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 NEW 14 Cambridge R 20 IGCSE FO ® Biology Third Edition D G Mackean Dave Hayward 9781444176469_IGCSE_Biology_FM.indd 1 8/18/14 9:38 PM  Unless otherwise acknowledged, the questions and answers that appear in this book and CD were written by the author. Although every effort has been made to ensure that website addresses are correct at time of going to press, Hodder Education cannot be held responsible for the content of any website mentioned in this book. It is sometimes possible to find a relocated web page by typing in the address of the home page for a website in the URL window of your browser. Hachette UK’s policy is to use papers that are natural, renewable and recyclable products and made from wood grown in sustainable forests. The logging and manufacturing processes are expected to conform to the environmental regulations of the country of origin. Orders: please contact Bookpoint Ltd, 130 Milton Park, Abingdon, Oxon OX14 4SB. Telephone: (44) 01235 827720. Fax: (44) 01235 400454. Lines are open 9.00–5.00, Monday to Saturday, with a 24-hour message answering service. Visit our website at www.hoddereducation.com ® IGCSE is the registered trademark of Cambridge International Examinations © DG Mackean 2002 and Dave Hayward 2014 First published in 2002 by Hodder Education An Hachette UK Company London NW1 3BH Second edition published 2009 This third edition published 2014 Impression number 5 4 3 2 1 Year 2018 2017 2016 2015 All rights reserved. Apart from any use permitted under UK copyright law, no part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying and recording, or held within any information storage and retrieval system, without permission in writing from the publisher or under licence from the Copyright Licensing Agency Limited. Further details of such licences (for reprographic reproduction) may be obtained from the Copyright Licensing Agency Limited, Saffron House, 6–10 Kirby Street, London EC1N 8TS. The drawings are by DG Mackean, whose copyright they are unless otherwise stated, and whose permission should be sought before they are reproduced or adapted in other publications. Cover photo © mathisa – Fotolia Proudly sourced and uploaded by [StormRG] First edition layouts by Jenny Fleet Kickass Torrents | TPB | ET | h33t Original illustrations by DG Mackean, prepared and adapted by Wearset Ltd Additional illustrations by Ethan Danielson, Richard Draper and Mike Humphries Natural history artwork by Chris Etheridge Full colour illustrations on pages 7–10 by Pamela Haddon Third edition typeset in 11/13pt ITC Galliard Std by Integra Software Services Pvt. Ltd., Pondicherry, India Printed and bound in Italy A catalogue record for this title is available from the British Library ISBN 978 1444 176 469 9781444176469_IGCSE_Biology_FM.indd 2 8/18/14 9:38 PM Contents Acknowledgements vi To the student viii 1 Characteristics and classification of living organisms 1 Characteristics of living organisms 1 Concept and use of a classification system 2 Features of organisms 6 Dichotomous keys 21 2 Organisation and maintenance of the organism 24 Cell structure and organisation 24 Levels of organisation 29 Size of specimens 33 3 Movement in and out of cells 36 Diffusion 36 Osmosis 40 Active transport 48 4 Biological molecules 51 Biological molecules 51 Proteins 53 Structure of DNA 54 Water 55 5 Enzymes 59 Enzyme action 59 6 Plant nutrition 66 Photosynthesis 66 Leaf structure 77 Mineral requirements 81 7 Human nutrition 86 Diet 86 Alimentary canal 95 Mechanical digestion 98 Chemical digestion 100 Absorption 103 8 Transport in plants 110 Transport in plants 110 Water uptake 114 Transpiration 116 Translocation 121 iii  9 Transport in animals 124 Transport in animals 124 Heart 125 Blood and lymphatic vessels 132 Blood 136 10 Diseases and immunity 142 Pathogens and transmission 142 Defences against diseases 148 11 Gas exchange in humans 156 Gas exchange in humans 156 12 Respiration 165 Respiration 165 Aerobic respiration 165 Anaerobic respiration 169 13 Excretion in humans 174 Excretion 174 14 Co-ordination and response 180 Nervous control in humans 181 Sense organs 186 Hormones in humans 190 Homeostasis 192 Tropic responses 197 15 Drugs 205 Drugs 205 Medicinal drugs 205 Misused drugs 207 16 Reproduction 213 Asexual reproduction 213 Sexual reproduction 219 Sexual reproduction in plants 221 Sexual reproduction in humans 232 Sex hormones in humans 241 Methods of birth control in humans 243 Sexually transmitted infections (STIs) 245 17 Inheritance 250 Inheritance 250 Chromosomes, genes and proteins 250 Mitosis 254 Meiosis 255 Monohybrid inheritance 259 iv 18 Variation and selection 270 Variation 270 Adaptive features 274 Selection 279 19 Organisms and their environment 284 Energy flow 284 Food chains and food webs 285 Nutrient cycles 292 Population size 296 20 Biotechnology and genetic engineering 305 Biotechnology and genetic engineering 305 Biotechnology 305 Genetic engineering 310 21 Human influences on ecosystems 316 Food supply 316 Habitat destruction 320 Pollution 324 Conservation 334 Examination questions 347 Answers to numerical questions 384 Index 385 v Acknowledgements I am grateful to Eleanor Miles and Nina Konrad at Hodder Education for their guidance and encouragement. I would also like to thank Andreas Schindler for his skill and persistance in tracking down suitable photographs, and Sophie Clark, Charlotte Piccolo and Anne Trevillion were invaluable in editing the text and CD. With special thanks to Margaret Mackean for giving her blessing to the production of this new edition. The publishers would like to thank the following for permission to reproduce copyright material: Examination questions All the examination questions used in this book are reproduced by permission of Cambridge International Examinations. Artwork and text acknowledgements Figure 3.27 from J.K. Brierley,Plant Physiology (The Association for Science Education, 1954); Figure 4.4 from J.Bonner and A.W. Galston, Principles of Plant Physiology (W.H. Freeman and Co., 1952); Figure 6.27 from S.B.Verma and N.J. Rosenberg, Agriculture and the atmospheric carbon dioxide build-up , (Span, 22 February 1979); Figure 7.4 from World Resources Report 1998-9; Table 7.2 from National Nutrient Database, Agricultural Research Service, United States Department of Agriculture; Figure 7.18 from John Besford, Good Mouthkeeping; or how to save your children’s teeth and your own while you’re about it (Oxford University Press, 1984); Figure 9.12 and Figure 15.6 from Royal College of Physicians (1977), Smoking or Health. The third report from the Royal College of Physicians of London (London: Pitman Medical); Figure 10.2 from World Resources Report 1998-9; Figure 10.8 (after) Brian Jones, Introduction to Human and Social Biology, 2/e (John Murray, 1985); Table p.173 from Donald Emslie-Smith et.al., Textbook of Physiology, 11th Revised Edition (Churchill Livingstone, 1988); Figure 16.58 from G.W. Corner, The Hormones in Human Reproduction (Princeton University Press, 1942); Figure 19.12 from Robert H. Whittaker, Communities and Ecosystems, 2nd editon (Macmillan College Textbooks, 1975); Figures 19.27, 19.28 and 19.30 from Trevor Lewis and L.R. Taylor, Introduction to Experimental Ecology (Academic Press, 1967); Figure 19.22 from James Bonner, The World’s People and the World’s Food Supply (Carolina Biology Readers Series, 1980), copyright © Carolina Biological Supply Company, Burlington, North Carolina; Figure 19.24 from F.M. Burnett, Natural History of Infectious Disease, 3rd edition (Cambridge University Press, 1962); Figure 21.15 from W.E. Shewell-Cooper, The ABC of Soils (English Universities Press, 1959); Figure 21.8 from Clive A. Edwards, Soil Pollutants and Soil Animals (Scientific American, 1969), copyright © 1969 by Scientific American Inc.; Figure 21.30 from J.E. Hansen and S. Ledeboff, New Scientist (22 October 1985). Every effort has been made to trace or contact all rights holders. The publishers will be pleased to rectify any omissions or errors brought to their notice at the earliest opportunity. 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We want to This third edition has been completely restructured test your knowledge with interactive multiple choice to align the chapters in the book with the syllabus. questions that cover both the Core and Extended Each chapter starts with the syllabus statements to curriculum. These are organised by chapter. be covered in that chapter, and ends with a checklist, Together, the textbook and CD-ROM will summarising the important points covered. The provide you with the information you need for the questions included at the end of each chapter are Cambridge IGCSE syllabus. I hope you enjoy using intended to test your understanding of the text you them. have just read. If you cannot answer the question I am indebted to Don Mackean for a substantial straightaway, read that section of text again with the amount of the content of this textbook. Since 1962, question in mind. There are past paper examination he has been responsible for writing excellent Biology questions at the end of the book. books to support the education of countless students, To help draw attention to the more important as well as providing an extremely useful source of words, scientific terms are printed in bold the first information and inspiration for your teachers and time they are used. As you read through the book, their teachers. Don’s diagrams, many of which are you will notice three sorts of shaded area in the text. reproduced in this book, are legendary. Material highlighted in green is for the Cambridge Dave Hayward IGCSE Extended curriculum. Areas highlighted in yellow contain material that is not part of the Cambridge IGCSE syllabus. It is extension work and will not be examined. viii  Characteristics and classification of living organisms 1 Characteristics of living organisms The basic features of plants and animals Listing and describing the characteristics of living organisms The main features of groups in the animal kingdom Concept and use of a classification system The main features of groups in the plant kingdom How organisms are classified, using common features The main features of viruses Defining species Using the binomial system of naming species Dichotomous keys Features of organisms Use of keys based on easily identifiable features Identifying the main features of cells Construction of dichotomous keys The five-kingdom classification scheme Characteristics of living Key definitions If you are studying the extended syllabus you need to learn more organisms detailed definitions of some of the characteristics of living things. Movement is an action by an organism or part of an organism causing a change of position or place. Key definitions Most single-celled creatures and animals move about as a Movement is an action by an organism causing a change of whole. Fungi and plants may make movements with parts position or place (see Chapter 14). of their bodies (see Chapter 14). Respiration describes the chemical reactions in cells that Respiration describes the chemical reactions in cells that break break down nutrient molecules and release energy (see down nutrient molecules and release energy for metabolism. Chapter 12). Most organisms need oxygen for this (see Chapter 12). Sensitivity is the ability to detect and respond to changes in Sensitivity is the ability to detect or sense stimuli in the the environment (see Chapter 14). internal or external environment and to make appropriate Growth is a permanent increase in size (see Chapter 16). responses (see Chapter 14). Reproduction is the processes that make more of the same kind Growth is a permanent increase in size and dry mass by an of organism (see Chapter 16). Single-celled organisms and increase in cell number or cell size or both (see Chapter 16). bacteria may simply keep dividing into two. Multicellular Even bacteria and single-celled creatures show an increase plants and animals may reproduce sexually or asexually. in size. Multicellular organisms increase the numbers Excretion is the removal from organisms of toxic materials and of cells in their bodies, become more complicated and substances in excess of requirements (see Chapter 13). change their shape as well as increasing in size (see ‘Sexual Nutrition is the taking in of materials for energy, growth and reproduction in humans’ in Chapter 16). development (see Chapters 6 and 7). Excretion is the removal from organisms of the waste products of metabolism (chemical reactions in cells including All living organisms, whether they are single- respiration), toxic materials and substances in excess of celled or multicellular, plants or animals, show requirements (see Chapter 13). the characteristics included in the definitions Respiration and other chemical changes in the cells above: movement, respiration, sensitivity, growth, produce waste products such as carbon dioxide. Living reproduction, excretion and nutrition. organisms expel these substances from their bodies in various ways (see Chapter 13). One way of remembering this list of the Nutrition is the taking in of materials for energy, growth and characteristics of living things is by using the development. Plants require light, carbon dioxide, water mnemonic MRS GREN. The letters stand for the and ions. Animals need organic compounds and ions and first letters of the characteristics. usually need water (see Chapters 6 and 7). Mnemonics work by helping to make the material Organisms can take in the materials they need as solid food, as animals do, or they can digest them first and you are learning more meaningful. They give a then absorb them, like fungi do, or they can build them structure which is easier to recall later. This structure up for themselves, like plants do. Animals, using ready- may be a word, or a name (such as MRS GREN) or a made organic molecules as their food source, are called phrase. For example, ‘Richard of York gave battle in heterotrophs and form the consumer levels of food chains. vain’ is a popular way of remembering the colours of Photosynthetic plants are called autotrophs and are usually the rainbow in the correct sequence. the first organisms in food chains (see Chapters 6 and 19). 1 9781444176469_IGCSE_Biology_1.indd 1 8/18/14 9:38 PM  1 Characteristics and classification of living organisms Concept and use of a a species are almost identical in their anatomy, physiology and behaviour. classification system Closely related species are grouped into a genus (plural: genera). For example, stoats, weasels and Key definitions polecats are grouped into the genus Mustela. A species is a group of organisms that can reproduce to produce fertile offspring. Binomial nomenclature The binomial system is an internationally agreed system in Species must be named in such a way that the name is which the scientific name of an organism is made up of recognised all over the world. two parts showing the genus and the species. ‘Cuckoo flower’ and ‘Lady’s smock’ are two common names for the same wild plant. If you are You do not need to be a biologist to realise that not aware that these are alternative names this could there are millions of different organisms living on lead to confusion. If the botanical name, Cardamine the Earth, but it takes a biologist to sort them into a pratensis, is used, however, there is no chance of meaningful order, i.e. to classify them. error. The Latin form of the name allows it to be There are many possible ways of classifying used in all the countries of the world irrespective of organisms. You could group all aquatic organisms language barriers. together or put all black and white creatures into People living in Britain are familiar with the the same group. However, these do not make very appearance of a blackbird – a very common garden meaningful groups; a seaweed and a porpoise are visitor. The male has jet black plumage, while the both aquatic organisms, a magpie and a zebra are female is brown. Its scientific name is Turdus merula both black and white; but neither of these pairs has and the adult is about 24 cm long (see Figure 1.1). much in common apart from being living organisms However, someone living in North America would and the latter two being animals. These would be describe a blackbird very differently. For example, artificial systems of classification. the male of one species, Agelaius phoeniceus, has A biologist looks for a natural system of black plumage with red shoulder patches and yellow classification using important features which are flashes, while the female is speckled brown. It is shared by as large a group as possible. In some cases about the size of a sparrow – only about 20 cm long it is easy. Birds all have wings, beaks and feathers; (see Figure 1.2). A British scientist could get very there is rarely any doubt about whether a creature confused talking to an American scientist about a is a bird or not. In other cases it is not so easy. As a blackbird! Again, the use of the scientific name avoids result, biologists change their ideas from time to time any confusion. about how living things should be grouped. New The binomial system of naming species is an groupings are suggested and old ones abandoned. internationally agreed system in which the scientific name of an organism is made up of two parts Species showing the genus and the species. Binomial means The smallest natural group of organisms is the species. ‘two names’; the first name gives the genus and the A species can be defined as a group of organisms that second gives the species. For example, the stoat and can reproduce to produce fertile offspring. weasel are both in the genus Mustela but they are Members of a species also often resemble each different species; the stoat is Mustela erminea and the other very closely in appearance, unless humans weasel is Mustela nivalis. have taken a hand in the breeding programmes. All The name of the genus (the generic name) is cats belong to the same species but there are wide always given a capital letter and the name of the variations in the appearance of different breeds (see species (the specific name) always starts with a small ‘Variation’ in Chapter 18). An American Longhair letter. and a Siamese may look very different but they Frequently, the specific name is descriptive, for have few problems in breeding together. Robins, example ­edulis means ‘edible’, aquatilis means ‘living blackbirds and sparrows are three different species in water’, bulbosus means ‘having a bulb’, serratus of bird. Apart from small variations, members of means ‘having a jagged (serrated) edge’. 2 9781444176469_IGCSE_Biology_1.indd 2 8/18/14 9:38 PM  Concept and use of a classification system      Figure 1.1 Turdus merula ♂   Figure 1.2 Agelaius phoeniceus ♂ If you are studying the extended syllabus you need at the other. It makes a joint with two other bones to be able to explain why it is important to classify (the radius and ulna) which join to a group of small organisms. By classifying organisms it is possible to wrist bones. The limb skeleton ends with five groups identify those most at risk of extinction. Strategies of bones (the hand and fingers), although some of can then be put in place to conserve the threatened these groups are missing in the bird. species. Apart from the fact that we have no right to The argument for evolution says that, if these wipe out species forever, the chances are that we will animals are not related, it seems very odd that such deprive ourselves not only of the beauty and diversity a similar limb skeleton should be used to do such of species, but also of potential sources of valuable different things as flying, running and swimming. products such as drugs. Many of our present-day drugs If, on the other hand, all the animals came from are derived from plants (e.g. quinine and aspirin) and the same ancestor, the ancestral skeleton could have there may be many more sources as yet undiscovered. changed by small stages in different ways in each We are also likely to deprive the world of genetic group. So we would expect to find that the basic resources (see ‘Conservation’ in Chapter 21). pattern of bones was the same in all these animals. By classifying organisms it is also possible to There are many other examples of this kind of understand evolutionary relationships. Vertebrates all evidence among the vertebrate animals. have the presence of a vertebral column, along with Classification is traditionally based on studies of a skull protecting a brain, and a pair of jaws (usually morphology (the study of the form, or outward with teeth). By studying the anatomy of different appearance, of organisms) and anatomy (the study groups of vertebrates it is possible to gain an insight of their internal structure, as revealed by dissection). into their evolution. Aristotle was the first known person to attempt to devise The skeletons of the front limb of five types of a system of classification based on morphology and vertebrate are shown in Figure 1.3. Although the anatomy. He placed organisms in a hierarchy according limbs have different functions, such as grasping, to the complexity of their structure and function. flying, running and swimming, the arrangement Indeed, some of his ideas still existed just 200 years ago. and number of the bones is almost the same in all He separated animals into two groups: those with blood five. There is a single top bone (the humerus), with and those without, placing invertebrates into the second a ball and socket joint at one end and a hinge joint group and vertebrates into the first. However, he was 3 9781444176469_IGCSE_Biology_1.indd 3 8/18/14 9:38 PM  1 CharaCteristiCs and ClassifiCation of living organisms not aware that some invertebrates do have a form Plants have been classified according to their of haemoglobin. Using blood as a common feature morphology, but appearances can be deceptive. would put earthworms and humans in the same group! The London Plane tree and the British Sycamore Earthworm blood is red: it contains haemoglobin, were considered to be closely related because although it is not contained in red blood cells. of the similarity in their leaf shape, as shown in ball and hinge five groups of bones, Figure 1.4. socket joint joint each arranged in a ‘chain’ 1 (shoulder) (elbow) (hand and fingers) 2 3 4 one bone two bones group of 5 (humerus) (radius and ulna) small bones (wrist) (a) pattern of bones in human forelimb 1 2 3 radius 4 5 wrist Figure 1.4 Leaves of the British Sycamore (left) and London Plane (right) humerus ulna (b) lizard However, a closer study of the two species exposes radius ulna wrist major differences: leaf insertion (how they are humerus 1 arranged on a branch) in London Plane is alternate, 2 while it is opposite in the Sycamore. Also, their fruits 3 are very different, as shown in Figure 1.5. (c) bird radius wrist humerus 1 2 3 5 4 ulna (d) whale humerus ulna radius wrist 1 Figure 1.5 Fruits of the British Sycamore (left) and London Plane (right) 2 The scientific name of the London Plane is Platanus acerifolia (meaning ‘leaves like an Acer’); that of the British Sycamore is Acer pseudoplatanus (‘pseudo’ means ‘false’). They do not even belong in the same genus. 3 The use of DNA has revolutionised the process 5 4 of classification. Eukaryotic organisms contain (e) bat chromosomes made up of strings of genes. The Figure 1.3 Skeletons of five vertebrate limbs chemical which forms these genes is called DNA 4 9781444176469_IGCSE_Biology_1.indd 4 8/18/14 9:39 PM  Concept and use of a classification system (which is short for deoxyribonucleic acid). The Human and primate evolution is a good example DNA is made up of a sequence of bases, coding for of how DNA has been used to clarify a process of amino acids and, therefore, proteins (see Chapters 4 evolution. Traditional classification of primates (into and 17). Each species has a distinct number of monkeys, apes and humans) was based on their chromosomes and a unique sequence of bases in anatomy, particularly their bones and teeth. This put its DNA, making it identifiable and distinguishable humans on a separate branch, while grouping the from other species. This helps particularly when other apes together into one family called Pongidae. different species are very similar morphologically (in However, genetic evidence using DNA provides appearance) and anatomically (in internal structure). a different insight – humans are more closely The process of biological classification called related to chimpanzees (1.2% difference in the cladistics involves organisms being grouped together genome – the complete set of genetic material of according to whether or not they have one or more the organism) and gorillas (1.6% different) than to shared unique characteristics derived from the orang-utans (3.1% different). Also, chimpanzees are group’s last common ancestor, which are not present closer to humans than to gorillas (see Figure 1.6). in more distant ancestors. Organisms which share a Bonobos and chimps are found in Zaire and were more recent ancestor (and are, therefore, more closely only identified as different species in 1929. The two related) have DNA base sequences that are more species share the same percentage difference in the similar than those that share only a distant ancestor. genome from humans. Orang-utan Gorilla Chimpanzee Bonobo Human 48 chromosomes 48 chromosomes 48 chromosomes 48 chromosomes 46 chromosomes 0 1 common ancestor, 2 now extinct 3 4 time/millions of years ago 5 6 common ancestor, 7 now extinct 8 common ancestor, 9 now extinct 10 11 12 common ancestor, now extinct 13 14 15 Figure 1.6 Classification of primates, based on DNA evidence 5 9781444176469_IGCSE_Biology_1.indd 5 8/18/14 9:39 PM  1 Characteristics and classification of living organisms Features of organisms Extension work All living organisms have certain features in As scientists learn more about organisms, common, including the presence of cytoplasm and classification schemes change. Genetic sequencing cell membranes, and DNA as genetic material. has provided scientists with a different way of studying relationships between organisms. The All living organisms also contain ribosomes three-domain scheme was introduced by Carl in the cytoplasm, floating freely or attached to Woese in 1978 and involves grouping organisms membranes called rough endoplasmic reticulum using differences in ribosomal RNA structure. (ER). Ribosomes are responsible for protein Under this scheme, organisms are classified into synthesis. three domains and six kingdoms, rather than five. The sixth kingdom is created by splitting the Prokaryote kingdom into two. The domains are: The Whittaker five-kingdom scheme 1 Archaea: containing ancient prokaryotic organisms which do not have a nucleus surrounded The largest group of organisms recognised by by a membrane. They have an independent biologists is the kingdom. But how many kingdoms evolutionary history to other bacteria and their should there be? Most biologists used to favour biochemistry is very different to other forms of life. the adoption of two kingdoms, namely Plants 2 Eubacteria: prokaryotic organisms which do not and Animals. This, however, caused problems have a nucleus surrounded by a membrane. in trying to classify fungi, bacteria and single- 3 Eukarya: organisms that have a membrane-bound celled organisms which do not fit obviously into nucleus. This domain is further subdivided into the either kingdom. A scheme now favoured by many kingdoms Protoctist, Fungus, Plant and Animal. biologists is the Whittaker five-kingdom scheme A summary of the classification schemes proposed consisting of Animal, Plant, Fungus, Prokaryote by scientists is shown in Figure 1.7. and Protoctist. A two-kingdom scheme: Linnaeus It is still not easy to fit all organisms into Animal Plant the five-kingdom scheme. For example, many protoctista with chlorophyll (the protophyta) show A five-kingdom scheme: Whittaker important resemblances to some members of the Animal Plant Fungus Prokaryote Protoctist algae, but the algae are classified into the plant kingdom. A six-kingdom system: Woese Viruses are not included in any kingdom – they Animal Plant Fungus Eubacteria Archaebacteria Protoctist are not considered to be living organisms because they lack cell membranes (made of protein and A three-domain system: Woese lipid), cytoplasm and ribosomes and do not Eubacteria Archaea Eukarya demonstrate the characteristics of living things: they Figure 1.7 A summary of the classification schemes proposed by do not feed, respire, excrete or grow. Although scientists viruses do reproduce, this only happens inside the cells of living organisms, using materials provided by An outline classification of plants and animals follows the host cell. and is illustrated in Figures 1.8–1.11. This kind of problem will always occur when we try to devise rigid classification schemes with The plant kingdom distinct boundaries between groups. The process These are made up of many cells – they are of evolution would hardly be expected to result multicellular. Plant cells have an outside wall made of in a tidy scheme of classification for biologists cellulose. Many of the cells in plant leaves and stems to use. contain chloroplasts with photosynthetic pigments, e.g. chlorophyll. Plants make their food by photosynthesis. 6 9781444176469_IGCSE_Biology_1.indd 6 8/18/14 9:39 PM  features of organisms COELENTERATES FLATWORMS COELENTERATES FLATWORMS COELENTERATES FLATWORMS Planarians ( 2) Hydra ( 5) Planarians ( 2) Jelly-fish ( 0.3) Planarians ( 2) Hydra ( 5) Hydra ( 5) Jelly-fish ( 0.3) Jelly-fish ( 0.3) Liver fluke ( 1.4) Tapeworm ( 0.5) Coral Anemone ( 0.5) ( 0.3) Tapeworm ( 0.5) Coral Liver fluke ( 1.4) Liver fluke ( 1.4) Tapeworm ( 0.5) Anemone ( 0.5) 0.3) (Coral Anemone ( 0.5) ( 0.3) ANNELIDS MOLLUSCS ANNELIDS Mussel MOLLUSCS ( 0.5) ANNELIDS MOLLUSCS Mussel Earthworm (Mussel 0.5) ( 0.5) ( 0.5) Ragworm ( 1) Land snail ( 0.8) Earthworm (Earthworm 0.5) Ragworm ( 1) Land snail ( 0.8) ( 0.5) Ragworm ( 1) Land snail ( 0.8) Slug ( 0.5) Slug ( 0.5) Slug ( 0.5) Water snail ( 1) Leech ( 1) Octopus ( 0.15) Water snail ( 1) Leech ( 1) Water snail ( 1) Octopus ( 0.15) Leech ( 1) Octopus ( 0.15) ARTHROPODS CRUSTACEA ARTHROPODS INSECTS ARACHNIDS MYRIAPODS ARTHROPODS CRUSTACEA INSECTS ARACHNIDS MYRIAPODS Cyclops CRUSTACEA Ladybird INSECTS ARACHNIDS MYRIAPODS ( 14) ( 2) Cyclops Ladybird Millipede ( 0.8) (Cyclops 14) Mite ( 8) Woodlouse ( 1.5) (Ladybird 2) Butterfly ( 0.5) ( 14) ( 2) Millipede ( 0.8) Mite ( 8) Woodlouse ( 1.5) Butterfly ( 0.5) Millipede ( 0.8) Mite ( 8) Woodlouse ( 1.5) Butterfly ( 0.5) Spider ( 1.5) Spider ( 1.5) Wasp ( 1.3) Spider ( 1.5) Wasp ( 1.3) Wasp ( 1.3) Centipede Crab ( 0.4) ( 0.8) Barnacle ( 2) Dragonfly ( 0.3) Centipede Crab ( 0.4) 0.8) (Centipede Barnacle Dragonfly ( 0.3) Figure 1.8Crab The( animal 0.4) kingdom; examples 2) of five( invertebrate groups (phyla) ( 0.8) Barnacle ( 2) Dragonfly ( 0.3) 7 9781444176469_IGCSE_Biology_1.indd 7 8/18/14 9:39 PM  1 CharaCteristiCs and ClassifiCation of living organisms FISH AMPHIBIA FISH AMPHIBIA Frog ( 0.4) Frog ( 0.4) Perch Perch ( 0.2) Trout ( 0.2) ( 0.2) Trout ( 0.2) Toad ( 0.4) Toad ( 0.4) Plaice Tadpoles (× 0.8) Plaice ( 0.14) Tadpoles (× 0.8) ( 0.14) Newt ( 0.6) Dogfish ( 0.13) Newt ( 0.6) Dogfish ( 0.13) REPTILES BIRDS REPTILES BIRDS Kestrel Kestrel ( 0.06) ( 0.06) Robin Robin ( 0.25) Slow-worm ( 0.4) ( 0.25) Slow-worm ( 0.4) Lizard ( 0.5) Lizard ( 0.5) Mallard Kingfisher Snake ( 0.18) Mallard ( 0.1) Kingfisher ( 0.2) Snake ( 0.18) ( 0.1) ( 0.2) MAMMALS MAMMALS Bat ( 0.2) Bat ( 0.2) Seal Seal ( 0.03) ( 0.03) Mouse Mouse ( 0.4) ( 0.4) Deer ( 0.03) Deer ( 0.03) Squirrel Dog Squirrel Dog ( 0.03) ( 0.15) ( 0.03) ( 0.15) Figure 1.9 The animal kingdom; the vertebrate classes 8 9781444176469_IGCSE_Biology_1.indd 8 8/18/14 9:39 PM  features of organisms ALGAE BRYOPHYTES ALGAE BRYOPHYTES ALGAE BRYOPHYTES (a) LIVERWORTS (a) LIVERWORTS Sea lettuce (a) LIVERWORTS Sea lettuce ( 0.1) (Sea0.1) lettuce ( 0.1) Laminaria Laminaria ( 0.1) ( 0.1) Laminaria Pellia ( 2) Pellia ( 2) Lophocolea ( 3) ( 0.1) Pellia ( 2) Lophocolea ( 3) Lophocolea ( 3) Bladder wrack Bladder ( 0.3) wrack Dulse (Bladder 0.3) wrack Dulse ( 0.3) Marchantia ( 1.5) 0.3) (Dulse ( 0.3) Marchantia ( 1.5) ( 0.3) Marchantia ( 1.5) (b) MOSSES (b) MOSSES FERNS FERNS (b) MOSSES FERNS Spleenwort ( 0.05) Spleenwort ( 0.05) Spleenwort ( 0.05) Funaria ( 1) Funaria ( 1) Funaria ( 1) Hypnum ( 1.5) Bracken ( 0.1) Hypnum ( 1.5) Bracken ( 0.1) Hypnum ( 1.5) Bracken ( 0.1) Hart’s tongue Hart’s ( 0.3)tongue 0.3)tongue (Hart’s ( 0.3) Polytrichum ( 0.75) Polytrichum ( 0.75) Sphagnum ( 0.8) Polytrichum ( 0.75) Male fern ( 0.1) Sphagnum ( 0.8) Male fern ( 0.1) Sphagnum ( 0.8) Male fern ( 0.1) Polypody ( 0.3) Polypody ( 0.3) Figure 1.10 The plant kingdom; plants that do notPolypody ( 0.3) bear seeds 9 9781444176469_IGCSE_Biology_1.indd 9 8/18/14 9:39 PM  1 Characteristics and classification of living organisms CONIFERS FLOWERING PLANTS CONIFERS (a)FLOWERING PLANTS MONOCOTYLEDONS (a) MONOCOTYLEDONS Pine ( 0.004) Pine ( 0.004) Meadow grass ( 0.6) Cocksfoot Meadow grass ( 0.4) ( 0.6) Cocksfoot Iris ( 0.3) ( 0.4) Daffodil ( 0.3) Iris ( 0.3) Daffodil ( 0.3) (b) DICOTYLEDONS (b) DICOTYLEDONS (i) Trees (i) Trees (ii) Shrubs Broom ( 0.03) (ii) Shrubs Spruce Broom ( 0.03) ( 0.004) Spruce ( 0.004) Cypress ( 0.005) Cypress ( 0.005) Horse chestnut ( 0.002) Horse chestnut ( 0.002) (iii) Herbs (iii) Herbs Forget-me-not ( 0.5) Forget-me-not ( 0.5) Buttercup ( 0.5) Buttercup ( 0.5) Cedar ( 0.0035) Poppy ( 0.4) Cedar ( 0.0035) Poppy ( 0.4) Figure 1.11 The plant kingdom; seed-bearing plants 10 9781444176469_IGCSE_Biology_1.indd 10 8/18/14 9:39 PM  Features of organisms The animal kingdom Crustacea Marine crustacea are crabs, prawns, lobsters, shrimps Animals are multicellular organisms whose cells have and barnacles. Freshwater crustacea are water fleas, no cell walls or chloroplasts. Most animals ingest Cyclops, the freshwater shrimp (Gammarus) and the solid food and digest it internally. water louse (Asellus). Woodlice are land-dwelling Animal kingdom crustacea. Some of these crustacea are illustrated in (Only eight groups out of 23 are listed here.) Each Figure 1.8 on page 7. group is called a phylum (plural = phyla). Like all arthropods, crustacea have an exoskeleton and jointed legs. They also have two Coelenterates (sea anemones, jellyfish) pairs of antennae which are sensitive to touch Flatworms and to chemicals, and they have compound eyes. Nematode worms Compound eyes are made up of tens or hundreds Annelids (segmented worms) of separate lenses with light-sensitive cells beneath. Arthropods They are able to form a crude image and are very CLASS sensitive to movement. * Crustacea (crabs, shrimps, water fleas) Typically, crustacea have a pair of jointed limbs Insects on each segment of the body, but those on the Arachnids (spiders and mites) head segments are modified to form antennae Myriapods (centipedes and millipedes) or specialised mouth parts for feeding (see Molluscs (snails, slugs, mussels, octopuses) Figure 1.12). Echinoderms (starfish, sea urchins) second antenna Vertebrates CLASS Fish Amphibia (frogs, toads, newts) Reptiles (lizards, snakes, turtles) thorax compound Birds eye segmented Mammals abdomen first antenna (Only four subgroups out of about 26 are listed.) Insectivores Carnivores claw Rodents Primates *All the organisms which do not have a vertebral column are often referred to as ­invertebrates. Invertebrates are not a natural group, but the term is convenient to use. walking legs Figure 1.12 External features of a crustacean (lobster ×0.2) Arthropods Insects The arthropods include the crustacea, insects, The insects form a very large class of arthropods. centipedes and spiders (see Figure 1.8 on page 7). Bees, butterflies, mosquitoes, houseflies, earwigs, The name arthropod means ‘jointed limbs’, and this is greenfly and beetles are just a few of the subgroups in a feature common to them all. They also have a hard, this class. firm external skeleton, called a cuticle, which encloses Insects have segmented bodies with a firm their bodies. Their bodies are segmented and, exoskeleton, three pairs of jointed legs, compound between the segments, there are flexible joints which eyes and, typically, two pairs of wings. The segments permit movement. In most arthropods, the segments are grouped into distinct head, thorax and abdomen are grouped together to form distinct regions, the regions (see Figure 1.13). head, thorax and abdomen. Table 1.1 outlines the key features of the four classes of arthropod. 11 9781444176469_IGCSE_Biology_1.indd 11 8/18/14 9:39 PM  1 CharaCteristiCs and ClassifiCation of living organisms compound eye one pair of antennae are used in reproduction; the chelicerae are used to pierce their prey and paralyse it with a poison secreted by a gland at the base. There are usually thorax head several pairs of simple eyes. pedipalp wing abdomen position (segmented) three pairs of legs of chelicerae cephalothorax poison sac chelicera (poison fang) Figure 1.13 External features of an insect (greenbottle, ×5). Flies, held on underside midges and mosquitoes have only one pair of wings. of cephalothorax Insects differ from crustacea in having wings, only abdomen one pair of antennae and only three pairs of legs. Figure 1.14 External features of an arachnid (×2.5) There are no limbs on the abdominal segments. The insects have very successfully colonised the Myriapods land. One reason for their success is the relative These are millipedes and centipedes. They have a head impermeability of their cuticles, which prevents and a segmented body which is not obviously divided desiccation even in very hot, dry climates. into thorax and abdomen. There is a pair of legs on each body segment but in the millipede the abdominal Arachnids segments are fused in pairs and it looks as if it has two These are the spiders, scorpions, mites and ticks. pairs of legs per segment (see Figure 1.15). Their bodies are divided into two regions, the As the myriapod grows, additional segments are cephalothorax and the abdomen (see Figure 1.14). formed. The myriapods have one pair of antennae They have four pairs of limbs on the cephalothorax, and simple eyes. Centipedes are carnivorous; two pedipalps and two chelicerae. The pedipalps millipedes feed on vegetable matter. up to 70 abdominal segments fused in pairs thorax (four segments) } one pair of legs simple eye on each thoracic two pairs of legs on each segment paired abdominal segment antenna head Figure 1.15 External features of a myriapod (×2.5) Table 1.1 Key features of the four classes of arthropods Insects Arachnids Crustacea Myriapods e.g. dragonfly, wasp e.g. spider, mite e.g. crab, woodlouse e.g. centipede, millipede three pairs of legs four pairs of legs five or more pairs of legs ten or more pairs of legs (usually one pair per segment) body divided into head, thorax body divided into body divided into body not obviously divided and abdomen cephalothorax and abdomen cephalothorax and abdomen into thorax and abdomen one pair of antennae two pairs of antennae one pair of antennae one pair of compound eyes several pairs of simple eyes one pair of compound eyes simple eyes usually have two pairs of chelicerae for biting and exoskeleton often calcified to wings poisoning prey form a carapace (hard) 12 9781444176469_IGCSE_Biology_1.indd 12 8/18/14 9:39 PM  features of organisms Vertebrates Fish Vertebrates are animals which have a vertebral Fish are poikilothermic (cold blooded) vertebrates. column. The vertebral column is sometimes called Many of them have a smooth, streamlined shape the spinal column or just the spine and consists of which offers minimal resistance to the water through a chain of cylindrical bones (vertebrae) joined end which they move (see Figure 1.16). Their bodies are to end. covered with overlapping scales and they have fins Each vertebra carries an arch of bone on its dorsal which play a part in movement. (upper) surface. This arch protects the spinal cord Fish breathe by means of filamentous gills which (see Chapter 14), which runs most of the length of are protected by a bony plate, the operculum. the vertebral column. The front end of the spinal Fish reproduce sexually but fertilisation usually cord is expanded to form a brain which is enclosed takes place externally; the female lays eggs and the and protected by the skull. male sheds sperms on them after they have been laid. The skull carries a pair of jaws which, in most scale dorsal fin tail fin vertebrates, have rows of teeth. The five classes of vertebrates are fish, amphibia, reptiles, birds and mammals. Table 1.2 summarises the key features of these classes. Body temperature Fish, amphibia and reptiles are often referred to as operculum pelvic fin pectoral anal fin ‘cold-blooded’. This is a misleading term. A fish in a covering gills fin tropical lagoon or a lizard basking in the sun will have Figure 1.16 Herring (Clupea, ×0.3) warm blood. The point is that these animals have a variable body temperature which, to some extent, Amphibia depends on the temperature of their surroundings. Amphibia are poikilothermic (cold blooded) Reptiles, for example, may control their temperature vertebrates with four limbs and no scales. The class by moving into sunlight or retreating into shade but includes frogs, toads and newts. The name, amphibian, there is no internal regulatory mechanism. means ‘double life’ and refers to the fact that the So-called ‘warm-blooded’ animals, for the most organism spends part of its life in water and part on part, have a body temperature higher than that of the land. In fact, most frogs, toads and newts spend their surroundings. The main difference, however, is much of their time on the land, in moist situations, that these temperatures are kept more