earlier and which were formed later? If so, explain how. 2 Propose what effect each of the following would have on the pattern of impact craters: a volcanic activity b erosion c earthquakes. 3 It is possible to identify which impact craters were formed after volcanic activity, erosion and earthquakes. Propose what the landscape would look like if a crater was formed after each type of activity. 4 Use information gained from this activity to predict what astronomers could learn from the pattern of impact craters on a moon or a planet. 8.1 330 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>347</Page_no><display_no>331</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Toilet paper solar system Purpose To construct a scale model of t$:$rt++l2dehtEs81fQt33CPFwgnKEUyYeARxipFyaa/PLEgd7IWDx689Z6qH5wx5tYahh7JdTmOJ/w
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WmJvMGcKb5Y69UPxXQoW0HFaLRvLn5iVsEmBsBHPKtDNanWWXiAZG84=$:$ons Throughout history, different groups of people in different parts of the world have looked at the same stars and grouped them together in different ways. The pictures and patterns they have recognised have varied from one culture to another. These patterns are known as constellations. The Southern Cross is a constellation that can only be seen all year round in the southern hemisphere. For this reason, its five stars appear in the flags of a number of countries located south of the equator (Figure 8.2.1). The flags of Australia, Papua New Guinea and Samoa Figure 8.2.1 332 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>349</Page_no><display_no>333</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Finding the South Pole In ancient times, navigators used the Southern Cross to locate the South Pole. You can do this too. First you need to locate the South Celestial Pole. This is the point in the southern night sky around which all the stars seem to rotate. You can find it using two different methods: Method 1: Extend the main axis of the Southern Cross four times. Method 2: Extend the main axis. Construct another line out from the middle of the pointers as shown in Figure 8.2.2. The South Celestial Pole is where the two lines meet. Once the South Celestial Pole is located, drop a line to the horizon; where it hits is the South Pole. Pointers Alpha Centauri Southern Cross 4x South Celestial Pole True South x How to use the Southern Cross to find the South Pole Figure 8.2.2 8.2 Structure of the solar system Explaining the motion of the Earth, Moon, planets and stars has been a puzzle that has taken many centuries to solve. Every day, the Sun, Moon and stars rise in the east and set in the west. By itself, this evide$:$h/J5kCUDKgYHhPz/uN00xl46TY+t5Y5jLXkYAHRA42/nt+lhnmAmVAV0C98yilqVdqaA5tOg7IN1
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EXtEEHOYKwQ=$:$1642–1727) developed laws that explained forces, gravity and the motion of the planets. He is considered to be one of the greatest scientists of all time. Figure 8.2.8 Although Galileo did not invent the telescope, he was the first person to use it for astronomy. These are some of his drawings of the Moon in different phases and its craters that were visible. Figure 8.2.7 Galileo’s observations led him to challenge the geocentric model and instead support the heliocentric model of Copernicus. Galileo lived in Italy at a time when religious authorities were very powerful. His outspoken manner brought him into conflict with the authorities and he was imprisoned and banned from publishing his ideas and from writing to other scientists. Galileo relied on his scientific technique and observations and not on the accepted way of thinking of his time. For this he is recognised as the ‘father of modern science’. In 1596, the German mathematician Johannes Kepler (1571–1630) produced a heliocentric model that closely matched existing astronomical data. His model assumed that planetary orbits were elliptical rather than circular. This was a revolutionary idea—at that time, circles were believed to have special, almost mystical, properties. 8.3Prac1 p. 342 Earth in space 335 ]]></TextData></Page><Page><Page_no>352</Page_no><display_no>336</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Discovering the outer planets The planets Uranus and Neptune cannot be seen with the naked eye and so a telescope was required to discover them. The German-born British astronomer William Hershel (1738–1822) used a telescope in 1781 to discover the planet Uranus, and German astronomer Johann Galle (1812–1910) used one to observe Neptune in 1846. Discovering the dwarf planets Pluto was discovered in 1930 by American astronomer Clyde Tombaugh (1906–1997). It was quickly classified as the ninth planet of the solar system. In 1992, it was then found that Pluto was part of the Kuiper Belt, a band of relatively small objects orbiting in the Sun at the outer edge of the solar system. Over the next 10 years, other Pluto-sized objects were discovered. Some of these are shown in Figure 8.2.9. For astronomers, this raised a difficult question—if Pluto is a plan$:$VLnJef2v/MRvD8VwiA6iqub3qOD6CduWw2o5NF2LBApl0o5+C55x1NC6tcN5lLqOSTziRXMuJ6wy
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CVMJ$:$fining a planet as a celestial body that: • is in orbit around the Sun • has sufficient mass and gravity (is big enough) to be nearly spherical (round) • has enough gravity to clear the neighbourhood around its orbit of dust, rock and other objects. Pluto orbits the Sun and is roughly spherical but it is part of the Kuiper Belt. This means that it has failed to clear its orbit. For this reason, Pluto is no longer considered to be a planet but is now classified as a dwarf planet. Haumea, Eris and Makemake are also classified as dwarf planets, as is the asteroid Ceres located in the asteroid belt between Mars and Jupiter. Exploring the solar system The development of rockets in the mid-twentieth century allowed us to leave Earth and explore the solar system directly. The Apollo missions that landed on the Moon between 1969 and 1972 had human crews. Apollo XI was the first to land. You can see one of its astronauts (Buzz Aldrin) on the Moon’s surface in Figure 8.2.10. Prac2 p. 343 Prac3 p. 343 Still a planet to some In 2009, the government of Clyde Tombaugh’s home state of Illinois, USA, ‘overruled’ the International Astronomical Union. Within the state of Illinois at least, Pluto is still considered a planet and March 13 (the anniversary of its discovery) is celebrated as Pluto Day. 336 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>353</Page_no><display_no>337</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Since these missions, humans themselves have not ventured outside Earth’s immediate orbit. All other space probes to the Moon and beyond have been without human crew, although many have carried robots. Some space probes have landed or crashed onto the planets or their moons. Others have flown by, taking photos and measurements as they did so. These missions continue to this day—one of the most recent being the Curiosity probe. It landed its rover on Mars in 2012. Most of the missions of the twentieth century were sent by USA or USSR (now Russia). However, twenty- first century space exploration has become tr$:$N3UpttWmsyenlv5m/drFzbWTjZZYnl/5SRnVrfehc5+2NdIa9Mt1OdWG4rmpZW8wpbiMB8HazOxt
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L6Rec2Cf/hp2sNk8kCTKEQHog8xBZ+3WXQ==$:$ saucepan or a canoe, while other celestial objects might be seen as an emu in the sky. 20 January–18 February 19 February–20 March 21 March–19 April 20 April–20 May 21 May–20 June 21 June–22 July 23 July–22 August 23 August–22 September 23 September–22 October 23 October–21 November 22 November–21 December 22 December–19 January Aquarius Pisces Aries Taurus Gemini Cancer Leo Virgo Libra Scorpio Sagittarius Capricorn aboriginal consTellaTions When looking for patterns in the stars, people are naturally reminded of objects they are familiar with from everyday life. It is not surprising that people from different cultures with different lifestyles would identify different constellations. The Aboriginal Emu-in-the-sky constellation is seen by looking at the dark clouds of dust between the stars rather than the stars themselves. Figure 8.2.11 8.4 The zodiac is made up of 12 constellations.Figure 8.2.12 338 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>355</Page_no><display_no>339</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[For example, consider the group of stars in Figure 8.2.13. The ancient Greeks called this group of stars Orion after a famous hunter from mythology. He is shown in Figure 8.2.14. The bright stars at the corners represent the hunter’s hands and feet, the group of stars across the middle is his belt with a scabbard (a sheath or cover for the sword) sticking out of it. However, from the southern hemisphere this image appears upside down! For this reason, many Australians don’t see a hunter but instead see a saucepan. As Figure 8.2.15 shows, Orion’s sword is the handle of the Saucepan. The Yolngu people of the Northern Territory know this group of stars as Djulpan or the canoe, shown in Figure 8.2.16. Here, the sword/ saucepan handle represents a fishing lining trailing behind the canoe in the water. review 1 List four constellations of the zodiac. 2 Explain why the ancient Greeks and the Yolngu people saw different shapes in the same set of stars. IU 3 The Yolngu people identified the three bright$:$Fc3AVTmnQbV0Py07zwm4xiVtHfKsRkMhJVAkB+t8XhfTWfXGRtpszKWfbnAOwid6dtWQnpsVmJHh
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oC6161596d7SFM7NY4E=$:$h of these pictures portrays the geocentric model and which shows the heliocentric model. b Justify your answer by referring to specific features of each illustration. Evaluating CCT 16 The term Copernican revolution is sometimes used to describe any big shift in understanding. Propose a reason why. 17 Newton claimed that his achievements in explaining the solar system were due to the fact that he ‘stood on the shoulders of giants’. a Name some of these giants. b Propose reasons why he made this claim. 8.2 340 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>357</Page_no><display_no>341</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Creating CCT 18 a Construct a diagram for a new constellation that would fit the star pattern shown in Figure 8.2.18. (You don’t need to use every star.) b Name your new constellation after what you think it looks like. 19 Construct a poster or presentation to explain to a group of younger students why Pluto is $:$C7jykpwwoAmTW/s3ReuBKuXOqhUxQufxRLAF1mU6wWUmoYKXnoRFJXk3p5mCqEw9cngvu6Z3Ako5
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VnufxWxh/NMt$:$as thought to be located • what scientific discovery proved that Planet X does not exist. Present your research as a poster or a digital presentation such as a PowerPoint. ICT 3 Research the following astronomers, classifying them as supporters of the geocentric model or the heliocentric model of the solar system: • Heraclides Ponticus • Pythagoras • Khayyan • Aristotle • Tycho Brahe Present the results of your research as a table. 4 Research a constellation recognised by a cultural group living in your local area. IU DD • Find a diagram of the constellation. • Retell any stories or legends associated with the constellation • Identify the scientific names of the stars in the constellation. • Identify any Western constellations that are associated with the same group of stars Present your research as a poster or as a digital presentation such as a PowerPoint. ICT ICT Earth in space 341 ]]></TextData></Page><Page><Page_no>358</Page_no><display_no>342</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations Constructing a telescope continued on next page Constructing a telescope Purpose To construct a simple telescope. Materials • 2 biconvex$:$LmMblc0CAvsN3ZYGwpJsZtAgiULu7Zj/fbb6M9/RBgTHpEAJMNLpNUqjQ3LVT5c8IMGwwpjixg4Q
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T0GB3Grk+KvK2YEPEwkTRKK3Q64DfQ==$:$ns into the ends of the cardboard tubes as shown in Figure 8.2.19. 1 SAfeTy Do not point your telescope at the Sun. Determining focal length To determine the focal length of a biconcave lens, follow these steps: • Hold your lens so that lots of light can enter it (perhaps stand in sunlight). • Hold a blank sheet of paper behind your lens. • Move your lens slowly back and forth (alternatively, move the sheet of paper back and forth) until the light passing through the lens has focused to a single bright point. Figure 8.1.20 shows what is happening. • Measure the distance between the lens and the sheet of paper. This is the focal length of your lens. weak attened lens long focal length short focal length strong curved lens F F Parallel rays of light are brought together at a point called the focus (F) on the other side of a convex lens. The greater the curve of the lens, the stronger the lens is and the shorter its focal length, or distance between the lens and the focus. Figure 8.2.20 4 Add the two focal lengths. Adjust the cardboard tubes so that the distance between each lens corresponds to this distance. 5 Label the end of the telescope which has the lens with the shorter focal length, eyepiece. Label the other end of the telescope, objective. 6 Point the objective lens of the telescope at a distant object and look through the eyepiece lens. Sketch the image you observe. 7 Reverse the telescope (i.e. look through the objective lens). Sketch the image you observe. Figure 8.2.19 tape tape convex lens convex lens cardboard tubes 8.2 342 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>359</Page_no><display_no>343</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Constructing a telescope continued STUDeNT DeSIGN Visiting dwarf planets Purpose To use simulation software to observe a number of dwarf planets. Materials • computer or tablet computer • a planetarium program or app such as GoSkyWatch Planetarium, SkyGlobe, Celestia or WorldWide Telescope Procedure 1 Set the program to show the sky as it will app$:$0MiSnykmlJkkgd+AXjGA3KQ4qF8MJgAXUt3LzvmldYvk98mCO0neiGgJN8hREg5LI8tXS/JViJoR
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hZpbKS+MrlwheithClRbHmdwK6e6mSXdfKfLGDUzHL77TKwpwKRpNIpvAt7b7uiDzEFn7dZd$:$n and your assessment of its risks. If they approve, collect all the required materials and start work. 3 SAfeTy A Risk Assessment is required for this investigation. 2 Search for Ceres. 3 Zoom in until the image of the dwarf planet fills the screen. Sketch it. 4 Zoom out to identify and sketch any moons orbiting the dwarf planet. 5 Repeat steps 2–4 for other dwarf planets, such as Pluto, Eris, Makemake and Haumea. Practical review 1 List the three characteristics of a planet. 2 Dwarf planets are not classified as planets because they do not have one of the characteristics of a planet. Describe the feature that most dwarf planets lack. Hints In your design: • consider using curved mirrors instead of lenses for the objective • try changing the focal lengths of the objective and eyepiece to alter the magnification of the telescope • design apparatus that will allow the telescope to be kept still and focused on an object in the sky. Practical review 1 Compare the image observed using your telescope with the ones observed using the simple telescope constructed in prac 1. 2 Estimate the magnification of your telescope. 3 Evaluate the success of this investigation. Was your telescope an improvement? Practical review 1 Describe the image sketched in step 6. The magnification of the telescope is how much it has increased the size of the image (such as doubled, tripled). Estimate the magnification of your telescope. 2 Contrast the images sketched in steps 6 and 7. Earth in space 343 ]]></TextData></Page><Page><Page_no>360</Page_no><display_no>344</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Gravity is the pulling force that makes you fall off your skateboard or your chair. It causes rain to fall and rivers to flow to the sea, and it is the force that causes our tides. Gravity, tides and orbits8.3 Drawing ellipses Can you draw an accurate ellipse? Collec$:$F8TdLzHmcdw6WzbaACROWuws7C5Yn1KfwjlUu1SusM6wmdMPhtzbBZcMX2EUYO/dS5CTKBrOB0Io
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QWft1l0=$:$pulled towards the person sitting next to you or to a large skyscraper that you are walking past. Gravity is only noticeable when one of the objects is really massive, such as a planet, moon or star. These objects have strong gravitational fields around them that attract anything else that is nearby, including you. Earth has a gravitational field like that shown in Figure 8.3.2. The effect of distance The gravitational fields around planets, moons and stars weakens rapidly as you move away from them. For example, Earth’s gravitational field is a little weaker on the top of its highest mountain (Mt Everest), than at sea level. However, the difference is too small for you to notice and can only be detected by extremely sensitive instruments. By the time you get to the Moon, Earth’s pull is weak, much weaker than at Earth’s surface. The gravitational field of Earth pulls masses towards its centre. Figure 8.3.2 Prac1 p. 351 Earth in space 345 ]]></TextData></Page><Page><Page_no>362</Page_no><display_no>346</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Orbits The gravitational fields around planets, moons and stars are often strong enough to ‘trap’ other masses so that they travel continuously around them in a path known as an orbit. For example, Earth and the other planets of the solar system are ‘trapped’ by the gravitational field of$:$Kf7xLfA6BAs0ARAC/9Xhcxl9bUCxW13z1+N+dXB4rHyyPdGB8WyOphI1gHmkD2a94S7HddjHi30C
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03TervR0iVsXyJmNGB8vBz6Ja+PpzQ==$:$ orbit Saturn, forming a spectacular series of rings around the planet. Figure 8.3.4 have been placed in orbit by us humans. Some are used to transmit information such as internet and telephone conversations, while others scan the Earth for everything from erosion and bushfires to espionage (spying). The largest artificial satellite in orbit around Earth is the International Space Station (ISS), shown in Figure 8.3.5. Explaining orbits Imagine you are on the top of a tall mountain with a handful of tennis balls. Drop one and it will fall to your feet because gravity pulls it downwards. If you throw the ball horizontally, it still falls but it takes a curved path to the ground, landing at a distance away from you. Now imagine that you could throw the ball so fast that it kept on falling, never hitting the Earth. If you could do this then the ball would be in orbit. The ball will then keep ‘falling’ around Earth forever, needing no extra push or power to keep it orbiting. Unstable orbits If a satellite is travelling too slowly then it will slowly spiral in. This is what most artificial satellites eventually do. Likewise, if a satellite is travelling too fast then it will slowly spiral outwards. The Moon is doing this: it strays a tiny 3.8cm away from Earth each year! Prac2 p. 352 The International Space Station (ISS) is an artificial satellite orbiting Earth. It has a crew of six on board at most times. Figure 8.3.5 346 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>363</Page_no><display_no>347</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Figure 8.3.6 shows how. An orbit like this can only happen outside Earth’s atmosphere because there is no air resistance and therefore nothing to slow the satellite down. Orbits in the solar system Orbits are elliptical in shape. Ellipses are oval-shaped closed loops. Some are long, thin ovals while others are almost perfect circles. For example, the orbits of Venus, Earth and Neptune around the Sun are nearly circular. Mars, Jupiter, Saturn and Uranus have more elliptical (stretched) orbits. Mercury and the dwarf planet Pluto have quite elliptical orbits. Comets from deep space are sometimes trapped by the gravitational field of the Sun and sweep around it in long thin orbits. Comets often orbit in a plane very different from that of the planets. A typical orbit of a comet is shown in Figure 8.3.7. A ball will fall to Earth when thrown. A ball will still fall to Earth even if you throw it faster. It will just land further away from you. A ball will go into orbit if it is thrown really fast. It will fall continually and never hit Earth. Throw an object slowly and it will land back on Earth. However, if$:$YK3IyUfD4+pK70tUIHPsTk1Uwf9uasrn5rzAmSXLexh9i6vWAtLgUcq/mO9zKBiVPyY0TvmH9/hI
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XVQiw8ifvHoErCuB44Dg$:$of its phases. One is shown in Figure 8.3.8. The dwarf planet Pluto orbits in a different plane from the rest of the solar system. Its long, thin elliptical orbit sometimes places Pluto closer to the Sun than Neptune. Comets usually orbit the Sun in a different plane too. Figure 8.3.7 comet Pluto How much of the Moon we see depends on the angle of the sunlight falling on it. This phase is called a gibbous Moon. Figure 8.3.8 Earth in space 347 ]]></TextData></Page><Page><Page_no>364</Page_no><display_no>348</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Sometimes the orbits of the Moon around Earth and Earth around the Sun cause all three bodies to align so that the Moon blocks sunlight from reaching Earth, or Earth blocks sunlight from reaching the Moon. When this happens, as eclipse occurs. Solar eclipses A solar eclipse occurs whenever light from the Sun is blocked by the Moon, casting a shadow onto Earth like that shown in Figure 8.3.9. Whatever part of Earth’s surface is in shadow is plunged into darkness until the Moon moves out of the way again. Figure 8.3.10 shows the view from Earth when it happens. Solar eclipses can be complete (in the umbra, where the shadow is full and dark) or partial (in the penumbra, where the shadow is less dense). umbra Moon penumbra The Moon is too small to block light from the Sun over the entire Earth, and so its shadow falls on only part of Earth’s surface. Only these parts experience a solar eclipse. Figure 8.3.9 Astronomers use solar eclipses to view the corona or very outer layer of the Sun, and the solar flares that burst from it. Figure 8.3.10 Lunar eclipses During a lunar eclipse, the Earth blocks light from reaching the Moon. As the Moon passes along its orbit, it first passes through the penumbra, causing a partial lunar eclipse. It then moves through the umbra, forming a total lunar eclipse, before moving back into the penumbra and then back into the sunlight. Figure 8.3.11 shows how this happens. In Figure 8.3.12 you can see what the Moon looks like during a lunar eclipse. A dragon ate the Moon! The ancient Chinese and Vikings both thought that a lunar eclips$:$oqRFjXal7niB+xmzxREuPBsjJ8lJsTJQ320NIXVps9CHw5UIfhbjwqI/te/ZcduwfRbUx1DjdCYv
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iS/MJ1/SgOI=$:$k like the tide has just gone out. However, tsunamis have nothing to do with tides since they are not caused by the gravitational pulls of the Moon and Sun. Earth in space 349 ]]></TextData></Page><Page><Page_no>366</Page_no><display_no>350</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review Remembering 1 List two examples of forces that act through a field. 2 List five things around you that are pulling you with a weak gravitational force. 3 Name one thing that is currently pulling you with a strong gravitational force. 4 Name one: a natural satellite of the Sun b natural satellite of Earth c artificial satellite of Earth. Understanding 5 Explain w$:$rN9CqMuGQRt4gqpd0F4C6TuXReO7A1XG5SHKHNRywWA3ObppR1u0Yt/s6DRRwCL7wUHVqQRkHoCx
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6TiPpWn8HHBrRYrEsiXYlBekLbP1CeGShFY9$:$Use this definition to explain how lunar eclipses are related to the Moon. Analysing 10 Contrast a natural satellite with an artificial satellite. 11 Contrast the orbits of Pluto and comets around the Sun with the orbits of the planets of the solar system. Evaluating CCT 12 One way of constructing an ellipse is shown in science4fun on page 344. Propose what would happen to the shape of the ellipse if the drawing pins were placed closer together. 13 Imagine that you shoot a gun horizontally off a tall mountain, the bullet going so fast that it goes into orbit around Earth. It could be extremely dangerous if you stay on top of the mountain. Propose why. Creating CCT 14 The Moon orbits the Earth in approximately 30 days but solar and lunar eclipses don’t occur every 30 days. Instead, we usually see the Moon in one of its phases. a A full Moon occurs whenever we see all of its face lit by the Sun. Construct a diagram showing how the Sun, Moon and Earth might be arranged so that a full Moon occurs without causing a lunar eclipse. b A new Moon happens when the far-side of the Moon is lit and we on Earth look at its unlit side. Construct another diagram that shows how this might happen without causing a solar eclipse. Inquiring 1 Search the internet to find and view: ICT • simulations showing the orbits of the planets of the solar system • simulations showing the orbits of the Moon around Earth and Earth around the Sun • live vision on NASA TV from the International Space Station in orbit around Earth. 2 Find the tide information for next seven days for NSW. Find the times and heights of the predicted high and low tides for: • Sydney (Fort Denison) • a beach, town or port on the north coast of NSW • beach, town or port on the south coast of NSW. Present the information you find as a table that can be used to compare the tides at each place. 8.3 350 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>367</Page_no><display_no>351</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations8.3 Go jump! Each planet in the solar system has a different mass and so gravity depends on which planet you are on. This means that you can jump different heights on different planets. This assumes that the surface is solid! Purpose To calculate how high you could j$:$1CxQabRy6YUfOwcd3gTrjZgh79mggj79Q8V0fzFs9bOKxDarzMhpLWtrp4doD/8noPTfpDXxW4/l
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pMLASDklXeI=$:$ump. 6 Repeat two more times and record your jump heights. 7 Swap roles so that everyone in your group has a jump. Results 1 Record all your jump heights in a table like the one shown below. Name of jumper Jump 1 (cm) Jump 2 (cm) Jump 3 (cm) Average jump (cm) 1 2 Calculate your average jump height by: N • adding: Jump 1 + Jump 2 + Jump 3 • dividing: by 3. 3 Calculate the height you could jump on the Moon and other planets by: • dividing: your average jump ÷ gravity. N Planet or moon Gravity compared to Earth’s (Earth = 1) Predicted jump height (cm) Earth 1 Moon 0.16 Mercury 0.38 Venus 0.91 Mars 0.38 Jupiter 2.36 Saturn 0.92 Uranus 0.89 Neptune 1.1 Practical review 1 Identify the celestial body/bodies on which you could jump: a the highest b the lowest c about the same as on Earth. 2 Find the world records for various athletics, such as high jump and pole vault, then calculate what they would be on the other planets. 3 Astronauts on the Moon were able to jump higher than on Earth but not as high as you calculated above. Propose reasons why. N Earth in space 351 ]]></TextData></Page><Page><Page_no>368</Page_no><display_no>352</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations8.3 Orbits Purpose To use a model of an orbit and to determine the effect of changing gravity. Hypothesis Which satellite do you think will orbit faster—a satellite around a planet with high gravity or a satellite around a planet with low gravity? Before you go any further with this investigation, write a hypothesis in your workbook. Materials • plastic casing of ballpoint pen or short length of plastic or metal tubing • string or strong cotton thread • rubber bung with hole • washers • large open area Procedure 1 Tie the string or cotton thread securely to the rubber bung by passing it through the hole a number of times and then knotting it tightly. 2 Pass the string or thread through the tubing and tie a couple of washers on the other end, as shown in Figure 8.3.14. SAfeTy The rubber bung will be travelling fast in wide circles so make sure you wear$:$Le7oxrzJWtAev7Ulh0p5KhCKBosEC4eMf5T6zlgFk1As48m4n0pKlbmMH3pDwLDW55P9qPIWW5Dl
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ELAoc/dtzsvTmpfH2mYxr98V7QCE5tIYwKotGdvXAQdOAR6KT49n$:$and others move out of it. Every five minutes another photograph was taken to produce this image of the Sun setting in the west. Figure 8.4.1 8.6Prac1 p. 359 The year Like all the other planets in the solar system, Earth orbits the Sun. It travels at an average speed of 108000km/h and takes 365 1 4 days to complete one revolution (one complete orbit). A complete orbit is shown in Figure 8.4.3. The time taken by a planet to revolve around the Sun is known as its year. For Earth, a year is 3651 4 days. The quarter day makes setting up a calendar very difficult and so a calendar year is normally taken as 365 days. However, every four years the calendar needs to ‘catch up’, so an extra day is added to make a leap year of 366 days. This extra day is 29 February. A day is the time it takes for Earth to spin around on its axis once completely. As Earth spins, only half is bathed in sunlight at any one time. This half experiences daylight. The dark half experiences night. Figure 8.4.2 N nightday 23.5º S 8.7 1 day 1 year S Sun Earth A year is the time it takes for Earth to completely revolve or orbit around the Sun. A day is the time it takes to rotate completely on its own axis. Figure 8.4.3 354 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>371</Page_no><display_no>355</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Leap years Every fourth year is not always a leap year. Use the following key to predict whether a year is a leap year or not. Can the year be divided by 400 exactly? If yes, then go to 2. If not, can the year be divided by 100 exactly? If yes, then go to 1. If not, can the year be divided by 4 exactly? If yes, then go to 2. 1 It’s a normal year. 2 It’s a leap year. N Leap years Problem Is 2016 a leap year? Solution 2016 ÷ 400 = 5.04 (cannot be divided by 400 exactly) 2016 ÷ 100 = 20.16 (cannot be divided by 100 exactly) 2016 ÷ 4 = 504 This is a whole number and so 2016 is a leap year. Practice N Calculate whether the following years will be leap years. a 2015 b 2020 c 2100 WORKED EXAMPLE Climate The regions around the equator always point towards the Sun, and the sunlight that falls on them is bright and its heat is concentrated. This makes it hot all the time with very little variation between the seasons. The North and South poles are always the coldest $:$Xoo+FmlELKRqGHsl1OY4n6+Xty6QaW9qXIWjdRZhkQbJf1acmuOFx5XvYcFcKjwp2NGmH0ggFm8P
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JRKxjINzKsKQQQRZBXO8crSt/gtvw7HmG+9Dm3lcIMu/DzYRBEk1Q+iDzEFn7dZd$:$he Northern Territory and the Kimberley region of Western Australia are always hot, while Tasmania and southern Victoria are usually much cooler. Prac2 p. 360 The Earth is spherical so sunlight hits its different regions at different angles. This results in different climates. Figure 8.4.4 N S Sunlight at the poles covers a wider surface area so temperatures are far colder. Sunlight is concentrated on a smaller area at the equator so the tropics are warm all year round. equator line Earth in space 355 ]]></TextData></Page><Page><Page_no>372</Page_no><display_no>356</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Seasons Earth’s axis is not ‘vertical’ but is tilted at an angle of 23.5°. This tilt gives us our seasons. As Figure 8.4.5 shows, some parts of Earth point towards the Sun. This exposes them more, so that the sunlight falling on them is more concentrated. These parts experience summer. Other parts of Earth are pointed away from the Sun. In these regions the sunlight is spread over a larger area. This results in lower temperatures and winter. Earth exposes different parts of its surface to the Sun as it moves along its orbit. Australia experiences summer from December through to March because this is when the southern hemisphere is pointed towards the Sun. Meanwhile, the nor$:$O/HZCFB8d3PpZ5lkNz4c2u3t5mxm5nKyOhdzcLzmVCPuSKUlAaR4GXoWtgtsDRfxVr0O/gQyrsBl
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aeAglBa0/DJ86XLtyD8Ot5cZ9ggkhWJ+a2PHs5Pog8xBZ+3WXQ==$:$ght. The summer solstice marks the day on which there is the longest time in daylight. southern summer solstice 21 December Spring and autumn equinox marks the days on which an equal amount of time is spent in daylight and in the dark. southern winter solstice 21 June southern autumn equinox 21 March southern spring equinox 21 September Earth’s tilted axis causes sunlight to be more concentrated on some parts of Earth than others at different times of the year. This causes the seasons. Figure 8.4.5 Simulating seasons What happens when sunlight falls on Earth at an angle? Collect this… • torch • sheet of paper (preferably graph paper or with a grid) • 30cm ruler Do this… 1 Place the sheet of paper on the floor or on a desk or table. 2 Hold the torch 30cm from the paper and shine its light directly onto the paper. science fun 3 Trace around the ‘pool’ of light. 4 Repeat, but this time direct the torch so that its light falls on the paper at an angle. 5 Once again, trace around the ‘pool’ of light. Record this… Describe what happened. Explain why you think this happened. vertical summer sun, keeping the house cool. However, the more angled winter sun can get underneath them and enter the house to keep it warm. 356 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>373</Page_no><display_no>357</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Unit review Remembering 1 State which of the following is correct. Earth spins from: A north to south B east to west C south to north D west to east 2 Recall the following terms by matching each with the correct number of days: A year 365 A ‘normal’ calendar year 366 A leap year 365.25 or 3651 4 Understanding 3 Define the following terms: L a 1 day b 1 year c 1 revolution. 4 Describe the problems that would be caused if our calendar year was taken as 3651 4 and not 365 and 366 days. 5 Explain why countries near the equator are usually much hotter than countries on other parts of Earth. 6 The equinox marks the time in the year that the length of day and night are exactly the same. Predict: a how many equinoxes occur each year b the seasons in which they occur. 7 Explain how a sundial works. Applying 8 Use a sketch to help define the following terms: a Earth’s axis b the equator c the poles. 9 Some people only have a birthday every four years. Identify the date on which they were born. 10 The surface of Earth is moving at incredible speeds due to its spin. Identify the part(s) on Earth’s surface that are: a moving the fastest b just turning on the spot. 11 Calculate whether the following years were/will be leap years or not. N a 1896 b 1900 c 2225 d 2400 12 Usethe labels on the diagram shown in Figure 8.4.6 to identify the part(s) of Earth (A, $:$BSFhXSt7EzIl/DC9K7tE4U88kAPRQxgdcsG2zCucYj+z/jQj18a4XDeMsEely8c9drOMprgrHWtk
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QPg=$:$les. ICT 3 Research the times for the rotation and orbits of the Earth, Sun and Moon. Present your findings on a diagram. 4 Al Battani was a tenth century astronomer who accurately measured the length of the year. Research Al Battani and find: • his full name, years and place of birth and death • where he lived and worked • the length of the year as determined by him • his other scientific and mathematical achievements • the name of the Moon crater named after him • how he has been honoured in science fiction. Present the information you find as a series of dot points. IU 358 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>375</Page_no><display_no>359</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations Day and night Purpose To model day and night on Earth. Materials • balloon • string or cotton • felt-tip pen • access to a globe • access to a bright light (such as a projector, spotlight, data projector or similar) Procedure 1 Blow up your balloon and tie it off so that no gas can escape. This is your Earth, and its tied-off end represents the North Pole. 2 Tie a length of string or cotton to the North Pole. 3 Use the felt-tip pen to draw on the balloon the position of the equator, South Pole and International Date L$:$1HXhgNRvUhnYA4skqEcAT1djIuoiFjAHCeesTNaPoYekTJ7pHt0fNSnZ4DgxVbxjc6xcJfVSXbiP
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Uw==$:$ce string or cotton International Date Line equator W E spin balloon Figure 8.4.7 Practical review 1 The Sun rises in the east and sets in the west, but you rotated your ‘Earth’ in the opposite direction. Explain why there is a difference. 2 Identify which coast of Australia: a first came into ‘daylight’ b was the last to move into ‘night’. 3 Perth is on a different time zone from Melbourne, Sydney and Brisbane, being two hours ‘behind’ them. Use your model to explain why different time zones are needed in Australia. 4 Assess how accurate this model is in showing Earth, its spin, and its day. 8.4 Earth in space 359 ]]></TextData></Page><Page><Page_no>376</Page_no><display_no>360</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Practical investigations8.4 Angles and temperature Purpose To test whether the angle of sunlight affects the surface temperature on Earth. Hypothesis Which do you think will heat up a thermometer faster—a lamp shining directly over it or a $:$5XHuvWOnQr5PDgnMFUcpeRvv39HblnKeV8jX7elgVlavrh8cHDNk76Li6kXQYElwDa5U/8S9nRRw
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HnvqBpdqu7lw0oIeCvmlFD7Kd3/Rkyx9$:$o the board to secure it. 3 Place the two blocks the same distance from the lamp. Figure 8.4.8 shows the set-up. • Block A: Lay one block flat on the desk so that the light from the lamp falls on it at an angle. • Block B: Use some books to chock up the other block so that it is at an angle to the desk and the light falls directly on it. 4 Turn on the lamp. 2 SAfeTy The lamp will get very hot so avoid touching it. lamp wood blocks black plastic (taped) thermometers books Block A Block B Figure 8.4.8 Results 1 Record the temperature of each thermometer every minute for at least five minutes. 2 Place your results in a table like the one shown below. Time (min) Block A Block B 1 2 3 4 5 Practical review 1 Identify which block (A or B) showed the greatest increase in temperature. 2 Identify which block (A or B) modelled the surface of the Earth in: a far north Queensland b southern Tasmania. 3 Use your results to explain why: a the tropics are found near the equator b icebergs are only found near the poles. 4 a Construct a conclusion for your investigation. b Assess whether your hypothesis was supported or not. 360 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>377</Page_no><display_no>361</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Chapter review Remembering 1 State whether the following statements are true or false. a Only large masses like planets, stars and moons have a gravitational field. b The further you go out from a planet, the weaker its gravity becomes. c A day on Earth is the time it takes for Earth to revolve once around the Sun. d Earth has four seasons because of its tilted axis. e Pluto is a planet. 2 List the four planets that are known as: a terrestrial planets b gas giants. 3 Name two important scientists or philosophers who supported: a the geocentric model b the heliocentric model. 4 List evidence that caused the geocentric model to be dropped in favour of the heliocentric model. Understanding 5 Describe what a ‘shooting star’ really is. 6 Encke’s Comet was seen in April 2007 and again in August 2010. Calculate how long it takes for Encke’s Comet to complete one orbit around the Sun. 7 Draw a diagram that shows what retrograde motion is. 8 Neptune and Uranus were the last planets to be discovered. Propose a reason why. 9 Outline four important observations that space missions to the planets have brought. 10 Explain why constellations vary from one culture to another. 11 Describe the shape of an ellipse. 12 The Moon can still be seen during a lunar eclipse. Explain why. 13 Explain why Earth experiences four seasons each year. 14 Describe how the day and year are related to Earth’s movement. N 15 Predict what the world would be like if there were $:$VEgHpZU8T/dpHq0ptOkv2oJNsqrRMfuh5fCD/BVyJ1l3/lwwQfROzm2JqZZ1EPLRfF4oFAqKdTQx
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260v6UDH/cJmhnoruSNUcfepYGKknAuoYryTZG106IPMQWft1l0=$:$. Construct your own mnemonic to help you remember the order of the planets of the solar system. 28 People in prehistoric times reacted to solar and lunar eclipses with amazement and fear because they did not know why they happened. Imagine you are one of these people seeing a solar eclipse for the first time. Construct a short news item for your local newspaper Neanderthal News or the current affairs show Neolithic Nightly. Your item must describe what you saw and how people around you reacted. 29 Use the following ten key words to construct a visual summary of the information presented in this chapter: stars constellation gravity orbit ellipse Sun Earth Moon tides comet 8.8 362 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>379</Page_no><display_no>363</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[Thinking scientifically The Bayer system is used to name stars within a constellation. It uses the Greek alphabet to name them, with alpha (α) being the brightest star. Beta (β) is used for the next brightest, gamma (γ) for the next and so on. The two pointers of the Southern Cross are α-Centauri$:$1AJWMiAbrZuIo+qlWvzb087cI0k8MlXUOhMaoFzRFq35mgqs1fCYPRGAFuUqQrXp/0Qlygt3/CyO
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Ti/fVsRYrPy0xaO3beLdqmLHFmNIyex8JczXEvyNSm8MfCtkTmffCUDFftFf6IPMQWft1l0=$:$in which the solar system is located Phases: different shapes of the Moon as seen from Earth Solar system: the Sun and all the planets, satellites, asteroids, comets and other bodies revolving around it Terrestrial: Earth-like, rocky. The terrestrial planets are Mercury, Venus, Earth and Mars Unit 8.2 L Astronomer: a scientist who studies the stars, planets and other celestial objects Constellation: a group of stars which form a recognisable pattern in the night sky Dwarf planet: a small celestial body that is in orbit around the Sun and is nearly round in shape but with insufficient gravity to sweep its orbit Geocentric model: model of the universe with Earth at its centre Comet Retrograde motion Heliocentric model: model of the universe with the Sun at its centre Retrograde motion: apparent loop-like motion of the planets as seen from Earth Unit 8.3 L Eclipse: the total or partial obscuring of one celestial body by another Ellipse: oval shape Gravitational force field: invisible field that causes masses to be attracted to each other Lunar eclipse: when the Earth blocks sunlight from reaching the Moon Orbit: path a planet takes around a star, or a moon or artificial satellite takes around a planet Penumbra: less dense shadow of an eclipse Satellite: object in orbit around another larger object Solar eclipse: when the Moon blocks sunlight from reaching Earth Tides: bulges in the ocean caused by the combined gravitational pull of the Moon and Sun Umbra: full, dark shadow of an eclipse Unit 8.4 L Axis: the line connecting the North Pole with the South Pole. The Earth rotates around this axis Day: the time a planet takes to rotate once completely on its own axis Revolution: one complete orbit around the Sun Seasons: on Earth, summer, autumn, winter, spring; caused by the tilt of a planet’s axis Year: the time a planet takes to revolve once around the Sun Day 364 PEARSON science NEW SOUTH WALES ]]></TextData></Page><Page><Page_no>381</Page_no><display_no>365</display_no><Title><TextData><![CDATA[]]></TextData></Title><TextData><![CDATA[A abiotic factors 182, 187, 188, 222, 224, 225 Aboriginal and Torres Strait Islander people classification scheme 264–5, 267, 268–9 constellations of 338–9 fire and 199 seasons 358 water usage and 127–8 resources and 49, 94, 95 see also Indigenous Australians absolute zero 53, 59 acceleration 278, 279, 280, 321 acids 14, 45, 169, 231 active safety features 282, 320, 321 adaptations 182, 183, 187, 188, 190, 225 address (organisms) 222 agnatha 241, 247, 273 agriculture 213–15 aim 29, 41 air 61, 73, 88–9, 96, 116, 135, 144, 177 airbags 282, 283 air resistance 290, 300, 321 air temperature 72, 116, 135 Al Battani 358 alcohol 67–8, 160, 161 Aldrin, Buzz 336–7 algae 134, 167, 194, 195, 196 Alpha Centauri 324, 363 amphibians 241, 242, 273 animal kingdom 237–48, 255 animals 193, 196, 203–4, 237, 259, 262, 263, 265, 270, 271, 272, 273, 293, 307 annelids 238, 239, 240, 246, 273 Antarctica 122, 254 anti-lock brakes (ABS) 282, 283 Apollo missions 336–7 aqueous solution 140, 143, 159, 166, 178 aquifer 115, 128, 137, 168, 169 Archimedes 74 Aristarchus 334, 340 Aristotle 302, 333, 340 arthropods 238, 240–1, 247, 263, 273 artificia$:$w9rQbSVpli6BaqF/o5hlMwGyJTc4b0K3Liti0CNZ139UYr9DxOtUoFud8u+/+z2HBnjew63SDLMc
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wbADc28YSTpIGsKn+zs7fWubv2dueA==$:$eetle 195, 196 water cycle 112–21, 129, 131, 133, 135, 137 water management 106, 122–32, 161, 165, 166, 168, 174 water states 115–16 water temperature 68–9, 70 water trap (‘S’ bend) 173, 174 water treatment 169, 173 water vapour 88, 116, 177 wave energy 104, 134, 135 weather, classification of 268–9 weathering 91, 136 weeds 229–30, 273, 234 weight 73, 289, 292, 299–300, 301, 318, 321, 362 wet season 223, 358 wetland ecosystem 125, 130, 181, 222 wheat 207, 213 wildlife corridor 217–18 wind energy 52, 101, 102, 104, 108, 109, 111, 134, 135, 137, 168 winter solstice 356, 357 Wollemi pine (Wollemi nobilis) 252, 256, 263 wombat 192, 243 wood 73, 134 wooden block, friction and 294, 295 Y year 354–5, 357, 358, 364 Yolngu people 264–5, 339 Z zodiac 338–9 zoology 4, 5, 11 PEARSON science NEW SOUTH WALES370 ]]></TextData></Page> </AssetRef>
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