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8th Edition of Biology by Solomon Berg Martin.

8th Edition of Biology by Solomon Berg Martin.

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    Biology, Solomon Berg Martin 8th Edition Biology, Solomon Berg Martin 8th Edition Document Transcript

    • Biology EIGHTH EDITIONEldra P. Solomon Linda R. Berg Diana W. MartinUniversity of South Florida St. Petersburg College Rutgers University Australia • Canada • Mexico • Singapore • Spain • United Kingdom • United States
    • Biology, Eighth Edition Eldra P. Solomon, Linda R. Berg, and Diana W. MartinPublisher: Peter Adams Print Buyer: Judy InouyeDevelopment Editor: Suzannah Alexander Permissions Editor: Bob KauserAssistant Editor: Lauren Oliveira Production Service: Jamie Armstrong, Newgen–AustinEditorial Assistant: Kate Franco Text Designer: John WalkerTechnology Project Manager: Keli Amann Photo Researcher: Kathleen OlsonMarketing Manager: Kara Kindstrom Copy Editor: Cynthia LindlofMarketing Assistant: Catie Ronquillo Illustrator: Precision Graphics, Newgen–AustinMarketing Communications Manager: Bryan Vann Cover Designer: Robin TerraProject Manager, Editorial Production: Cheryll Linthicum, Cover Image: Gail Shumway/Taxi/Getty Images Jennifer Risden Cover Printer: Quebecor World/VersaillesCreative Director: Rob Hugel Compositor: Newgen–AustinArt Director: Lee Friedman Printer: Quebecor World/Versailles© 2008, 2005 Thomson Brooks/Cole, a part of The Thomson Thomson Higher EducationCorporation. Thomson, the Star logo, and Brooks/Cole are trade- 10 Davis Drivemarks used herein under license. Belmont, CA 94002-3098 USAALL RIGHTS RESERVED. No part of this work covered by thecopyright hereon may be reproduced or used in any form or by any Library of Congress Control Number: 2006924995means—graphic, electronic, or mechanical, including photocopy-ing, recording, taping, web distribution, information storage and Student Edition: ISBN 13: 978-0-495-10705-7retrieval systems, or in any other manner—without the written per-mission of the publisher. Student Edition: ISBN 10: 0-495-10705-0Printed in the United States of America Volume 1: ISBN 13: 978-0-495-30978-91 2 3 4 5 6 7 10 09 08 07 06 Volume 1: ISBN 10: 0-495-30978-8 For more information about our products, contact us at: Thomson Learning Academic Resource Center 1-800-423-0563 For permission to use material from this text or product, submit a request online at http://www.thomsonrights.com. Any additional questions about permissions can be submitted by e-mail to thomsonrights@thomson.com.ExamView® and ExamView Pro® are registered trademarks ofFSCreations, Inc. Windows is a registered trademark of the Micro-soft Corporation used herein under license. Macintosh and PowerMacintosh are registered trademarks of Apple Computer, Inc. Usedherein under license.
    • DEDICATIONTo our families, friends, and colleagues who gave freely of theirlove, support, knowledge, and time as we prepared this eighthedition of BiologyEspecially toRabbi Theodore and Freda BrodAlan and JenniferChuck and Margaret
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    • ABOUT THE AUTHORSELDRA P. SOLOMON has written LINDA R. BERG is an award-winning DIANA W. MARTIN is the Directorseveral leading college-level textbooks teacher and textbook author. She re- of General Biology, Division of Lifein biology and in human anatomy and ceived a B.S. in science education, an Sciences, at Rutgers University, Newphysiology. Her books have been trans- M.S. in botany, and a Ph.D. in plant Brunswick Campus. She received anlated into more than 10 languages. physiology from the University of Mary- M.S. at Florida State University, whereDr. Solomon earned an M.S. from the land. Her research focused on the evo- she studied the chromosomes of relatedUniversity of Florida and an M.A. and lutionary implications of steroid biosyn- plant species to understand their evolu-Ph.D. from the University of South thetic pathways in various organisms. tionary relationships. She earned a Ph.D.Florida. Dr. Solomon taught biology and Dr. Berg taught at the University of at the University of Texas at Austin,nursing students for more than 20 years. Maryland at College Park for 17 years where she studied the genetics of theShe is adjunct professor and member of and at St. Petersburg College in Florida fruit fly, Drosophila melanogaster, andthe Graduate Faculty of the University for 8 years. During her career, she taught then conducted postdoctoral researchof South Florida. introductory courses in biology, botany, at Princeton University. She has taught In addition to being a biologist and and environmental science to thousands general biology and other courses atscience author, Dr. Solomon is a bio- of students. At the University of Mary- Rutgers for more than 20 years and haspsychologist with a special interest in the land, she received numerous teaching been involved in writing textbooks sinceneurophysiology of traumatic experience. and service awards. Dr. Berg is also the 1988. She is immensely grateful that herHer research has focused on the relation- recipient of many national and regional decision to study biology in college hasships among stress, emotions, and health awards, including the National Science led to a career that allows her many waysand on post-traumatic stress disorder. Teachers Association Award for Innova- to share her excitement about all aspects Dr. Solomon has presented her work in tions in College Science Teaching, the of biology.plenary sessions and scientific meetings at Nation’s Capital Area Disabled Studentmany national and international confer- Services Award, and the Washingtonences. She has been profiled more than Academy of Sciences Award in Univer-20 times in leading publications, includ- sity Science Teaching.ing Who’s Who in America, Who’s Who During her career as a professionalin Science and Engineering, Who’s Who in science writer, Dr. Berg has authored orMedicine and Healthcare, Who’s Who in co-authored several leading college sci-American Education, Who’s Who of Ameri- ence textbooks. Her writing reflects hercan Women, and Who’s Who in the World. teaching style and love of science.
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    • Brief ContentsPreface xxvii 14 Gene Regulation 304To the Student xxxiii 15 DNA Technology and Genomics 322 16 The Human Genome 346 17 Developmental Genetics 368Part 1 THE ORGANIZATION OF LIFE 1 1 A View of Life 1 2 Atoms and Molecules: The Chemical Basis Part 4 THE CONTINUITY OF LIFE: of Life 25 EVOLUTION 390 3 The Chemistry of Life: Organic Compounds 45 18 Introduction to Darwinian Evolution 390 4 Organization of the Cell 73 19 Evolutionary Change in Populations 412 5 Biological Membranes 106 20 Speciation and Macroevolution 428 6 Cell Communication 134 21 The Origin and Evolutionary History of Life 447 22 The Evolution of Primates 466Part 2 ENERGY TRANSFER THROUGH LIVING SYSTEMS 152 7 Energy and Metabolism 152 Part 5 THE DIVERSITY OF LIFE 482 8 How Cells Make ATP: Energy-Releasing 23 Understanding Diversity: Systematics 482 Pathways 171 24 Viruses and Prokaryotes 500 9 Photosynthesis: Capturing Energy 191 25 Protists 530 26 Kingdom Fungi 555 27 The Plant Kingdom: Seedless Plants 581Part 3 THE CONTINUITY OF LIFE: 28 The Plant Kingdom: Seed Plants 600 GENETICS 211 29 The Animal Kingdom: An Introduction 10 Chromosomes, Mitosis, and Meiosis 211 to Animal Diversity 619 11 The Basic Principles of Heredity 234 30 The Animal Kingdom: The Protostomes 640 12 DNA: The Carrier of Genetic Information 260 31 The Animal Kingdom: The Deuterostomes 667 13 Gene Expression 279 vii
    • Part 6 STRUCTURE AND LIFE PROCESSES 48 Endocrine Regulation 1028 IN PLANTS 698 49 Reproduction 1051 32 Plant Structure, Growth, and 50 Animal Development 1080 Differentiation 698 51 Animal Behavior 1101 33 Leaf Structure and Function 715 34 Stems and Transport in Vascular Plants 731 35 Roots and Mineral Nutrition 748 Part 8 THE INTERACTIONS OF LIFE: 36 Reproduction in Flowering Plants 767 ECOLOGY 1126 37 Plant Growth and Development 789 52 Introduction to Ecology: Population Ecology 1126 53 Community Ecology 1146Part 7 STRUCTURE AND LIFE PROCESSES 54 Ecosystems and the Biosphere 1166 IN ANIMALS 807 55 Ecology and the Geography of Life 1189 38 Animal Structure and Function: 56 Global Environmental Issues 1212 An Introduction 807 39 Protection, Support, and Movement 827 Appendix A Periodic Table of the Elements A-1 40 Neural Signaling 845 Appendix B Classification of Organisms A-2 41 Neural Regulation 865 Appendix C Understanding Biological Terms A-6 42 Sensory Systems 893 Appendix D Abbreviations A-9 43 Internal Transport 919 Appendix E Answers to Test Your Understanding Questions A-11 44 The Immune System: Internal Defense 944 Glossary G-1 45 Gas Exchange 970 Index I-1 46 Processing Food and Nutrition 989 47 Osmoregulation and Disposal of Metabolic Wastes 1011viii Brief Contents www.thomsonedu.com/biology/solomon
    • ContentsPart 1 THE ORGANIZATION OF LIFE 1 Scientists interpret the results of experiments and make conclusions 18 A theory is supported by tested hypotheses 20 1 A VIEW OF LIFE 1 Many hypotheses cannot be tested by direct experiment 20 Paradigm shifts allow new discoveries 21 Three Basic Themes 2 Systems biology integrates different levels of information 21 Characteristics of Life 2 Science has ethical dimensions 21 Organisms are composed of cells 2 Organisms grow and develop 3 Organisms regulate their metabolic processes 3 Organisms respond to stimuli 4 Organisms reproduce 5 2 ATOMS AND MOLECULES: Populations evolve and become adapted THE CHEMICAL BASIS OF LIFE 25 to the environment 5 Elements and Atoms 26 Levels of Biological Organization 6 An atom is uniquely identified by its number of protons 27 Organisms have several levels of organization 6 Protons plus neutrons determine atomic mass 28 Several levels of ecological organization can be identified 6 Isotopes of an element differ in number of neutrons 28 Information Transfer 6 Electrons move in orbitals corresponding to energy levels 29 DNA transmits information from one generation Chemical Reactions 29 to the next 6 Atoms form compounds and molecules 29 Information is transmitted by chemical and electrical Simplest, molecular, and structural chemical formulas signals 8 give different information 30 Evolution: The Basic Unifying Concept One mole of any substance contains the same number of Biology 9 of units 31 Biologists use a binomial system for naming organisms 9 Chemical equations describe chemical reactions 31 Taxonomic classification is hierarchical 9 Chemical Bonds 31 The tree of life includes three domains and six kingdoms 11 In covalent bonds electrons are shared 31 Species adapt in response to changes in their environment 11 Ionic bonds form between cations and anions 33 Natural selection is an important mechanism by which Hydrogen bonds are weak attractions 35 evolution proceeds 11 van der Waals interactions are weak forces 36 Populations evolve as a result of selective pressures from changes in their environment 13 Redox Reactions 36 The Energy for Life 14 Water 36 The Process of Science 15 Hydrogen bonds form between water molecules 37 Science requires systematic thought processes 16 Water molecules interact with hydrophilic substances by hydrogen bonding 37 Scientists make careful observations and ask critical questions 16 Water helps maintain a stable temperature 38 Chance often plays a role in scientific discovery 16 Acids, Bases, and Salts 39 A hypothesis is a testable statement 17 pH is a convenient measure of acidity 40 Many predictions can be tested by experiment 17 Buffers minimize pH change 40 Researchers must avoid bias 18 An acid and a base react to form a salt 41 ix
    • 3 THE CHEMISTRY OF LIFE: F o c u s O n : Acetabularia and the Control of Cell ORGANIC COMPOUNDS 45 Activities 86 Carbon Atoms and Molecules 46 Organelles in the Cytoplasm 88 Isomers have the same molecular formula but different Ribosomes manufacture proteins 89 structures 47 The endoplasmic reticulum is a network of internal Functional groups change the properties of organic membranes 90 molecules 48 The Golgi complex processes, sorts, and modifies proteins 91 Many biological molecules are polymers 50 Lysosomes are compartments for digestion 92 Vacuoles are large, fluid-filled sacs with a variety Carbohydrates 50 of functions 93 Monosaccharides are simple sugars 51 Peroxisomes metabolize small organic compounds 94 Disaccharides consist of two monosaccharide units 52 Mitochondria and chloroplasts are energy-converting Polysaccharides can store energy or provide structure 52 organelles 94 Some modified and complex carbohydrates have special Mitochondria make ATP through cellular respiration 94 roles 54 Chloroplasts convert light energy to chemical energy Lipids 56 through photosynthesis 96 Triacylglycerol is formed from glycerol and three fatty The Cytoskeleton 97 acids 56 Microtubules are hollow cylinders 97 Saturated and unsaturated fatty acids differ in physical Microfilaments consist of intertwined strings of actin 99 properties 56 Intermediate filaments help stabilize cell shape 101 Phospholipids are components of cell membranes 57 Carotenoids and many other pigments are derived Cell Coverings 102 from isoprene units 57 Steroids contain four rings of carbon atoms 57 Some chemical mediators are lipids 58 5 BIOLOGICAL MEMBRANES 106 Proteins 59 Amino acids are the subunits of proteins 62 The Structure of Biological Membranes 107 Proteins have four levels of organization 63 Phospholipids form bilayers in water 107 The amino acid sequence of a protein determines its Current data support a fluid mosaic model of membrane conformation 66 structure 108 Biological membranes are two-dimensional fluids 109 Nucleic Acids 67 Biological membranes fuse and form closed vesicles 110 Some nucleotides are important in energy transfers and other Membrane proteins include integral and peripheral cell functions 68 proteins 110 Identifying Biological Molecules 70 Proteins are oriented asymmetrically across the bilayer 111 Membrane proteins function in transport, in information transfer, and as enzymes 113 Passage of Materials through Cell 4 ORGANIZATION OF THE CELL 73 Membranes 114 The Cell Theory 74 Biological membranes present a barrier to polar molecules 115 Cell Organization and Size 74 Transport proteins transfer molecules across The organization of all cells is basically similar 74 membranes 115 Cell size is limited 74 Cell size and shape are related to function 76 Passive Transport 115 Diffusion occurs down a concentration gradient 116 Methods for Studying Cells 76 Osmosis is diffusion of water across a selectively permeable Light microscopes are used to study stained membrane 116 or living cells 76 Facilitated diffusion occurs down a concentration Electron microscopes provide a high-resolution image that can gradient 118 be greatly magnified 78 Biologists use biochemical techniques to study cell Active Transport 120 components 78 Active transport systems “pump” substances against their concentration gradients 120 Prokaryotic and Eukaryotic Cells 80 Carrier proteins can transport one or two solutes 122 Cell Membranes 81 Cotransport systems indirectly provide energy The Cell Nucleus 84 for active transport 122x Contents www.thomsonedu.com/biology/solomon
    • Exocytosis and Endocytosis 123 Free energy decreases during an exergonic reaction 155 In exocytosis, vesicles export large molecules 123 Free energy increases during an endergonic reaction 156 In endocytosis, the cell imports materials 123 Diffusion is an exergonic process 156 Cell Junctions 127 Free-energy changes depend on the concentrations of reactants and products 156 Anchoring junctions connect cells of an epithelial sheet 127 Cells drive endergonic reactions by coupling them Tight junctions seal off intercellular spaces between some to exergonic reactions 157 animal cells 127 Gap junctions allow the transfer of small molecules ATP, the Energy Currency of the Cell 157 and ions 128 ATP donates energy through the transfer Plasmodesmata allow certain molecules and ions to move of a phosphate group 158 between plant cells 129 ATP links exergonic and endergonic reactions 158 The cell maintains a very high ratio of ATP to ADP 159 Energy Transfer in Redox Reactions 159 6 CELL COMMUNICATION 134 Most electron carriers transfer hydrogen atoms 159 Cell Signaling: An Overview 135 Enzymes 160 Sending Signals 136 All reactions have a required energy of activation 161 Reception 137 An enzyme lowers a reaction’s activation energy 162 Cells regulate reception 138 An enzyme works by forming an enzyme–substrate Three types of receptors occur on the cell surface 138 complex 162 Some receptors are intracellular 140 Enzymes are specific 163 Many enzymes require cofactors 163 Signal Transduction 140 Enzymes are most effective at optimal conditions 163 Ion channel–linked receptors open or close channels 140 Enzymes are organized into teams in metabolic pathways 164 G protein–linked receptors initiate signal transduction 141 The cell regulates enzymatic activity 165 Second messengers are intracellular signaling agents 141 Enzymes are inhibited by certain chemical agents 166 Enzyme-linked receptors function directly 144 Some drugs are enzyme inhibitors 167 Many activated intracellular receptors are transcription factors 144 Scaffolding proteins increase efficiency 145 Signals can be transmitted in more than one direction 145 8 HOW CELLS MAKE ATP: ENERGY- Responses to Signals 145 RELEASING PATHWAYS 171 The response to a signal is amplified 146 Redox Reactions 172 Signals must be terminated 147 The Four Stages of Aerobic Respiration 173 Evolution of Cell Communication 147 In glycolysis, glucose yields two pyruvates 174 Pyruvate is converted to acetyl CoA 175 The citric acid cycle oxidizes acetyl CoA 178 The electron transport chain is coupled to ATP synthesis 179 Aerobic respiration of one glucose yields a maximumPart 2 ENERGY TRANSFER THROUGH of 36 to 38 ATPs 183 LIVING SYSTEMS 152 Cells regulate aerobic respiration 185 Energy Yield of Nutrients Other Than Glucose 185 7 ENERGY AND METABOLISM 152 Anaerobic Respiration and Fermentation 186 Biological Work 153 Alcohol fermentation and lactate fermentation are Organisms carry out conversions between potential energy inefficient 187 and kinetic energy 153 The Laws of Thermodynamics 154 The total energy in the universe does not change 154 9 PHOTOSYNTHESIS: The entropy of the universe is increasing 154 CAPTURING ENERGY 191 Energy and Metabolism 155 Light 192 Enthalpy is the total potential energy of a system 155 Chloroplasts 193 Free energy is available to do cell work 155 Chlorophyll is found in the thylakoid membrane 193 Chemical reactions involve changes in free energy 155 Chlorophyll is the main photosynthetic pigment 194 Contents xi
    • Overview of Photosynthesis 196 Prophase I includes synapsis and crossing-over 224 ATP and NADPH are the products of the light-dependent During meiosis I, homologous chromosomes separate 225 reactions: An overview 197 Chromatids separate in meiosis II 225 Carbohydrates are produced during the carbon fixation Mitosis and meiosis lead to contrasting outcomes 225 reactions: An overview 197 The timing of meiosis in the life cycle varies among The Light-Dependent Reactions 198 species 228 Photosystems I and II each consist of a reaction center and multiple antenna complexes 198 Noncyclic electron transport produces ATP and NADPH 198 Cyclic electron transport produces ATP but no NADPH 200 11 THE BASIC PRINCIPLES ATP synthesis occurs by chemiosmosis 200 OF HEREDITY 234 The Carbon Fixation Reactions 202 Mendel’s Principles of Inheritance 235 Most plants use the Calvin cycle to fix carbon 202 Alleles separate before gametes are formed: the principle Photorespiration reduces photosynthetic efficiency 204 of segregation 236 The initial carbon fixation step differs in C4 plants and in Alleles occupy corresponding loci on homologous CAM plants 204 chromosomes 238 Metabolic Diversity 206 A monohybrid cross involves individuals with different alleles of a given locus 238 Photosynthesis in Plants and in the Environment 207 A dihybrid cross involves individuals that have different alleles at two loci 240 Alleles on nonhomologous chromosomes are randomly distributed into gametes: the principle of independent assortment 241 Recognition of Mendel’s work came during the earlyPart 3 THE CONTINUITY OF LIFE: 20th century 242 GENETICS 211 Using Probability to Predict Mendelian Inheritance 243 The rules of probability can be applied to a variety 10 CHROMOSOMES, MITOSIS, of calculations 244 AND MEIOSIS 211 F o c u s O n : Solving Genetics Problems 245 Eukaryotic Chromosomes 212 Inheritance and Chromosomes 246 DNA is organized into informational units called genes 212 Linked genes do not assort independently 246 DNA is packaged in a highly organized way in Calculating the frequency of crossing-over reveals the linear chromosomes 212 order of linked genes on a chromosome 247 Chromosome number and informational content differ among Sex is generally determined by sex chromosomes 248 species 214 Extensions of Mendelian Genetics 252 The Cell Cycle and Mitosis 215 Dominance is not always complete 252 Chromosomes duplicate during interphase 215 Multiple alleles for a locus may exist in a population 253 During prophase, duplicated chromosomes become visible with the microscope 216 A single gene may affect multiple aspects of the phenotype 253 Prometaphase begins when the nuclear envelope breaks down 218 Alleles of different loci may interact to produce a phenotype 254 Duplicated chromosomes line up on the midplane during metaphase 218 Polygenes act additively to produce a phenotype 255 During anaphase, chromosomes move toward the poles 219 Genes interact with the environment to shape phenotype 256 During telophase, two separate nuclei form 220 Cytokinesis forms two separate daughter cells 220 Mitosis produces two cells genetically identical to the parent cell 221 Lacking nuclei, prokaryotes divide by binary fission 221 12 DNA: THE CARRIER OF GENETIC Regulation of the Cell Cycle 221 INFORMATION 260 Sexual Reproduction and Meiosis 223 Evidence of DNA as the Hereditary Material 261 Meiosis produces haploid cells with unique gene DNA is the transforming principle in bacteria 261 combinations 224 DNA is the genetic material in certain viruses 263xii Contents www.thomsonedu.com/biology/solomon
    • The Structure of DNA 263 Some mutations involve larger DNA segments 298 Nucleotides can be covalently linked in any order Mutations have various causes 300 to form long polymers 263 DNA is made of two polynucleotide chains intertwined to form a double helix 264 In double-stranded DNA, hydrogen bonds form between A and T and between G and C 265 14 GENE REGULATION 304 DNA Replication 266 Gene Regulation in Bacteria and Eukaryotes: Meselson and Stahl verified the mechanism An Overview 305 of semiconservative replication 266 Gene Regulation in Bacteria 306 Semiconservative replication explains the perpetuation Operons in bacteria facilitate the coordinated control of mutations 268 of functionally related genes 306 DNA replication requires protein “machinery” 270 Some posttranscriptional regulation occurs in bacteria 309 Enzymes proofread and repair errors in DNA 274 Gene Regulation in Eukaryotic Cells 312 Telomeres cap eukaryotic chromosome ends 275 Eukaryotic transcription is controlled at many sites and by many different regulatory molecules 313 The mRNAs of eukaryotes have many types of posttranscriptional control 31713 GENE EXPRESSION 279 Posttranslational chemical modifications may alter the activity of eukaryotic proteins 318 Discovery of the Gene–Protein Relationship 280 Beadle and Tatum proposed the one-gene, one-enzyme hypothesis 280 Information Flow from DNA to Protein: An Overview 282 15 DNA TECHNOLOGY DNA is transcribed to form RNA 282 AND GENOMICS 322 RNA is translated to form a polypeptide 282 DNA Cloning 323 Biologists cracked the genetic code in the 1960s 283 Restriction enzymes are “molecular scissors” 323 Transcription 285 Recombinant DNA forms when DNA is spliced into The synthesis of mRNA includes initiation, elongation, a vector 324 and termination 286 DNA can be cloned inside cells 324 Messenger RNA contains base sequences that do not directly The polymerase chain reaction is a technique for amplifying code for protein 288 DNA in vitro 328 Translation 288 DNA Analysis 330 An amino acid is attached to tRNA before incorporation Gel electrophoresis is used for separating into a polypeptide 288 macromolecules 330 The components of the translational machinery come together DNA, RNA, and protein blots detect specific at the ribosomes 289 fragments 331 Variations in Gene Expression in Different Restriction fragment length polymorphisms are a measure Organisms 292 of genetic relationships 331 Transcription and translation are coupled in prokaryotes 293 One way to characterize DNA is to determine its sequence of nucleotides 331 Eukaryotic mRNA is modified after transcription and before translation 293 Genomics 333 Both noncoding and coding sequences are transcribed Identifying protein-coding genes is useful for research from eukaryotic genes 294 and for medical applications 334 Several kinds of eukaryotic RNA have a role in gene One way to study gene function is to silence genes one at expression 296 a time 335 The definition of a gene has evolved as biologists have learned DNA microarrays are a powerful tool for studying how genes more about genes 297 interact 335 The usual direction of information flow has exceptions 297 The Human Genome Project stimulated studies on the genome sequences of other species 337 Mutations 298 Base-substitution mutations result from the replacement Applications of DNA Technologies 338 of one base pair by another 298 DNA technology has revolutionized medicine Frameshift mutations result from the insertion or deletion and pharmacology 338 of base pairs 298 DNA fingerprinting has numerous applications 339 Contents xiii
    • Transgenic organisms have incorporated foreign DNA The first cloned mammal was a sheep 371 into their cells 340 Stem cells divide and give rise to differentiated cells 372 DNA Technology Has Raised Safety The Genetic Control of Development 374 Concerns 342 A variety of model organisms provide insights into basic biological processes 374 Many examples of genes that control development have been identified in the fruit fly Drosophila 375 16 THE HUMAN GENOME 346 Caenorhabditis elegans has a relatively rigid developmental pattern 380 Studying Human Genetics 347 The mouse is a model for mammalian development 383 Human chromosomes are studied by karyotyping 347 Arabidopsis is a model for studying plant development, Family pedigrees help identify certain inherited including transcription factors 385 conditions 348 The Human Genome Project sequenced the DNA Cancer and Cell Development 386 on all human chromosomes 349 Comparative genomics has revealed several hundred DNA segments that are identical in both mouse and human genomes 350 Researchers use mouse models to study human genetic diseases 350 Part 4 THE CONTINUITY OF LIFE: Abnormalities in Chromosome Number and EVOLUTION 390 Structure 351 Down syndrome is usually caused by trisomy 21 353 Most sex chromosome aneuploidies are less severe than 18 INTRODUCTION TO DARWINIAN autosomal aneuploidies 354 EVOLUTION 390 Abnormalities in chromosome structure cause certain disorders 354 What Is Evolution? 391 Genetic Diseases Caused by Single-Gene Pre-Darwinian Ideas about Evolution 391 Mutations 356 Darwin and Evolution 392 Many genetic diseases are inherited as autosomal recessive Darwin proposed that evolution occurs by natural traits 356 selection 394 Some genetic diseases are inherited as autosomal dominant The modern synthesis combines Darwin’s theory traits 358 with genetics 394 Some genetic diseases are inherited as X-linked recessive Biologists study the effect of chance on evolution 395 traits 359 Evidence for Evolution 396 Gene Therapy 360 The fossil record provides strong evidence for evolution 396 Gene therapy programs are carefully scrutinized 360 Comparative anatomy of related species demonstrates Genetic Testing and Counseling 361 similarities in their structures 400 Prenatal diagnosis detects chromosome abnormalities The distribution of plants and animals supports and gene defects 361 evolution 402 Genetic screening searches for genotypes or karyotypes 362 Developmental biology helps unravel evolutionary patterns 404 Genetic counselors educate people about genetic diseases 363 Molecular comparisons among organisms provide evidence Human Genetics, Society, and Ethics 363 for evolution 405 Genetic discrimination provokes heated debate 364 Evolutionary hypotheses are tested experimentally 408 Many ethical issues related to human genetics must be addressed 364 19 EVOLUTIONARY CHANGE IN POPULATIONS 412 17 DEVELOPMENTAL GENETICS 368 Genotype, Phenotype, and Allele Cell Differentiation and Nuclear Equivalence 369 Frequencies 413 Most cell differences are due to differential gene The Hardy–Weinberg Principle 413 expression 369 Genetic equilibrium occurs if certain conditions are met 415 A totipotent nucleus contains all the instructions Human MN blood groups are a valuable illustration of the for development 370 Hardy–Weinberg principle 415xiv Contents www.thomsonedu.com/biology/solomon
    • Microevolution 416 Biological evolution began with the first cells 452 Nonrandom mating changes genotype frequencies 416 The first cells were probably heterotrophic 452 Mutation increases variation within a population 417 Aerobes appeared after oxygen increased in the In genetic drift, random events change allele frequencies 417 atmosphere 453 Gene flow generally increases variation within a Eukaryotic cells descended from prokaryotic cells 453 population 418 The History of Life 455 Natural selection changes allele frequencies in a way that Rocks from the Ediacaran period contain fossils of cells and increases adaptation 418 simple animals 455 Genetic Variation in Populations 421 A diversity of organisms evolved during the Paleozoic era 455 Genetic polymorphism exists among alleles and the proteins Dinosaurs and other reptiles dominated the Mesozoic era 459 for which they code 421 The Cenozoic era is the Age of Mammals 461 Balanced polymorphism exists for long periods 422 Neutral variation may give no selective advantage or F o c u s O n : The Origin of Flight in Birds 462 disadvantage 424 Populations in different geographic areas often exhibit genetic adaptations to local environments 425 22 THE EVOLUTION OF PRIMATES 466 Primate Adaptations 467 Primate Classification 46820 SPECIATION AND Suborder Anthropoidea includes monkeys, apes, and MACROEVOLUTION 428 humans 469 What Is a Species? 429 Apes are our closest living relatives 469 Reproductive Isolation 430 Hominid Evolution 471 Prezygotic barriers interfere with fertilization 430 The earliest hominids may have lived 6 mya to 7 mya 473 Postzygotic barriers prevent gene flow when fertilization Australopithecines are the immediate ancestors of genus occurs 431 Homo 474 Biologists are discovering the genetic basis of isolating Homo habilis is the oldest member of genus Homo 474 mechanisms 432 Homo erectus apparently evolved from Homo habilis 475 Speciation 432 Archaic Homo sapiens appeared between 400,000 and 200,000 years ago 475 Long physical isolation and different selective pressures result in allopatric speciation 433 Neandertals appeared approximately 230,000 years ago 475 Two populations diverge in the same physical location by F o c u s O n : The Smallest Humans 476 sympatric speciation 434 Biologists debate the origin of modern Homo sapiens 477 Reproductive isolation breaks down in hybrid zones 437 Cultural Change 478 The Rate of Evolutionary Change 438 Development of agriculture resulted in a more dependable Macroevolution 439 food supply 478 Evolutionary novelties originate through modifications of Cultural evolution has had a profound impact on the pre-existing structures 439 biosphere 479 Adaptive radiation is the diversification of an ancestral species into many species 440 Extinction is an important aspect of evolution 442 Is microevolution related to speciation and macroevolution? 444 Part 5 THE DIVERSITY OF LIFE 48221 THE ORIGIN AND EVOLUTIONARY 23 UNDERSTANDING DIVERSITY: HISTORY OF LIFE 447 SYSTEMATICS 482 Chemical Evolution on Early Earth 448 Classifying Organisms 483 Organic molecules formed on primitive Earth 449 Organisms are named using a binomial system 483 The First Cells 450 Each taxonomic level is more general than the one Molecular reproduction was a crucial step in the origin below it 484 of cells 450 Biologists are moving away from Linnaean categories 484 Contents xv
    • Determining the Major Branches in the Tree The Two Prokaryote Domains 518 of Life 484 Some archaea survive in harsh environments 519 Reconstructing Phylogeny 487 Bacteria are the most familiar prokaryotes 520 Homologous structures are important in determining Impact of Prokaryotes 520 evolutionary relationships 489 Some prokaryotes cause disease 523 Shared derived characters provide clues about phylogeny 489 Prokaryotes are used in many commercial processes 526 Biologists carefully choose taxonomic criteria 490 Molecular homologies help clarify phylogeny 491 Taxa are grouped based on their evolutionary relationships 492 25 PROTISTS 530 Constructing Phylogenetic Trees 493 Introduction to the Protists 531 Outgroup analysis is used in constructing and interpreting Evolution of the Eukaryotes 531 cladograms 493 Mitochondria and chloroplasts probably originated A cladogram is constructed by considering shared derived from endosymbionts 532 characters 494 A consensus is emerging in eukaryote classification 532 In a cladogram each branch point represents a major evolutionary step 496 Representative Protists 534 Systematists use the principle of parsimony to make Excavates are anaerobic zooflagellates 534 decisions 497 Discicristates include euglenoids and trypanosomes 536 Alveolates have flattened vesicles under the plasma membrane 537 Motile cells of heterokonts are biflagellate 540 24 VIRUSES AND PROKARYOTES 500 Red algae, green algae, and land plants are collectively classified Viruses 501 as plants 545 A virus consists of nucleic acid surrounded by a protein Cercozoa are amoeboid cells enclosed in shells 546 coat 501 Amoebozoa have lobose pseudopodia 547 Viruses may have evolved from cells 502 Opisthokonts include choanoflagellates, fungi, The International Committee on Taxonomy of Viruses and animals 551 classifies viruses 502 Bacteriophages are viruses that attack bacteria 503 Viruses reproduce only inside host cells 503 26 KINGDOM FUNGI 555 Lytic reproductive cycles destroy host cells 503 Characteristics of Fungi 556 Temperate viruses integrate their DNA into the host DNA 503 Fungi absorb food from the environment 556 Many viruses infect vertebrates 505 Fungi have cell walls that contain chitin 556 Most fungi have a filamentous body plan 556F o c u s O n : Influenza and Other Emerging and Fungi reproduce by spores 556 Re-emerging Diseases 506 Fungal Diversity 558 Some viruses infect plant cells 510 Fungi are assigned to the opisthokont clade 558 Viroids and Prions 510 Diverse groups of fungi have evolved 560 Viroids are the smallest known pathogens 510 Chytrids have flagellate spores 560 Prions are protein particles 511 Zygomycetes reproduce sexually by forming zygospores 561 Prokaryotes 512 Glomeromycetes are symbionts with plant roots 565 Prokaryotes have several common shapes 512 Ascomycetes reproduce sexually by forming ascospores 566 Prokaryotic cells lack membrane-enclosed organelles 512 Basidiomycetes reproduce sexually by forming A cell wall typically covers the cell surface 512 basidiospores 568 Many types of prokaryotes are motile 513 Ecological Importance of Fungi 570 Prokaryotes have a circular DNA molecule 514 Fungi form symbiotic relationships with some animals 570 Most prokaryotes reproduce by binary fission 514 Mycorrhizae are symbiotic relationships between fungi Bacteria transfer genetic information 514 and plant roots 570 Evolution proceeds rapidly in bacterial populations 516 Lichens are symbiotic relationships between a fungus Some bacteria form endospores 516 and a photoautotroph 572 Many bacteria form biofilms 516 Economic, Biological, and Medical Impact Metabolic diversity has evolved among prokaryotes 517 of Fungi 574 Most prokaryotes require oxygen 517 Fungi provide beverages and food 574xvi Contents www.thomsonedu.com/biology/solomon
    • Fungi are important to modern biology and medicine 574 The Evolution of Seed Plants 614 Some fungi cause animal diseases 576 Our understanding of the evolution of flowering plants has Fungi cause many important plant diseases 576 made great progress in recent years 614 29 THE ANIMAL KINGDOM: 27 THE PLANT KINGDOM: AN INTRODUCTION TO SEEDLESS PLANTS 581 ANIMAL DIVERSITY 619 Adaptations of Plants 582 Animal Characters 620 The plant life cycle alternates haploid and diploid Adaptations to Habitats 620 generations 582 Marine habitats offer many advantages 620 Four major groups of plants evolved 583 Some animals are adapted to freshwater habitats 621 Bryophytes 584 Terrestrial living requires major adaptations 621 Moss gametophytes are differentiated into “leaves” and “stems” 585 Animal Origins 621 Liverwort gametophytes are either thalloid or leafy 587 Molecular systematics helps biologists interpret the fossil record 622 Hornwort gametophytes are inconspicuous thalloid plants 587 Biologists develop hypotheses about the evolution of development 622 Bryophytes are used for experimental studies 588 Details of bryophyte evolution are based on fossils Reconstructing Animal Phylogeny 622 and on structural and molecular evidence 589 Animals exhibit two main types of body symmetry 622 Animal body plans are linked to the level of tissue Seedless Vascular Plants 589 development 624F o c u s O n : Ancient Plants and Coal Formation 590 Biologists group animals according to type of body cavity 624 Club mosses are small plants with rhizomes and short, erect Bilateral animals form two main groups based on differences branches 591 in development 625 Ferns are a diverse group of spore-forming vascular Biologists have identified major animal groups based plants 591 on structure 625 Some ferns and club mosses are heterosporous 595 Molecular data contribute to our understanding Seedless vascular plants are used for experimental studies 595 of animal relationships 626 Seedless vascular plants arose more than 420 mya 595 The Parazoa: Sponges 630 Collar cells characterize sponges 630 The Radiata: Animals with Radial Symmetry and Two Cell Layers 631 28 THE PLANT KINGDOM: Cnidarians have unique stinging cells 631 SEED PLANTS 600 Comb jellies have adhesive glue cells that trap prey 636 An Introduction to Seed Plants 601 Gymnosperms 601 Conifers are woody plants that produce seeds 30 THE ANIMAL KINGDOM: in cones 602 THE PROTOSTOMES 640 Cycads have seed cones and compound leaves 605 Importance of the Coelom 641 Ginkgo biloba is the only living species in its phylum 606 Gnetophytes include three unusual genera 606 The Lophotrochozoa 641 Flatworms are bilateral acoelomates 641 Flowering Plants 607 Phylum Nemertea is characterized by the proboscis 643 Monocots and eudicots are the two largest classes Mollusks have a muscular foot, visceral mass, and mantle 644 of flowering plants 608 Annelids are segmented worms 649 Flowers are involved in sexual reproduction 608 The lophophorate phyla are distinguished by a ciliated ring of The life cycle of flowering plants includes double tentacles 652 fertilization 610 Rotifers have a crown of cilia 653 Seeds and fruits develop after fertilization 611 Flowering plants have many adaptations that account The Ecdysozoa 654 for their success 611 Roundworms are of great ecological importance 654 Studying how flowers evolved provides insights into the Arthropods are characterized by jointed appendages and an evolutionary process 613 exoskeleton of chitin 655 Contents xvii
    • 31 THE ANIMAL KINGDOM: The vascular tissue system consists of two complex THE DEUTEROSTOMES 667 tissues 706 The dermal tissue system consists of two complex tissues 708 What Are Deuterostomes? 668 Plant Meristems 710 Echinoderms 668 Primary growth takes place at apical meristems 711 Members of class Crinoidea are suspension feeders 668 Secondary growth takes place at lateral meristems 712 Many members of class Asteroidea capture prey 669 Class Ophiuroidea is the largest class of echinoderms 670 Members of class Echinoidea have movable spines 670 Members of class Holothuroidea are elongated, sluggish 33 LEAF STRUCTURE AND FUNCTION 715 animals 671 Leaf Form and Structure 716 Chordate Characters 671 Leaf structure consists of an epidermis, photosynthetic ground Invertebrate Chordates 672 tissue, and vascular tissue 716 Tunicates are common marine animals 672 Leaf structure is related to function 720 Lancelets may be closely related to vertebrates 673 F o c u s O n : Air Pollution and Leaves 721 Systematists are making progress in understanding chordate phylogeny 674 Stomatal Opening and Closing 722 Blue light triggers stomatal opening 722 Introducing the Vertebrates 674 Additional factors affect stomatal opening and closing 724 The vertebral column is a key vertebrate character 674 Vertebrate taxonomy is a work in progress 676 Transpiration and Guttation 724 Some plants exude liquid water 725 Jawless Fishes 677 Leaf Abscission 725 Evolution of Jaws and Limbs: Jawed Fishes and Amphibians 678 In many leaves, abscission occurs at an abscission zone near the base of the petiole 726 Members of class Chondrichthyes are cartilaginous fishes 678 The ray-finned fishes gave rise to modern bony fishes 680 Modified Leaves 726 Descendants of the lungfishes moved onto the land 680 Modified leaves of carnivorous plants capture insects 728 Amphibians were the first successful land vertebrates 682 Amniotes 683 Our understanding of amniote phylogeny is changing 684 34 STEMS AND TRANSPORT Reptiles have many terrestrial adaptations 686 IN VASCULAR PLANTS 731 We can assign extant reptiles to four groups 686 External Stem Structure in Woody Twigs 732 Are birds really dinosaurs? 687 Stem Growth and Structure 732 Some dinosaurs had feathers 688 Herbaceous eudicot and monocot stems differ in internal Modern birds are adapted for flight 689 structure 733 Mammals are characterized by hair and mammary glands 690 Woody plants have stems with secondary growth 734 F o c u s O n : Tree-Ring Analysis 738 Transport in the Plant Body 739 Water and minerals are transported in xylem 740 Sugar in solution is translocated in phloem 742 Part 6 STRUCTURE AND LIFE PROCESSES IN PLANTS 698 35 ROOTS AND MINERAL NUTRITION 748 Root Structure and Function 749 32 PLANT STRUCTURE, GROWTH, Roots have root caps and root hairs 749 AND DIFFERENTIATION 698 The arrangement of vascular tissues distinguishes the roots of Plant Structure and Life Span 699 herbaceous eudicots and monocots 749 Plants have different life history strategies 700 Woody plants have roots with secondary growth 753 The Plant Body 700 Some roots are specialized for unusual functions 754 The plant body consists of cells and tissues 700 Root Associations with Fungi and Bacteria 756 The ground tissue system is composed of three simple Mycorrhizae facilitate the uptake of essential minerals by tissues 702 roots 756i xviii Contents www.thomsonedu.com/biology/solomon
    • Rhizobial bacteria fix nitrogen in the roots of leguminous Gibberellins promote stem elongation 794 plants 756 Cytokinins promote cell division 795 The Soil Environment 757 F o c u s O n : Cell and Tissue Culture 796 Soil is composed of inorganic minerals, organic matter, air, Ethylene promotes abscission and fruit ripening 797 and water 758 Abscisic acid promotes seed dormancy 797 The organisms living in the soil form a complex ecosystem 760 Additional signaling molecules affect growth and development, including plant defenses 798 Soil pH affects soil characteristics and plant growth 760 Progress is being made in identifying the elusive flower- Soil provides most of the minerals found in plants 761 promoting signal 799 Soil can be damaged by human mismanagement 762 Light Signals and Plant Development 800 Phytochrome detects day length 801 Competition for sunlight among shade-avoiding plants36 REPRODUCTION IN FLOWERING involves phytochrome 802 PLANTS 767 Phytochrome is involved in other responses to light, including germination 802 The Flowering Plant Life Cycle 768 Phytochrome acts by signal transduction 802 Flowers develop at apical meristems 769 Light influences circadian rhythms 803 Each part of a flower has a specific function 769 Female gametophytes are produced in the ovary, male gametophytes in the anther 769 Pollination 771 Many plants have mechanisms to prevent self-pollination 771 Flowering plants and their animal pollinators have Part 7 STRUCTURE AND LIFE PROCESSES coevolved 771 IN ANIMALS 807 Some flowering plants depend on wind to disperse pollen 774 Fertilization and Seed/Fruit Development 775 38 ANIMAL STRUCTURE AND FUNCTION: A unique double fertilization process occurs in flowering plants 776 AN INTRODUCTION 807 Embryonic development in seeds is orderly and Tissues 808 predictable 776 Epithelial tissues cover the body and line its cavities 808 The mature seed contains an embryonic plant and storage Connective tissues support other body structures 809 materials 777 Muscle tissue is specialized to contract 815 Fruits are mature, ripened ovaries 777 Seed dispersal is highly varied 780 F o c u s O n : Unwelcome Tissues: Cancers 816 Germination and Early Growth 782 Nervous tissue controls muscles and glands 817 Some seeds do not germinate immediately 782 Organs and Organ Systems 817 Eudicots and monocots exhibit characteristic patterns of early The body maintains homeostasis 817 growth 782 Regulating Body Temperature 822 Asexual Reproduction in Flowering Plants 783 Ectotherms absorb heat from their surroundings 823 Apomixis is the production of seeds without the sexual Endotherms derive heat from metabolic processes 823 process 784 Many animals adjust to challenging temperature changes 824 A Comparison of Sexual and Asexual Reproduction 785 Sexual reproduction has some disadvantages 785 39 PROTECTION, SUPPORT, AND MOVEMENT 827 Epithelial Coverings 82837 PLANT GROWTH Invertebrate epithelium may function in secretion AND DEVELOPMENT 789 or gas exchange 828 Tropisms 790 Vertebrate skin functions in protection and temperature Plant Hormones and Development 791 regulation 828 Plant hormones act by signal transduction 791 Skeletal Systems 829 Auxins promote cell elongation 792 In hydrostatic skeletons, body fluids transmit force 829 Contents xix
    • Mollusks and arthropods have nonliving exoskeletons 830 The midbrain is prominent in fishes and amphibians 869 Internal skeletons are capable of growth 830 The forebrain gives rise to the thalamus, hypothalamus, The vertebrate skeleton has two main divisions 831 and cerebrum 869 Muscle Contraction 833 The Human Central Nervous System 871 Invertebrate muscle varies among groups 834 The spinal cord transmits impulses to and from the Insect flight muscles are adapted for rapid contraction 834 brain 871 Vertebrate skeletal muscles act antagonistically The most prominent part of the human brain is the to one another 834 cerebrum 872 A vertebrate muscle may consist of thousands Brain activity cycles in a sleep–wake pattern 873 of muscle fibers 835 The limbic system affects emotional aspects of behavior 876 Contraction occurs when actin and myosin filaments F o c u s O n : The Neurobiology of Traumatic slide past one another 837 Experience 879 ATP powers muscle contraction 840 The strength of muscle contraction varies 840 Information Processing 880 Muscle fibers may be specialized for slow or quick Learning involves the storage of information and its responses 841 retrieval 881 Smooth muscle and cardiac muscle are involuntary 842 Language involves comprehension and expression 883 The Peripheral Nervous System 883 The somatic division helps the body adjust to the external environment 884 40 NEURAL SIGNALING 845 The autonomic division regulates the internal Information Flow through the Nervous environment 884 System 846 Effects of Drugs on the Nervous System 886 Neurons and Glial Cells 847 F o c u s O n : Alcohol: The Most Abused Drug 887 A typical neuron consists of a cell body, dendrites, and an axon 847 Glial cells provide metabolic and structural support 848 Transmitting Information along the Neuron 849 The neuron membrane has a resting potential 849 42 SENSORY SYSTEMS 893 Graded local signals vary in magnitude 851 How Sensory Systems Work 894 An action potential is generated by an influx of Naϩ and an Sensory receptors receive information 894 efflux of Kϩ 851 Sensory receptors transduce energy 894 Neural Signaling across Synapses 855 Sensory input is integrated at many levels 894 Signals across synapses can be electrical or chemical 855 Types of Sensory Receptors 896 Neurons use neurotransmitters to signal other cells 855 Thermoreceptors 897F o c u s O n : Alzheimer’s Disease 857 Electroreceptors and Electromagnetic Neurotransmitters bind with receptors on postsynaptic Receptors 898 cells 859 Nociceptors 898 Activated receptors can send excitatory or inhibitory Mechanoreceptors 898 signals 859 Touch receptors are located in the skin 899 Neural Integration 860 Proprioceptors help coordinate muscle movement 899 Neural Circuits 861 Many invertebrates have gravity receptors called statocysts 900 Hair cells are characterized by stereocilia 901 Lateral line organs supplement vision in fishes 901 41 NEURAL REGULATION 865 The vestibular apparatus maintains equilibrium 901 Invertebrate Nervous Systems 866 Auditory receptors are located in the cochlea 903 Organization of the Vertebrate Nervous Chemoreceptors 906 System 867 Taste receptors detect dissolved food molecules 906 Evolution of the Vertebrate Brain 868 The olfactory epithelium is responsible for the sense The hindbrain develops into the medulla, pons, of smell 908 and cerebellum 868 Many animals communicate with pheromones 909xx Contents www.thomsonedu.com/biology/solomon
    • Photoreceptors 909 Cytokines and complement mediate immune responses 948 Invertebrate photoreceptors include eyespots, simple eyes, Inflammation is a protective response 949 and compound eyes 909 Specific Immune Responses 950 Vertebrate eyes form sharp images 910 Many types of cells are involved in specific immune The retina contains light-sensitive rods and cones 912 responses 950 The major histocompatibility complex is responsible for recognition of self 952 43 INTERNAL TRANSPORT 919 Cell-Mediated Immunity 952 Types of Circulatory Systems 920 Antibody-Mediated Immunity 952 Many invertebrates have an open circulatory system 920 A typical antibody consists of four polypeptide chains 953 Some invertebrates have a closed circulatory system 921 Antibodies are grouped in five classes 954 Vertebrates have a closed circulatory system 922 Antigen–antibody binding activates other defenses 955 Vertebrate Blood 922 The immune system responds to millions of different antigens 956 Plasma is the fluid component of blood 922 Monoclonal antibodies are highly specific 958 Red blood cells transport oxygen 923 White blood cells defend the body against disease Immunological Memory 958 organisms 924 A secondary immune response is more effective than a primary Platelets function in blood clotting 925 response 958 Immunization induces active immunity 959 Vertebrate Blood Vessels 925 Passive immunity is borrowed immunity 960 Evolution of the Vertebrate Cardiovascular System 927 The Immune System and Disease 960 The Human Heart 928 Cancer cells evade the immune system 960 Each heartbeat is initiated by a pacemaker 930 Immunodeficiency disease can be inherited or acquired 961 The nervous system regulates heart rate 932 HIV is the major cause of acquired immunodeficiency in adults 961 Stroke volume depends on venous return 932 Cardiac output varies with the body’s need 932 Harmful Immune Responses 964 Graft rejection is an immune response against transplanted Blood Pressure 933 tissue 964F o c u s O n : Cardiovascular Disease 934 Rh incompatibility can result in hypersensitivity 965 Blood pressure varies in different blood vessels 934 Allergic reactions are directed against ordinary environmental Blood pressure is carefully regulated 935 antigens 965 In an autoimmune disease, the body attacks its own The Pattern of Circulation 937 tissues 966 The pulmonary circulation oxygenates the blood 937 The systemic circulation delivers blood to the tissues 937 The Lymphatic System 938 45 GAS EXCHANGE 970 The lymphatic system consists of lymphatic vessels and lymph Adaptations for Gas Exchange in Air tissue 939 or Water 971 The lymphatic system plays an important role in fluid Types of Respiratory Surfaces 971 homeostasis 940 The body surface may be adapted for gas exchange 971 Tracheal tube systems deliver air directly to the cells 971 Gills are the respiratory surfaces in many aquatic animals 972 44 THE IMMUNE SYSTEM: Terrestrial vertebrates exchange gases through lungs 973 INTERNAL DEFENSE 944 The Mammalian Respiratory System 975 Nonspecific and Specific Immunity: The airway conducts air into the lungs 975 An Overview 945 Gas exchange occurs in the alveoli of the lungs 976 The immune system responds to danger signals 945 Ventilation is accomplished by breathing 976 Invertebrates launch nonspecific immune responses 946 The quantity of respired air can be measured 978 Vertebrates launch nonspecific and specific immune Gas exchange takes place in the alveoli 978 responses 946 Gas exchange takes place in the tissues 979 Nonspecific Immune Responses 946 Respiratory pigments increase capacity for oxygen Phagocytes and natural killer cells destroy pathogens 947 transport 979 Contents xxi
    • Carbon dioxide is transported mainly as bicarbonate ions 980 Osmoregulation and Excretion in Breathing is regulated by respiratory centers in the brain 981 Invertebrates 1013 Hyperventilation reduces carbon dioxide concentration 982 Nephridial organs are specialized for osmoregulation and/or High flying or deep diving can disrupt homeostasis 982 excretion 1013 Some mammals are adapted for diving 982 Malpighian tubules conserve water 1014 Breathing Polluted Air 983 Osmoregulation and Excretion in Vertebrates 1015F o c u s O n : The Effects of Smoking 984 Freshwater vertebrates must rid themselves of excess water 1015 Marine vertebrates must replace lost fluid 1016 46 PROCESSING FOOD Terrestrial vertebrates must conserve water 1016 AND NUTRITION 989 The Urinary System 1017 The nephron is the functional unit of the kidney 1018 Nutritional Styles and Adaptations 990 Urine is produced by filtration, reabsorption, and Animals are adapted to their mode of nutrition 990 secretion 1019 Some invertebrates have a digestive cavity with a single Urine becomes concentrated as it passes through the renal opening 991 tubule 1021 Most animal digestive systems have two openings 992 Urine consists of water, nitrogenous wastes, and salts 1022 The Vertebrate Digestive System 992 Hormones regulate kidney function 1023 Food processing begins in the mouth 993 The pharynx and esophagus conduct food to the stomach 994 Food is mechanically and enzymatically digested in the stomach 994 Most enzymatic digestion takes place in the small 48 ENDOCRINE REGULATION 1028 intestine 995 The liver secretes bile 996 An Overview of Endocrine Regulation 1029 The pancreas secretes digestive enzymes 996 The endocrine system and nervous system interact to regulate the body 1029 Nutrients are digested as they move through the digestive tract 997 Negative feedback systems regulate endocrine activity 1029 Nerves and hormones regulate digestion 998 Hormones are assigned to four chemical groups 1030 Absorption takes place mainly through the villi of the small Types of Endocrine Signaling 1031 intestine 999 Neurohormones are transported in the blood 1031 The large intestine eliminates waste 1000 Some local regulators are considered hormones 1031 Required Nutrients 1000 F o c u s O n : Anabolic Steroids and Other Abused Carbohydrates provide energy 1001 Hormones 1032 Lipids provide energy and are used to make biological molecules 1001 Mechanisms of Hormone Action 1033 Proteins serve as enzymes and as structural components Some hormones enter target cells and activate genes 1033 of cells 1002 Many hormones bind to cell-surface receptors 1033 Vitamins are organic compounds essential for normal Invertebrate Neuroendocrine Systems 1035 metabolism 1002 The Vertebrate Endocrine System 1036 Minerals are inorganic nutrients 1003 Homeostasis depends on normal concentrations Antioxidants protect against oxidants 1003 of hormones 1036 Phytochemicals play important roles in maintaining The hypothalamus regulates the pituitary gland 1037 health 1003 The posterior lobe of the pituitary gland releases hormones Energy Metabolism 1005 produced by the hypothalamus 1038 Undernutrition can cause serious health problems 1006 The anterior lobe of the pituitary gland regulates growth and Obesity is a serious nutritional problem 1006 other endocrine glands 1038 Thyroid hormones increase metabolic rate 1041 The parathyroid glands regulate calcium 47 OSMOREGULATION AND DISPOSAL concentration 1042 The islets of the pancreas regulate glucose OF METABOLIC WASTES 1011 concentration 1043 Maintaining Fluid and Electrolyte Balance 1012 The adrenal glands help the body respond to stress 1045 Metabolic Waste Products 1012 Many other hormones are known 1047xxii Contents www.thomsonedu.com/biology/solomon
    • 49 REPRODUCTION 1051 Sperm and egg pronuclei fuse, restoring the diploid state 1083 Asexual and Sexual Reproduction 1052 Asexual reproduction is an efficient strategy 1052 Cleavage 1083 Most animals reproduce sexually 1052 The pattern of cleavage is affected by yolk 1083 Sexual reproduction increases genetic variability 1053 Cleavage may distribute developmental determinants 1085 Cleavage provides building blocks for development 1086 Human Reproduction: The Male 1054 The testes produce gametes and hormones 1054 Gastrulation 1087 A series of ducts store and transport sperm 1056 The amount of yolk affects the pattern of gastrulation 1087 The accessory glands produce the fluid portion Organogenesis 1089 of semen 1056 Extraembryonic Membranes 1091 The penis transfers sperm to the female 1057 Human Development 1091 Testosterone has multiple effects 1057 The placenta is an organ of exchange 1092 The hypothalamus, pituitary gland, and testes regulate male reproduction 1058 Organ development begins during the first trimester 1094 Development continues during the second and third Human Reproduction: The Female 1058 trimesters 1094 The ovaries produce gametes and sex hormones 1059 More than one mechanism can lead to a multiple birth 1095 The oviducts transport the secondary oocyte 1060 Environmental factors affect the embryo 1095 The uterus incubates the embryo 1061 The neonate must adapt to its new environment 1095 The vagina receives sperm 1061 Aging is not a uniform process 1097 The vulva are external genital structures 1061 Homeostatic response to stress decreases during aging 1097 The breasts function in lactation 1062F o c u s O n : Breast Cancer 1063 The hypothalamus, pituitary gland, and ovaries regulate female reproduction 1063 51 ANIMAL BEHAVIOR 1101 Menstrual cycles stop at menopause 1067 Behavior and Adaptation 1102 Most mammals have estrous cycles 1067 Interaction of Genes and Environment 1102 Sexual Response 1067 Behavior depends on physiological readiness 1103 Fertilization and Early Development 1068 Many behavior patterns depend on motor programs 1104F o c u s O n : Novel Origins 1069 Learning from Experience 1104 An animal habituates to irrelevant stimuli 1105 The Birth Process 1070 Imprinting occurs during an early critical period 1105 Birth Control Methods 1071 In classical conditioning, a reflex becomes associated Most hormone contraceptives prevent ovulation 1073 with a new stimulus 1106 Intrauterine devices are widely used 1073 In operant conditioning, spontaneous behavior is Other common contraceptive methods include the diaphragm reinforced 1106 and condom 1074 Animal cognition is controversial 1107 Emergency contraception is available 1074 Play may be practice behavior 1108 Sterilization renders an individual incapable of producing Biological Rhythms and Migration 1108 offspring 1074 Biological rhythms affect behavior 1108 Abortions can be spontaneous or induced 1075 Migration involves interactions among biological rhythms, Sexually Transmitted Diseases 1075 physiology, and environment 1109 Foraging Behavior 1110 Communication and Living in Groups 1111 Communication is necessary for social behavior 1111 50 ANIMAL DEVELOPMENT 1080 Animals benefit from social organization 1113 Development of Form 1081 Many animals defend a territory 1114 Fertilization 1081 Sexual Selection 1115 The first step in fertilization involves contact and Animals of the same sex compete for mates 1115 recognition 1081 Animals choose quality mates 1115 Sperm entry is regulated 1082 Sexual selection favors polygynous mating systems 1116 Fertilization activates the egg 1083 Some animals care for their young 1117 Contents xxiii
    • Helping Behavior 1118 Natural selection shapes the body forms and behaviors of both Altruistic behavior can be explained by inclusive predator and prey 1153 fitness 1118 F o c u s O n : Batesian Butterflies Disproved 1155 Helping behavior may have alternative explanations 1120 Symbiosis involves a close association between species 1156 Some animals help nonrelatives 1120 Keystone species and dominant species affect the character Highly Organized Societies 1121 of a community 1157 Social insects form elaborate societies 1121 Community Biodiversity 1158 Vertebrate societies tend to be relatively flexible 1122 Ecologists seek to explain why some communities have more Sociobiology explains human social behavior in terms species than others 1158 of adaptation 1123 Species richness may promote community stability 1161 Community Development 1161 Disturbance influences succession and species richness 1162 Ecologists continue to study community structure 1163Part 8 THE INTERACTIONS OF LIFE: ECOLOGY 1126 54 ECOSYSTEMS AND THE BIOSPHERE 1166 Energy Flow through Ecosystems 1167 52 INTRODUCTION TO ECOLOGY: Ecological pyramids illustrate how ecosystems work 1168 POPULATION ECOLOGY 1126 Ecosystems vary in productivity 1169 Features of Populations 1127 Food chains and poisons in the environment 1171 Density and dispersion are important features Cycles of Matter in Ecosystems 1172 of populations 1127 Carbon dioxide is the pivotal molecule in the carbon Changes in Population Size 1129 cycle 1173 Dispersal affects the growth rate in some populations 1129 Bacteria are essential to the nitrogen cycle 1174 Each population has a characteristic intrinsic rate The phosphorus cycle lacks a gaseous component 1176 of increase 1129 Water moves among the ocean, land, and atmosphere No population can increase exponentially indefinitely 1130 in the hydrologic cycle 1177 Factors Influencing Population Size 1131 Ecosystem Regulation from the Bottom Up Density-dependent factors regulate population size 1131 and the Top Down 1178 Density-independent factors are generally abiotic 1133 Abiotic Factors in Ecosystems 1179 Life History Traits 1134 The sun warms Earth 1179 Life tables and survivorship curves indicate mortality F o c u s O n : Life without the Sun 1180 and survival 1136 The atmosphere contains several gases essential Metapopulations 1137 to organisms 1180 Human Populations 1139 The global ocean covers most of Earth’s surface 1182 Not all countries have the same growth rate 1140 Climate profoundly affects organisms 1183 The age structure of a country helps predict future population Fires are a common disturbance in some ecosystems 1184 growth 1141 Studying Ecosystem Processes 1185 Environmental degradation is related to population growth and resource consumption 1142 55 ECOLOGY AND THE GEOGRAPHY OF LIFE 1189 53 COMMUNITY ECOLOGY 1146 Biomes 1190 Community Structure and Functioning 1147 Tundra is the cold, boggy plains of the far north 1190 Community interactions are often complex and not readily Boreal forest is the evergreen forest of the north 1191 apparent 1147 Temperate rain forest has cool weather, dense fog, The niche is a species’ ecological role in the and high precipitation 1192 community 1148 Temperate deciduous forest has a canopy of broad-leaf Competition is intraspecific or interspecific 1149 trees 1194xxiv Contents www.thomsonedu.com/biology/solomon
    • Temperate grasslands occur in areas of moderate Restoring damaged or destroyed habitats is the goal precipitation 1194 of restoration ecology 1221 Ex situ conservation attempts to save species on the brinkF o c u s O n : The Distribution of Vegetation on of extinction 1221 Mountains 1195 The Endangered Species Act provides some legal protection Chaparral is a thicket of evergreen shrubs and small trees 1196 for species and habitats 1222 Deserts are arid ecosystems 1196 International agreements provide some protection of species Savanna is a tropical grassland with scattered trees 1197 and habitats 1223 There are two basic types of tropical forests 1198 Deforestation 1224 Aquatic Ecosystems 1199 Why are tropical rain forests disappearing? 1224 Freshwater ecosystems are closely linked to land and marine Why are boreal forests disappearing? 1225 ecosystems 1200 Global Warming 1226 Estuaries occur where fresh water and salt water meet 1203 Greenhouse gases cause global warming 1226 Marine ecosystems dominate Earth’s surface 1204 What are the probable effects of global warming? 1227 Ecotones 1207 Declining Stratospheric Ozone 1229 Biogeography 1208 Certain chemicals destroy stratospheric ozone 1229 Land areas are divided into six biogeographic realms 1208 Ozone depletion harms organisms 1230 International cooperation is helping repair the ozone layer 1230 56 GLOBAL ENVIRONMENTAL Connections among Environmental Problems 1231 ISSUES 1212 The Biodiversity Crisis 1213 Appendix A Periodic Table of the Elements A-1 Endangered species have certain characteristics in common 1214 Appendix B Classification of Organisms A-2F o c u s O n : Declining Amphibian Populations 1215 Appendix C Understanding Biological Terms A-6 Human activities contribute to declining biological Appendix D Abbreviations A-9 diversity 1215 Appendix E Answers to Test Your Understanding Conservation Biology 1219 Questions A-11 In situ conservation is the best way to preserve biological diversity 1219 Glossary G-1 Landscape ecology considers ecosystem types on a regional Index I-1 scale 1220 Preface Contents xxv
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    • PrefaceThis eighth edition of Solomon, Berg, Martin Biology continues Analyzing Data questions require students to actively interpretto convey our vision of the dynamic science of biology and how experimental data presented in the text.it affects every aspect of our lives, from our health and behavior Throughout the text, we stimulate interest by relating con-to the challenging environmental issues that confront us. Recent cepts to experiences within the student’s frame of reference.discoveries in the biological sciences have increased our under- By helping students make such connections, we facilitate theirstanding of both the unity and diversity of life’s processes and ad- mastery of general concepts. We hope the combined effect of anaptations. With this understanding, we have become more aware engaging writing style and interesting features will fascinate stu-of our interdependence with the vast diversity of organisms with dents and encourage them to continue their study of biology.which we share planet Earth.BIOLOGY IS A BOOK FOR STUDENTS THE SOLOMON/BERG/MARTINThe study of biology can be an exciting journey of discovery for LEARNING SYSTEMbeginning biology students. To that end, we seek to help stu- In the eighth edition we have refined our highly successful Learn-dents better appreciate Earth’s diverse organisms, their remark- ing System, which concentrates on learning objectives and out-able adaptations to the environment, and their evolutionary and comes. Mastering biology is challenging, particularly becauseecological relationships. We also want students to appreciate the the subject of biology is filled with so many facts that must beworkings of science and the contributions of scientists whose integrated into the framework of general biological principles.discoveries not only expand our knowledge of biology but also To help students, we provide Learning Objectives both for thehelp shape and protect the future of our planet. Biology provides course and for each major section of every chapter. At the endinsight into what science is, how scientists work, what the roles of each section, we provide Review questions based on the learn-are of the many scientists who have contributed to our current ing objectives so students can assess their mastery of the materialunderstanding of biology, and how scientific knowledge affects presented in the section.daily life. Throughout the book, students are directed to Thomson- Since the first edition of Biology, we have tried to present the NOW, a powerful online diagnostic tool that helps students assessprinciples of biology in an integrated way that is accurate, in- their study needs and master the chapter objectives. After takingteresting, and conceptually accessible to students. In this eighth a pretest on ThomsonNOW, students receive feedback based onedition of Biology, we continue this tradition. We also continue their answers as well as a Personalized Study plan with links toto present biology in an inquiry-based framework. Many pro- animations and other resources keyed to their specific learningfessors interpret inquiry as a learning method that takes place needs. Selected illustrations in the text are also keyed to Animatedin the laboratory as students perform experiments. Laboratory figures in ThomsonNOW.research is certainly an integral part of inquiry-based learning.But inquiry is also a way of learning in which the student activelypursues some line of knowledge outside the laboratory. In Biol-ogy, we have always presented the history of scientific advances, Course Learning Objectivesincluding scientific debates, to help students understand that At the end of a successful study of introductory biology, the stu-science is a process (that is, a field of investigative inquiry) as dent can demonstrate mastery of the subject by responding accu-well as a body of knowledge (the product of inquiry). NEW In rately to the following Course Learning Objectives, or Outcomes:Biology, Eighth Edition, we make a concerted effort to furtherintegrate inquiry-based learning into the textbook with the inclu- • Design an experiment to test a given hypothesis, using thesion of two new features: Key Experiment figures and Analyzing procedure and terminology of the scientific method.Data questions. Key Experiment figures encourage students to • Cite the cell theory, and relate structure to function in bothevaluate investigative approaches that real scientists have taken. prokaryotic and eukaryotic cells. xxvii
    • • Describe the theory of evolution, explain why it is the princi- • Numerous Tables, many illustrated, help the student orga- pal unifying concept in biology, and discuss natural selection nize and summarize material presented in the text. as the primary agent of evolutionary change. • A Summary with Key Terms at the end of each chapter is • Explain the role of genetic information in all species, and organized around the chapter Learning Objectives. This discuss applications of genetics that affect society. summary provides a review of the material, and because • Describe several mechanisms by which cells and organisms selected key terms are boldface in the summary, students are transfer information, including the use of nucleic acids, provided the opportunity to study vocabulary words within chemical signals (such as hormones and pheromones), the context of related concepts. electrical signals (for example, neural transmission), signal • End-of-chapter questions provide students with the op- transduction, sounds, and visual displays. portunity to evaluate their understanding of the material in • Argue for or against the classification of organisms in three the chapter. Test Your Understanding consists of multiple- domains and six kingdoms, characterizing each of these choice questions, some of which are based on the recall clades; based on your knowledge of genetics and evolution, of important terms, whereas others challenge students to give specific examples of the unity and diversity of these integrate their knowledge. Answers to the Test Your Under- organisms. standing questions are provided in Appendix E. A series of thought-provoking Critical Thinking questions encourages • Compare the structural adaptations, life processes, and life the student to apply the concepts just learned to new situ- cycles of a prokaryote, protist, fungus, plant, and animal. ations or to make connections among important concepts. • Define homeostasis, and give examples of regulatory mecha- NEW Every chapter has one or more Evolution Link ques- nisms, including feedback systems. tions in the Critical Thinking section. NEW Many chapters • Trace the flow of matter and energy through a photosyn- contain one or more Analyzing Data questions based on thetic cell and a nonphotosynthetic cell, and through the data presented in the chapter. biosphere, comparing the roles of producers, consumers, • The Glossary at the end of the book, the most comprehen- and decomposers. sive glossary found in any biology text, provides precise defi- • Describe the study of ecology at the levels of an individual nitions of terms. The Glossary is especially useful because it organism, a population, a community, and an ecosystem. is extensively cross-referenced and includes pronunciations. The vertical blue bar along the margin facilitates rapid access Pedagogical Features to the Glossary. The companion website also includes glos- sary flash cards with audio pronunciations. We use numerous learning strategies to increase the student’s • NEW An updated and expanded art program brings to life, success: reinforces, and expands concepts discussed in the text. This • NEW A list of Key Concepts at the beginning of each chapter edition includes Key Experiment figures, which emphasize provides a chapter overview. the scientific process in both classic and modern research; • Learning Objectives at the beginning of each major section examples include Figures 9-7, 17-2, 36-7, and 50-8. Also in the chapter indicate, in behavioral terms, what the student new to this edition are Key Points stated in process diagrams must do to demonstrate mastery of the material in that of complex topics; examples include Figures 28-19 and section. 54-2. Many of these figures have numbered parts that show • Each major section of the chapter is followed by a series of sequences of events in biological processes or life cycles. Review questions that assess comprehension by asking the Numerous photographs, both alone and combined with line student to describe, explain, compare, contrast, or illustrate art, help students grasp concepts by connecting the “real” important concepts. The Review questions are based on the to the “ideal.” The line art uses devices such as orienta- section Learning Objectives. tion icons to help the student put the detailed figures into the broad context. We use symbols and colors consistently • Concept Statement Subheads introduce sections, preview- throughout the book to help students connect concepts. For ing and summarizing the key idea or ideas to be discussed in example, the same four colors and shapes are used through- that section. out the book to identify guanine, cytosine, adenine, and • Sequence Summaries within the text simplify and summa- thymine. rize information presented in paragraph form. For example, paragraphs describing blood circulation through the body or the steps by which cells take in certain materials are followed by a Sequence Summary listing the structures or steps. • Focus On boxes explore issues of special relevance to stu- WHAT’S NEW: AN OVERVIEW dents, such as the effects of smoking or alcohol abuse. These OF BIOLOGY, EIGHTH EDITION boxes also provide a forum for discussing certain topics of current interest in more detail, such as the smallest ancient Three themes are interwoven throughout Biology: the evolution humans (Homo floresiensis), worldwide declining amphibian of life, the transmission of biological information, and the flow populations, and Alzheimer’s disease. of energy through living systems. As we introduce the conceptsi xxviii Preface www.thomsonedu.com/biology/solomon
    • of modern biology, we explain how these themes are connected ers Mendelian genetics and related patterns of inheritance, has aand how life depends on them. new section on recognition of Mendel’s work, including discus- Educators present the major topics of an introductory biol- sion of the chromosome theory of inheritance. We then turn ourogy course in a variety of orders. For this reason, we carefully attention to the structure and replication of DNA in Chapter 12,designed the eight parts of this book so that they do not depend including a new section on proofreading and repair of errors inheavily on preceding chapters and parts. This flexible organiza- DNA. Chapter 13 has a discussion of RNA and protein synthe-tion means that an instructor can present the 56 chapters in any sis, including a new section and summary table on the differentnumber of sequences with pedagogical success. Chapter 1, which kinds of eukaryotic RNA. Gene regulation is discussed in Chap-introduces the student to the major principles of biology, pro- ter 14, which includes new paragraphs on genomic imprintingvides a good springboard for future discussions, whether the pro- and epigenetic inheritance. In Chapter 15, we focus on DNA tech-fessor prefers a “top-down” or “bottom-up” approach. nology and genomics, including new material on DNA analysis, In this edition, as in previous editions, we examined every genomics, expressed sequence tags, RNAi, and the importanceline of every chapter for accuracy and currency, and we made a of GM crops to U.S. agriculture. These chapters build the neces-serious attempt to update every topic and verify all new mate- sary foundation for exploring the human genome in Chapter 16,rial. The following brief survey provides a general overview of which has expanded discussion of abnormalities in chromosomethe organization of Biology and some changes made to the eighth structure and on X-linked genes affecting intelligence. In Chap-edition. ter 17, we introduce the role of genes in development, emphasiz- ing studies on specific model organisms that have led to spectacu- lar advances in this field; changes include new material on RNAiPart 1: The Organization of Life as a powerful tool in developmental genetics and discussion of cancer as a stem cell disease.The six chapters that make up Part 1 provide basic background NEW The art program in the genetics section includes manyknowledge. We begin Chapter 1 with a new discussion of re- new pieces, such as Figures 10-8 (cohesins), 10-11 (binary fis-search on heart repair and then introduce the main themes of sion), 12-14 (DNA repair), 13-11 (linkage of amino acid to itsthe book— evolution, energy transfer, and information transfer. specific RNA), 13-18 (photo of plants with altered miRNA),Chapter 1 then examines several fundamental concepts in biology 14-1 (lean pig with IGF2 mutation), 14-13 (protein degradationand the nature of the scientific process, including a discussion of by ubiquitin-proteasomes), 15-9 (Southern blotting technique),systems biology. Chapters 2 and 3, which focus on the molecu- 15-15 (DNA fingerprinting), 16-5 (common abnormalities inlar level of organization, establish the foundations in chemistry chromosome structure), 16-10 (gene therapy in mouse bonenecessary for understanding biological processes. Chapters 4 and marrow cells), and 17-6 (six model organisms).5 focus on the cell level of organization. Chapter 4 contains addi-tional information on microtubules, microfilaments, and motorproteins; Chapter 5 has expanded coverage of transport proteins Part 4: The Continuity of Life: Evolutionand a new section on uniporters, symporters, and antiporters. NEW In the eighth edition we have added a new chapter, Although we explore evolution as the cornerstone of biologyChapter 6, on cell communication, because recent studies of cell throughout the book, Part 4 delves into the subject in depth. Wesignaling, including receptor function and signal transduction, provide the history behind the discovery of the theory of evolu-are providing new understanding of many life processes, particu- tion, the mechanisms by which it occurs, and the methods bylarly at the cell level. which it is studied and tested. Chapter 18 introduces the Darwin- ian concept of evolution and presents several kinds of evidence that support the theory of evolution. In Chapter 19, we examinePart 2: Energy Transfer through Living Systems evolution at the population level. Chapter 20 describes the evo- lution of new species and discusses aspects of macroevolution.Because all living cells need energy for life processes, the flow Chapter 21 summarizes the evolutionary history of life on Earth.of energy through living systems — that is, capturing energy and In Chapter 22, we recount the evolution of the primates, includ-converting it to usable forms — is a basic theme of Biology. Chap- ing humans. Many topics and examples have been added to theter 7 examines how cells capture, transfer, store, and use energy. eighth edition, such as new material on developmental biology asChapters 8 and 9 discuss the metabolic adaptations by which or- evidence for evolution in Galápagos finches, the founder effectganisms obtain and use energy through cellular respiration and and genetic drift with respect to Finns and Icelanders, ways ofphotosynthesis. New to Chapter 9 is a summary section on the defining a species, the Archaeon and Proterozoic eons, and a newimportance of photosynthesis to plants and other organisms. Focus On box on Homo floresiensis.Part 3: The Continuity of Life: Genetics Part 5: The Diversity of LifeWe have updated and expanded the eight chapters of Part 3 for In this edition of Biology, we continue to emphasize the cla-the eighth edition. We begin this unit by discussing mitosis and distic approach. We use an evolutionary framework to discussmeiosis in Chapter 10, which includes new sections on binary each group of organisms, presenting current hypotheses of howfission and prometaphase in mitosis. Chapter 11, which consid- groups of organisms are related. Chapter 23 discusses why organ- Preface xxix
    • isms are classified and provides insight into the scientific process behavioral adaptations in Chapter 51. Reflecting recent researchof deciding how they are classified. New advances have enabled findings, we have added new material on homeostasis and theus to further clarify the connection between evolutionary history process of contraction in whole muscle. We have also updatedand systematics in the eighth edition. Chapter 24, which focuses and added new material on neurotransmitters, information pro-on the viruses and prokaryotes, contains a major revision of pro- cessing, thermoreceptors, electroreceptors and magnetorecep-karyote classification and new sections on evolution in bacteria tion, endocrine regulation of blood pressure, Toll-like receptors,and on biofilms. Chapter 25 reflects the developing consensus cytokines, cancer treatment, HIV and autoimmune diseases, newon protist diversity and summarizes evolutionary relationships nutrition guidelines, obesity, maintenance of fluid and electrolyteamong the eight major eukaryote groups. Chapter 26 describes balance, steroid action that allows rapid signaling, melanocyte-the fungi and includes an updated phylogeny with a discussion stimulating hormones (MSH), diabetes, anabolic steroids, meno-of members of phylum Glomeromycota and their role as my- pause, the estrous cycle, contraception, and STDs. In Chapter 51,corrhizal fungi. Chapters 27 and 28 present the members of the we have added new information on cognition, communication,plant kingdom; Chapter 28 includes new material that updates interspecific and intraspecific selection, parental care, and help-the evolution of the angiosperms. In Chapters 29 through 31, ing behavior.which cover the diversity of animals, we place more emphasison molecular systematics. We have also added new sections onanimal origins and the evolution of development. Part 8: The Interactions of Life: Ecology Part 8 focuses on the dynamics of populations, communities, and ecosystems and on the application of ecological principles to disciplines such as conservation biology. Chapters 52 throughPart 6: Structure and Life Processes in Plants 55 give the student an understanding of the ecology of popu-Part 6 introduces students to the fascinating plant world. It lations, communities, ecosystems, and the biosphere, whereasstresses relationships between structure and function in plant Chapter 56 focuses on global environmental issues. Among thecells, tissues, organs, and individual organisms. In Chapter 32, many changes in this unit are new material on secondary pro-we introduce plant structure, growth, and differentiation. Chap- ductivity, top-down and bottom-up processes, characteristics ofters 33 through 35 discuss the structural and physiological adap- endangered species, deforestation, and a greatly expanded sectiontations of leaves, stems, and roots. Chapter 36 describes reproduc- on conservation biology.tion in flowering plants, including asexual reproduction, flowers,fruits, and seeds. Chapter 37 focuses on growth responses andregulation of growth. In the eighth edition, we present the lat-est findings generated by the continuing explosion of knowledge A COMPREHENSIVE PACKAGEin plant biology, particularly at the molecular level. New topics FOR LEARNING AND TEACHINGinclude the molecular basis of mycorrhizal and rhizobial sym-bioses, molecular aspects of floral initiation at apical meristems, A carefully designed supplement package is available to furtherself-incompatibility, and the way that auxin acts by signal trans- facilitate learning. In addition to the usual print resources, weduction. Chapter 36 also discusses a new experiment figure on are pleased to present student multimedia tools that have beenthe evolutionary implications of a single mutation in a gene for developed in conjunction with the text.flower color that resulted in a shift in animal pollinators. Resources for Students Study Guide to Accompany Biology, Eighth Edition, by Ron-Part 7: Structure and Life Processes in Animals ald S. Daniel of California State Polytechnic University, Pomona;In Part 7, we provide a strong emphasis on comparative animal Sharon C. Daniel of Orange Coast College; and Ronald L. Taylor.physiology, showing the structural, functional, and behavioral Extensively updated for this edition, the study guide providesadaptations that help animals meet environmental challenges. the student with many opportunities to review chapter con-We use a comparative approach to examine how various ani- cepts. Multiple-choice study questions, coloring-book exercises,mal groups have solved similar and diverse problems. In Chap- vocabulary-building exercises, and many other types of active-ter 38, we discuss the basic tissues and organ systems of the ani- learning tools are provided to suit different cognitive learningmal body, homeostasis, and the ways that animals regulate their styles.body temperature. Chapter 39 focuses on body coverings, skel-etons, and muscles. In Chapters 40 through 42, we discuss neural A Problem-Based Guide to Basic Genetics by Donald Cronkitesignaling, neural regulation, and sensory reception. In Chap- of Hope College. This brief guide provides students with a sys-ters 43 through 50, we compare how different animal groups carry tematic approach to solving genetics problems, along with nu-on specific life processes, such as internal transport, internal de- merous solved problems and practice problems.fense, gas exchange, digestion, reproduction, and development.Each chapter in this part considers the human adaptations for Spanish Glossary. NEW This Spanish glossary of biology termsthe life processes being discussed. Part 7 ends with a discussion of is available to Spanish-speaking students.xxx Preface www.thomsonedu.com/biology/solomon
    • Website. The content-rich companion website that accompanies We appreciate the hard work of our dedicated Developmen-Biology, Eighth Edition, gives students access to high-quality re- tal Editor, Suzannah Alexander, who provided us with valuablesources, including focused quizzing, a Glossary complete with input as she guided the eighth edition through its many phases.pronunciations, InfoTrac® College Edition readings and exercises, We especially thank Suzannah for sharing her artistic talent andInternet activities, and annotated web links. For these and other for her great ideas for visual presentations. We appreciate the helpresources, visit www.thomsonedu.com /biology/solomon. of Senior Content Project Manager Cheryll Linthicum, Content Project Manager Jennifer Risden, and Project Editor Jamie Arm-ThomsonNOW. NEW This updated and expanded online learn- strong, who expertly shepherded the project. We thank Editorialing tool helps assess students’ personal study needs and focus Assistants Kristin Marrs and Kate Franco for quickly providing ustheir time. By taking a pretest, they are provided with a Personal- with resources whenever we needed them. We appreciate the ef-ized Study plan that directs them to text sections and narrated forts of photo editor Don Murie. We thank Creative Director Robanimations — many of which are new to this edition — that they Hugel, Art Director Lee Friedman, Text Designer John Walker,need to review. If they need to brush up on basic skills, the How and Cover Designer Robin Terra. We also thank Joy Westberg forDo I Prepare? feature walks them through tutorials on basic developing the Instructor’s Preface.math, chemistry, study skills, and word roots. We are grateful to Keli Amann, Technology Project Manager, who coordinated the many high-tech components of the comput-Audio. NEW This edition of Biology is accompanied by a range of erized aspects of our Learning System. We thank Lauren Oliveira,“mobile content” resources, including downloadable study skill Assistant Editor, for coordinating the print supplements. Thesetips and concept reviews in MP3 format for use on a portable dedicated professionals and many others at Brooks /Cole pro-MP3 player. vided the skill, attention, and good humor needed to produce Biology, Eighth Edition. We thank them for their help and sup-Virtual Biology Laboratory 3.0 by Beneski and Waber. NEW port throughout this project.These 14 online laboratory experiments, designed within a simu- A Biology Advisory Board greatly enhanced our preparationlation format, allow students to “do” science by acquiring data, of the eighth edition of Biology. We thank these professionals forperforming experiments, and using data to explain biological their insight and suggestions:concepts. Assigned activities automatically flow to the instruc-tor’s grade book. New self-designed activities ask students to plan Susan R. Barnum, Miami University, Oxford, OH, Moleculartheir procedures around an experimental question and write up biology of cyanobacteriatheir results. Virginia McDonough, Hope College, Molecular biology of lipid metabolism David K. Bruck, San Jose State University, Plant cell biologyAdditional Resources for Instructors Lee F. Johnson, The Ohio State University, Molecular genetics, biochemistryThe instructors’ Examination Copy for this edition lists a com-prehensive package of print and multimedia supplements, in- Karen A. Curto, University of Pittsburgh, Cell signalingcluding online resources, available to qualified adopters. Please Robert J. Kosinski, Clemson University, Introductory biologyask your local sales representative for details. laboratory development Tim Schuh, St. Cloud State University, Developmental biology Robert W. Yost, Indiana University –Purdue University India- napolis, Physiology, animal form and functionACKNOWLEDGMENTS We are grateful to Bruce Mohn of Rutgers University for hisThe development and production of the eighth edition of Biology expert advice on dinosaur and bird evolution and to Bill Norrisrequired extensive interaction and cooperation among the au- of Western New Mexico University for his help with the book’sthors and many individuals in our family, social, and professional cladograms. We thank Dr. Susan Pross, University of South Flor-environments. We thank our editors, colleagues, students, fam- ida, College of Medicine, for her helpful suggestions for updatingily, and friends for their help and support. Preparing a book of the immunology chapter. We greatly appreciate the expert assis-this complexity is challenging and requires a cohesive, talented, tance of Mary Kay Hartung of Florida Gulf Coast University, whoand hardworking professional team. We appreciate the contribu- came to our rescue whenever we had difficulty finding needed re-tions of everyone on the editorial and production staff at Brooks / search studies from the Internet. We thank doctoral student LoisCole / Thomson Learning who worked on this eighth edition of Ball of the University of South Florida, Department of Biology,Biology. We thank Michelle Julet, Vice President and Editor-in- who reviewed several chapters and offered helpful suggestions.Chief, and Peter Adams, Executive Editor, for their commitment We thank obstetrician, gynecologist Dr. Amy Solomon for herto this book and for their support in making the eighth edition input regarding pregnancy, childbirth, conception, and sexuallyhappen. We appreciate Stacy Best and Kara Kindstrom, our Mar- transmitted diseases.keting Managers, whose expertise ensured that you would know We thank our families and friends for their understanding,about our new edition. support, and encouragement as we struggled through many re- Preface xxxi
    • visions and deadlines. We especially thank Mical Solomon, Dr. John Geiser, Western Michigan University Amy Solomon, Dr. Kathleen M. Heide, Alan Berg, Jennifer Berg, William J. Higgins, University of Maryland Dr. Charles Martin, and Margaret Martin for their support and Jeffrey P. Hill, Idaho State University input. We greatly appreciate the many hours Alan Berg devoted to preparing the manuscript. Walter S. Judd, University of Florida Our colleagues and students who have used our book have Mary Jane Keleher, Salt Lake Community College provided valuable input by sharing their responses to past edi- Scott L. Kight, Montclair State University tions of Biology. We thank them and ask again for their comments Joanne Kivela Tillotson, Purchase College SUNY and suggestions as they use this new edition. We can be reached through the Internet at our website www.thomsonedu.com / Will Kleinelp, Middlesex County College biology/solomon or through our editors at Brooks /Cole, a divi- Kenneth M. Klemow, Wilkes University sion of Thomson Learning. Jonathan Lyon, Merrimack College We express our thanks to the many biologists who have read Blasé Maffia, University of Miami the manuscript during various stages of its development and pro- vided us with valuable suggestions for improving it. Eighth edi- Kathleen R. Malueg, University of Colorado, Colorado Springs tion reviewers include the following: Patricia Matthews, Grand Valley State University Joseph J. Arruda, Pittsburg State University David Morgan, Western Washington University Amir M. Assadi-Rad, San Joaquin Delta College Darrel L. Murray, University of Illinois at Chicago Douglas J. Birks, Wilmington College William R. Norris, Western New Mexico University William L. Bischoff, University of Toledo James G. Patton, Vanderbilt University Catherine S. Black, Idaho State University Mitch Price, Penn State Andrew R. Blaustein, Oregon State University Susan Pross, University of South Florida Scott Bowling, Auburn University Jerry Purcell, San Antonio College W. Randy Brooks, Florida Atlantic University Kenneth R. Robinson, Purdue University Mark Browning, Purdue University Darrin Rubino, Hanover College Arthur L. Buikema Jr., Virginia Tech Julie C. Rutherford, Concordia College Anne Bullerjahn, Owens Community College Andrew M. Scala, Dutchess Community College Carolyn J. W. Bunde, Idaho State University Pramila Sen, Houston Community College Scott Burt, Truman State University Mark A. Sheridan, North Dakota State University David Byres, Florida Community College –Jacksonville Marcia Shofner, University of Maryland Jeff Carmichael, University of North Dakota Phillip Snider, Gadsden State Community College Domenic Castignetti, Loyola University of Chicago David Stanton, Saginaw Valley State University Geoffrey A. Church, Fairfield University William Terzaghi, Wilkes University Barbara Collins, California Lutheran University Keti Venovski, Lake Sumter Community College Linda W. Crow, Montgomery College Steven D. Wilt, Bellarmine University Karen J. Dalton, Community College of Baltimore County James R. Yount, Brevard Community College Mark Decker, University of Minnesota We would also like to thank the hundreds of previous edition Jonathan J. Dennis, University of Alberta reviewers, both professors and students, who are too numerous to mention. Without their contributions, Biology, Eighth Edition, Philippa M. Drennan, Loyola Marymount University would not have been the same. They asked thoughtful questions, David W. Eldridge, Baylor University provided new perspectives, offered alternative wordings to clar- H. W. Elmore, Marshall University ify difficult passages, and informed us of possible errors. We are Cheryld L. Emmons, Alfred University truly indebted to their excellent feedback. Robert C. Evans, Rutgers University, Camdeni xxxii Preface www.thomsonedu.com/biology/solomon
    • To the StudentBiology is a challenging subject. The thousands of students we fessor’s requirements are, because the way you study will varyhave taught have differed in their life goals and learning styles. accordingly.Some have had excellent backgrounds in science; others, poorones. Regardless of their backgrounds, it is common for students How to study when professors test lecture materialtaking their first college biology course to find that they mustwork harder than they expected. You can make the task easier by If lectures are the main source of examination questions, makeusing approaches to learning that have been successful for a broad your lecture notes as complete and organized as possible. Beforerange of our students over the years. Be sure to use the Learning going to class, skim over the chapter, identifying key terms andSystem we use in this book. It is described in the Preface. examining the main figures, so that you can take effective lecture notes. Spend no more than 1 hour on this. Within 24 hours after class, rewrite (or type) your notes. Be- fore rewriting, however, read the notes and make marginal notesMake a Study Schedule about anything that is not clear. Then read the correspondingMany college professors suggest that students study 3 hours for material in your text. Highlight or underline any sections thatevery hour spent in class. This major investment in study time is clarify questions you had in your notes. Read the entire chapter,one of the main differences between high school and college. To including parts that are not covered in lecture. This extra infor-succeed academically, college students must learn to manage their mation will give you breadth of understanding and will help youtime effectively. The actual number of hours you spend studying grasp key concepts.biology will vary depending on how quickly you learn the mate- After reading the text, you are ready to rewrite your notes,rial, as well as on your course load and personal responsibilities, incorporating relevant material from the text. It also helps to usesuch as work schedules and family commitments. the Glossary to find definitions for unfamiliar terms. Many stu- The most successful students are often those who are best dents develop a set of flash cards of key terms and concepts as aorganized. At the beginning of the semester, make a detailed daily way to study. Flash cards are a useful tool to help you learn sci-calendar. Mark off the hours you are in each class, along with entific terminology. They are portable and can be used at timestravel time to and from class if you are a commuter. After you get when other studying is not possible, for example, when ridingyour course syllabi, add to your calendar the dates of all exams, a bus.quizzes, papers, and reports. As a reminder, it also helps to add Flash cards are not effective when the student tries to second-an entry for each major exam or assignment 1 week before the guess the professor. (“She won’t ask this, so I won’t make a flashtest or due date. Now add your work schedule and other personal card of it.”) Flash cards are also a hindrance when students relycommitments to your calendar. Using a calendar helps you find on them exclusively. Studying flash cards instead of reading theconvenient study times. text is a bit like reading the first page of each chapter in a mystery Many of our successful biology students set aside 2 hours a novel: It’s hard to fill in the missing parts, because you are learn-day to study biology rather than depend on a weekly marathon ing the facts in a disconnected way.session for 8 or 10 hours during the weekend (when that kindof session rarely happens). Put your study hours into your daily How to study when professorscalendar, and stick to your schedule. test material in the book If the assigned readings in the text are going to be tested, you mustDetermine Whether the Professor Emphasizes use your text intensively. After reading the chapter introduction, read the list of Learning Objectives for the first section. TheseText Material or Lecture Notes objectives are written in behavioral terms; that is, they ask you toSome professors test almost exclusively on material covered in “do” something in order to demonstrate mastery. The objectiveslecture. Others rely on their students’ learning most, or even give you a concrete set of goals for each section of the chapter. Atall, of the content in assigned chapters. Find out what your pro- the end of each section, you will find Review questions keyed to xxxiii
    • the Learning Objectives. Test yourself, going back over the mate- tion of a term, use the Index and Glossary. The more you userial to check your responses. biological terms in speech and writing, the more comfortable you Read each chapter section actively. Many students read and will be.study passively. An active learner always has questions in mindand is constantly making connections. For example, there aremany processes that must be understood in biology. Don’t try to Form a Study Groupblindly memorize these; instead, think about causes and effectsso that every process becomes a story. Eventually, you’ll see that Active learning is facilitated if you do some of your studying in amany processes are connected by common elements. small group. In a study group, the roles of teacher and learner can You will probably have to read each chapter two or three be interchanged: a good way to learn material is to teach. A studytimes before mastering the material. The second and third times group lets you meet challenges in a nonthreatening environmentthrough will be much easier than the first, because you’ll be rein- and can provide some emotional support. Study groups are effec-forcing concepts that you have already partially learned. tive learning tools when combined with individual study of text After reading the chapter, write a four- to six-page chapter and lecture notes. If, however, you and other members of youroutline by using the subheads as the body of the outline (first- study group have not prepared for your meetings by studying in-level heads are boldface, in color, and all caps; second-level heads dividually in advance, the study session can be a waste of time.are in color and not all caps). Flesh out your outline by addingimportant concepts and boldface terms with definitions. Use thisoutline when preparing for the exam. Prepare for the Exam Now it is time to test yourself. Answer the Test Your Under-standing questions, and check your answers. Write answers to Your calendar tells you it is now 1 week before your first biologyeach of the Critical Thinking questions. Finally, review the Learn- exam. If you have been following these suggestions, you are welling Objectives in the Chapter Summary, and try to answer them prepared and will need only some last-minute reviewing. No all-before reading the summary provided. If your professor has told nighters will be required.you that some or all of the exam will be short-answer or essay During the week prior to the exam, spend 2 hours each dayformat, write out the answer for each Learning Objective. Re- actively studying your lecture notes or chapter outlines. It helpsmember that this is a self-test. If you do not know an answer to a many students to read these notes out loud (most people listenquestion, find it in the text. If you can’t find the answer, use the to what they say!). Begin with the first lecture /chapter covered onIndex. the exam, and continue in the order on the lecture syllabus. Stop when you have reached the end of your 2-hour study period. The following day, begin where you stopped the previous day. When you reach the end of your notes, start at the beginning and studyLearn the Vocabulary them a second time. The material should be very familiar to youOne stumbling block for many students is learning the many by the second or third time around. At this stage, use your text-terms that make up the language of biology. In fact, it would book only to answer questions or clarify important points.be much more difficult to learn and communicate if we did not The night before the exam, do a little light studying, eat a nu-have this terminology, because words are really tools for thinking. tritious dinner, and get a full night’s sleep. That way, you’ll arriveLearning terminology generally becomes easier if you realize that in class on exam day with a well-rested body (and brain) and themost biological terms are modular. They consist of mostly Latin self-confidence that goes with being well prepared.and Greek roots; once you learn many of these, you will have a Eldra P. Solomongood idea of the meaning of a new word even before it is defined. Linda R. BergFor this reason, we have included an Appendix on Understanding Diana W. MartinBiological Terms. To be sure you understand the precise defini-xxxiv To the Student www.thomsonedu.com/biology/solomon
    • 1 A View of Life A cardiac muscle cell dividing into two new cells.Felix B. Engel /Children’s Hospital Boston K EY C ONCE P TS H eart disease is the leading cause of death in the United States and other developed countries. When cardiac muscle is dam- aged, for example, by a myocardial infarction (a “heart attack”), Basic themes of biology include evolution, information transfer, and energy for life. the injured muscle does not repair itself. Instead, the muscle is re- Characteristics of life include growth and development, placed by scar tissue that impairs the heart’s ability to pump blood. self-regulated metabolism, response to stimuli, and Researcher Mark T. Keating and his team at the Howard Hughes reproduction. Medical Institute at Children’s Hospital Boston discovered that the Biological organization is hierarchical and includes chemi- small, tropical zebrafish can regenerate up to 20% of its heart mus- cal, cell, tissue, organ, organ system, and organism levels; cle within two months after the tissue is injured or removed. The ecological organization includes population, community, ecosystem, and biosphere levels. challenge is to find the mechanisms that stimulate regeneration and learn how to manipulate them. The tree of life includes three major branches, or domains. Felix Engel, an investigator working with Keating, identified Species evolve by natural selection, adapting to changes in their environment. that a growth factor (known as fibroblast growth factor) can stimu- late cardiac muscle cells to replicate their DNA. The research team Biologists ask questions, develop hypotheses, make predictions, and collect data by careful observation and also discovered that the protein known as p38 inhibits cardiac experiment. muscle growth in fetal rats. They wondered how they could inhibit the inhibitor so that cardiac muscle could repair itself. In 2005, these investigators reported that when they treated cardiac muscle cells with the growth factor in combination with a compound that inhibits p38, cardiac muscle cells activate a group of genes in- volved in cell division and finally divide (see photograph). A research group in Germany is pioneering another approach to treating heart damage. This group, led by Gustav Steinhoff at the University of Rostock, injected stem cells (collected from the 1
    • patient’s own bone marrow) into the cardiac muscle of patients lescence. (At the time of this ruling, 20 states still permitted capitalwho had heart damage as a result of myocardial infarction. One punishment for offenders younger than age 18.) Adolescents haveyear after receiving the injected stem cells, patients who had this not reached neurophysiological maturity and cannot be held ac-treatment in addition to bypass surgery showed significantly bet- countable for their crimes to the same extent as adults.ter heart function compared with patients who had only surgery. Whatever your college major or career goals, knowledge ofSearching for ways to repair damaged hearts is one example of the biological concepts is a vital tool for understanding this worldthousands of new research studies in progress. and for meeting many of the personal, societal, and global chal- This is an exciting time to begin studying biology, the science lenges that confront us. Among these challenges are decreasingof life. The remarkable new discoveries biologists are making al- biological diversity, diminishing natural resources, the expandingmost daily affect every aspect of our lives, including our health, human population, and prevention and cure of diseases, such asfood, safety, relationships with humans and other organisms, and cancer, Alzheimer’s disease, malaria, acquired immunodeficiencyour ability to enjoy the life that surrounds us. New knowledge pro- syndrome (AIDS), and avian flu. Meeting these challenges will re-vides new insights into the human species and the millions of other quire the combined efforts of biologists and other scientists, politi-organisms with which we share this planet. cians, and biologically informed citizens. Biology affects our personal, governmental, and societal deci- This book is a starting point for an exploration of biology. Itsions. For example, the U.S. Supreme Court abolished the death provides you with the basic knowledge and the tools to becomepenalty for juvenile offenders in 2005, based on research findings a part of this fascinating science and a more informed member ofthat the brain does not complete its development until after ado- society. ■ THREE BASIC THEMESLearning Objective ❚ What does the term evolution mean as applied to popula-1 Describe three basic themes of biology. tions of organisms?In this first chapter we introduce three basic themes of biology:1. Evolution. Populations of organisms have evolved through CHARACTERISTICS OF LIFE time from earlier forms of life. Scientists have accumulated Learning Objective a wealth of evidence showing that the diverse life-forms on this planet are related and that populations have evolved, that 2 Distinguish between living and nonliving things by describing the features that characterize living organisms. is, have changed over time, from earlier forms of life. The process of evolution is the framework for the science of biol- We easily recognize that a pine tree, a butterfly, and a horse are ogy and is a major theme of this book. living things, whereas a rock is not. Despite their diversity, the or-2. Information transfer. Information must be transmitted ganisms that inhabit our planet share a common set of character- within organisms and among organisms. The survival and istics that distinguish them from nonliving things. These features function of every cell and every organism depend on the include a precise kind of organization, growth and development, orderly transmission of information. Evolution depends on self-regulated metabolism, the ability to respond to stimuli, repro- the transmission of genetic information from one generation duction, and adaptation to environmental change. to another.3. Energy for life. Energy from the sun flows through living systems from producers to consumers. All life processes, Organisms are composed of cells including the thousands of chemical transactions that main- Although they vary greatly in size and appearance, all organisms tain life’s organization, require a continuous input of energy. consist of basic units called cells. New cells are formed only by Evolution, information transmission, and energy flow are the division of previously existing cells. These concepts are ex-forces that give life its unique characteristics. We begin our study pressed in the cell theory (discussed in Chapter 4), a fundamen-of biology by developing a more precise understanding of the tal unifying concept of biology.fundamental characteristics of living systems. Some of the simplest life-forms, such as protozoa, are uni- cellular organisms, meaning that each consists of a single cellReview (❚ Fig. 1-1). In contrast, the body of a cat or a maple tree is made❚ Why are evolution, information transfer, and energy consid- of billions of cells. In such complex multicellular organisms, life ered basic to life? processes depend on the coordinated functions of component2 Chapter 1 www.thomsonedu.com/biology/solomon
    • Mike Abbey/ Visuals Unlimited 250 µm (a) Unicellular organisms consist of one intricate cell that performs McMurray Photography all the functions essential to life. Ciliates, such as this Paramecium, move about by beating their hairlike cilia. Figure 1-1 Unicellular and multicellular life-forms (b) Multicellular organisms, such as this African buffalo (Syncerus caffer) and the plants on which it grazes, may consist of billions of cells specialized to perform specific functions. cells that may be organized to form tissues, organs, and organ systems. Every cell is enveloped by a protective plasma membrane that separates it from the surrounding external environment. The ized egg that then grows and develops. The structures and body plasma membrane regulates passage of materials between cell form that develop are exquisitely adapted to the functions the and environment. Cells have specialized molecules that contain organism must perform. genetic instructions and transmit genetic information. In most cells, the genetic instructions are encoded in deoxyribonucleic acid, more simply known as DNA. Cells typically have internal Organisms regulate their structures called organelles that are specialized to perform spe- metabolic processes cific functions. There are two fundamentally different types of cells: prokary- Within all organisms, chemical reactions and energy transforma- otic and eukaryotic. Prokaryotic cells are exclusive to bacteria tions occur that are essential to nutrition, the growth and repair and to microscopic organisms called archaea. All other organisms of cells, and the conversion of energy into usable forms. The sum are characterized by their eukaryotic cells. These cells typically of all the chemical activities of the organism is its metabolism. contain a variety of organelles enclosed by membranes, including Metabolic processes occur continuously in every organism, a nucleus, which houses DNA. Prokaryotic cells are structurally and they must be carefully regulated to maintain homeostasis, an simpler; they do not have a nucleus or other membrane-enclosed appropriate, balanced internal environment. When enough of a organelles. cell product has been made, its manufacture must be decreased or turned off. When a particular substance is required, cell processes that produce it must be turned on. These homeostatic mechanisms Organisms grow and develop are self-regulating control systems that are remarkably sensitive Biological growth involves an increase in the size of individual and efficient. cells of an organism, in the number of cells, or in both. Growth The regulation of glucose (a simple sugar) concentration in may be uniform in the various parts of an organism, or it may be the blood of complex animals is a good example of a homeo- greater in some parts than in others, causing the body propor- static mechanism. Your cells require a constant supply of glucose, tions to change as growth occurs. Some organisms — most trees, which they break down to obtain energy. The circulatory system for example — continue to grow throughout their lives. Many delivers glucose and other nutrients to all the cells. When the animals have a defined growth period that terminates when a concentration of glucose in the blood rises above normal limits, characteristic adult size is reached. An intriguing aspect of the glucose is stored in the liver and in muscle cells. When you have growth process is that each part of the organism typically contin- not eaten for a few hours, the glucose concentration begins to fall. ues to function as it grows. Your body converts stored nutrients to glucose, bringing the glu- Living organisms develop as well as grow. Development in- cose concentration in the blood back to normal levels. When the cludes all the changes that take place during an organism’s life. glucose concentration decreases, you also feel hungry and restore Like many other organisms, every human begins life as a fertil- nutrients by eating. A View of Life 3
    • Organisms respond to stimuli All forms of life respond to stimuli, physical or chemical changes in their internal or external environment. Stimuli that evoke a response in most organisms are changes in the color, inten- sity, or direction of light; changes in temperature, pressure, or sound; and changes in the chemical composition of the sur- rounding soil, air, or water. Responding to stimuli involves move- Flagella ment, though not always locomotion (moving from one place to another).A. B. Dowsett /Science Photo Library/Photo Researchers, Inc. In simple organisms, the entire individual may be sensitive to stimuli. Certain unicellular organisms, for example, respond to bright light by retreating. In some organisms, locomotion is achieved by the slow oozing of the cell, the process of amoe- boid movement. Other organisms move by beating tiny, hair- like extensions of the cell called cilia or longer structures known as flagella (❚ Fig. 1-2). Some bacteria move by rotating their flagella. Most animals move very obviously. They wiggle, crawl, swim, run, or fly by contracting muscles. Sponges, corals, and oysters have free-swimming larval stages, but most are sessile as adults, 1 µm meaning that they do not move from place to place. In fact, they may remain firmly attached to a surface, such as the sea bottom or a rock. Many sessile organisms have cilia or flagella that beat Figure 1-2 Biological movement rhythmically, moving the surrounding water, which contains These bacteria (Helicobacter pylori ), equipped with flagella for the food and oxygen the organisms require. Complex animals, locomotion, have been linked to stomach ulcers. The photograph was taken using a scanning electron microscope. The bacteria are not really such as grasshoppers, lizards, and humans, have highly special- red and blue. Their color has been artificially enhanced. ized cells that respond to specific types of stimuli. For example, cells in the retina of the human eye respond to light. Although their responses may not be as obvious as those of animals, plants do respond to light, gravity, water, touch, and other stimuli. For example, plants orient their leaves to the sun and grow toward light. Many plant responses involve differ- ent growth rates of various parts of the plant body. A few plants, such as the Venus flytrap of the Carolina swamps, are very sensitive to touch and catch insects (❚ Fig. 1-3). Their leaves are David M. Dennis/ Tom Stack & Associates David M. Dennis/ Tom Stack & Associates hinged along the midrib, and they have a scent that attracts insects. Trigger hairs on the leaf surface detect the arrival of an insect and stimulate the leaf to fold. When the edges come together, they in- terlock, preventing the insect’s es- cape. The leaf then secretes enzymes (a) Hairs on the leaf surface of the Venus (b) The edges of the leaf come together and that kill and digest the insect. The flytrap (Dionaea muscipula) detect the touch interlock, preventing the fly’s escape. The leaf Venus flytrap usually grows in soil of an insect, and the leaf responds by folding. then secretes enzymes that kill and digest the insect. deficient in nitrogen. The plant ob- tains part of the nitrogen required for its growth from the insects it Figure 1-3 Plants respond to stimuli “eats.” 4 Chapter 1 www.thomsonedu.com/biology/solomon
    • Organisms reproduce ally reproducing organisms is by genetic mutation, a permanent change in the genes. At one time, people thought worms arose spontaneously from In most plants and animals, sexual reproduction is carried horsehair in a water trough, maggots from decaying meat, and out by the fusion of an egg and a sperm cell to form a fertilized frogs from the mud of the Nile. Thanks to the work of several egg (❚ Fig. 1-4b). The new organism develops from the fertilized scientists, including the Italian physician Francesco Redi in the egg. Offspring produced by sexual reproduction are the product 17th century and French chemist Louis Pasteur in the 19th cen- of the interaction of various genes contributed by the mother tury, we now know that organisms arise only from previously and the father. This genetic variation is important in the vital existing organisms. processes of evolution and adaptation. Simple organisms, such as amoebas, perpetuate themselves by asexual reproduction (❚ Fig. 1-4a). When an amoeba has grown to a certain size, it reproduces by splitting in half to form two new amoebas. Before an amoeba divides, its hereditary mate- Populations evolve and become rial (set of genes) duplicates, and one complete set is distributed adapted to the environment to each new cell. Except for size, each new amoeba is similar to The ability of a population to evolve over many generations and the parent cell. The only way that variation occurs among asexu- adapt to its environment equips it to survive in a changing world. Adaptations are inherited characteristics that enhance an organ- ism’s ability to survive in a particular environment. The long, flexible tongue of the frog is an adaptation for catching insects, the feathers and lightweight bones of birds are adaptations for flying, and the thick fur coat of the polar bear is an adaptation for surviving frigid temperatures. Adaptations may be structural, physiological, biochemical, behavioral, or a combination of all four (❚ Fig. 1-5). Every biologically successful organism is a com- plex collection of coordinated adaptations produced throughCabisco / Visuals Unlimited evolutionary processes. Review ❚ What characteristics distinguish a living organism from a nonliving object? ❚ What would be the consequences to an organism if its 100 µm homeostatic mechanisms failed? Explain your answer. (a) Asexual reproduction. One individual gives rise to two ❚ What do we mean by adaptations? or more offspring that are similar to the parent. Difflugia, a unicellular amoeba, is shown dividing to form two amoebas. McMurray Photography L. E. Gilbert /Biological Photo Service Figure 1-5 Adaptations These Burchell’s zebras (Equus burchelli), photographed at Ngoron- (b) Sexual reproduction. Typically, two parents each contribute goro Crater in Tanzania, are behaviorally adapted to position them- a gamete (sperm or egg). Gametes fuse to produce the offspring, selves to watch for lions and other predators. Stripes are thought to which has a combination of the traits of both parents. A pair of be an adaptation for visual protection against predators. They serve tropical flies are shown mating. as camouflage or to break up form when spotted from a distance. The zebra stomach is adapted for feeding on coarse grass passed over by other grazers, an adaptation that helps the animal survive when food Figure 1-4 Asexual and sexual reproduction is scarce. A View of Life 5
    • amples of organ systems. Functioning together with great preci- LEVELS OF BIOLOGICAL sion, organ systems make up a complex, multicellular organism. ORGANIZATION Again, emergent properties are evident. An organism is much more than its component organ systems.Learning Objective3 Construct a hierarchy of biological organization, including levels characteristic of individual organisms and ecological levels. Several levels of ecological organizationWhether we study a single organism or the world of life as a can be identifiedwhole, we can identify a hierarchy of biological organization Organisms interact to form still more complex levels of biologi-(❚ Fig. 1-6). At every level, structure and function are precisely cal organization. All the members of one species living in thecoordinated. One way to study a particular level is by looking at same geographic area at the same time make up a population.its components. Biologists can gain insights about cells by study- The populations of various types of organisms that inhabit a par-ing atoms and molecules. Learning about a structure by study- ticular area and interact with one another form a community. Aing its parts is called reductionism. However, the whole is more community can consist of hundreds of different types of organ-than the sum of its parts. Each level has emergent properties, isms. As populations within a community evolve, the communitycharacteristics not found at lower levels. Populations of organ- changes.isms have emergent properties such as population density, age A community together with its nonliving environment is anstructure, and birth and death rates. The individuals that make ecosystem. An ecosystem can be as small as a pond (or even aup a population do not have these characteristics. Consider also puddle) or as vast as the Great Plains of North America or thethe human brain. The brain is composed of millions of neurons Arctic tundra. All of Earth’s ecosystems together are known as the(nerve cells). We could study millions of individual neurons and biosphere. The biosphere includes all of Earth that is inhabitedhave no clue about the functional capacities of the brain. Only by living organisms — the atmosphere, the hydrosphere (water inwhen the neurons are wired together in precise fashion are the any form), and the lithosphere (Earth’s crust). The study of howemergent properties, such as the capacity for thought, judgment, organisms relate to one another and to their physical environ-and motor coordination, evident. ment is called ecology (derived from the Greek oikos, meaning “house”). ReviewOrganisms have several ❚ What are the levels of organization within an organism?levels of organization ❚ What are the levels of ecological organization?The chemical level, the most basic level of organization, includesatoms and molecules. An atom is the smallest unit of a chemicalelement that retains the characteristic properties of that element.For example, an atom of iron is the smallest possible amount ofiron. Atoms combine chemically to form molecules. Two atoms INFORMATION TRANSFERof hydrogen combine with one atom of oxygen to form a single Learning Objectivemolecule of water. Although composed of two types of atoms that 4 Summarize the importance of information transfer to livingare gases, water is a liquid with very different properties, an ex- systems, giving specific examples.ample of emergent properties. At the cell level many types of atoms and molecules associate For an organism to grow, develop, carry on self-regulated me-with one another to form cells. However, a cell is much more than tabolism, respond to stimuli, and reproduce, it must have precisea heap of atoms and molecules. Its emergent properties make it instructions and its cells must be able to communicate. The in-the basic structural and functional unit of life, the simplest com- formation an organism requires to carry on these life processesponent of living matter that can carry on all the activities neces- is coded and delivered in the form of chemical substances andsary for life. electrical impulses. Organisms must also communicate informa- During the evolution of multicellular organisms, cells asso- tion to one another.ciated to form tissues. For example, most animals have muscletissue and nervous tissue. Plants have epidermis, a tissue thatserves as a protective covering, and vascular tissues that movematerials throughout the plant body. In most complex organ- DNA transmits information fromisms, tissues organize into functional structures called organs,such as the heart and stomach in animals and roots and leaves one generation to the nextin plants. In animals, each major group of biological functions Humans give birth only to human babies, not to giraffes or rose-is performed by a coordinated group of tissues and organs called bushes. In organisms that reproduce sexually, each offspring isan organ system. The circulatory and digestive systems are ex- a combination of the traits of its parents. In 1953, James Watson6 Chapter 1 www.thomsonedu.com/biology/solomon
    • OrganismOrgan systemswork togetherin a functionalorganism. Population A population consists of organisms of the Organism same species. PopulationOrgan system Organ system(e.g., skeletalsystem) Tissuesand organs make Communityup organ systems. The populations of different species that populate theOrgan Organ same area make(e.g., bone) up a community.Tissues formorgans.Tissue Community(e.g., bone tissue)Cells associate Tissue Bone cellsto form tissues. Nucleus CellCellular level EcosystemAtoms and molecules A communityform organelles, such together withas the nucleus and the nonlivingmitochondria (the site environmentof many energy forms antransformations). ecosystem.Organelles perform Organellevarious functions Ecosystemof the cell.Chemical level Macromolecule BiosphereAtoms join to form Earth and all ofmolecules. Macro- its communities Biospheremolecules are large constitute themolecules such as biosphere.proteins and DNA. Oxygen atom Hydrogen atoms Molecule Water Figure 1-6 Animated The hierarchy of biological organization
    • isms as diverse as bacteria, frogs, and redwood trees. The genetic code is universal, that is, virtually identical in all organisms — a dramatic example of the unity of life. Information is transmitted by chemical and electrical signals Genes control the development and functioning of every or- ganism. The DNA that makes up the genes contains the “reci- pes” for making all the proteins required by the organism. Pro- teins are large molecules important in determining the structure and function of cells and tissues. For example, brain cells differ from muscle cells in large part because they have different types of proteins. Some proteins are important in communication within and among cells. Certain proteins on the surface of a cell serve as markers so that other cells “recognize” them. Some cell- surface proteins serve as receptors that combine with chemical messengers. Cells use proteins and many other types of molecules to com-Computer image of B-DNA by Geis/Stodola. Not to be reproduced without permission. municate with one another. In a multicellular organism, cells produce chemical compounds, such as hormones, that signal other cells. Hormones and other chemical messengers can signal cells in distant organs to secrete a particular required substance. In this way chemical signals help regulate growth, development, and metabolic processes. The mechanisms involved in cell sig- naling often involve complex biochemical processes. Cell signaling is currently an area of intense research. A ma- jor focus has been the transfer of information among cells of the immune system. A better understanding of how cells commu- nicate promises new insights into how the body protects itself against disease organisms. Learning to manipulate cell signaling may lead to new methods of delivering drugs into cells and new treatments for cancer and other diseases. Some organisms use electrical signals to transmit informa- tion. Most animals have nervous systems that transmit informa- Figure 1-7 DNA tion by way of both electrical impulses and chemical compounds Organisms transmit information from one generation to the next by known as neurotransmitters. Information transmitted from DNA, the hereditary material. As shown in this model, DNA consists of one part of the body to another is important in regulating life two chains of atoms twisted into a helix. Each chain consists of subunits processes. In complex animals, the nervous system gives the ani- called nucleotides. The sequence of nucleotides makes up the genetic code. mal information about its outside environment by transmitting signals from sensory receptors such as the eyes and ears to the brain. and Francis Crick worked out the structure of DNA, the large Information must also be transmitted from one organism molecule that makes up the genes, the units of hereditary mate- to another. Mechanisms for this type of communication include rial (❚ Fig. 1-7). A DNA molecule consists of two chains of at- the release of chemicals, visual displays, and sounds. Typically, oms twisted into a helix. Each chain is made up of a sequence organisms use a combination of several types of communication of chemical subunits called nucleotides. There are four types of signals. A dog may signal aggression by growling, using a par- nucleotides in DNA; and each sequence of three nucleotides is ticular facial expression, and laying its ears back. Many animals part of the genetic code. perform complex courtship rituals in which they display parts of Watson and Crick’s work led to the understanding of this ge- their bodies, often elaborately decorated, to attract a mate. netic code. The information coded in sequences of nucleotides in DNA transmits genetic information from generation to genera- Review tion. The code works somewhat like an alphabet. The nucleotides ❚ What is the function of DNA? can “spell” an amazing variety of instructions for making organ- ❚ What are two examples of cell signaling? 8 Chapter 1 www.thomsonedu.com/biology/solomon
    • TABLE 1-1 EVOLUTION: THE BASIC UNIFYING Category Cat Human White Oak CONCEPT OF BIOLOGY Domain Eukarya Eukarya Eukarya Kingdom Animalia Animalia PlantaeLearning Objectives Phylum Chordata Chordata Anthophyta5 Demonstrate the binomial system of nomenclature by using Subphylum Vertebrata Vertebrata None specific examples, and classify an organism (such as a human) in its domain, kingdom, phylum, class, order, family, genus, Class Mammalia Mammalia Eudicotyledones and species. Order Carnivora Primates Fagales6 Identify the three domains and six kingdoms of living organ- Family Felidae Hominidae Fagaceae isms, and give examples of organisms assigned to each Genus Felis Homo Quercus group. Species Felis catus Homo sapiens Quercus alba7 Give a brief overview of the theory of evolution, and explain why it is the principal unifying concept in biology.8 Apply the theory of natural selection to any given adaptation, and suggest a logical explanation of how the adaptation may have evolved. have a common gene pool (all the genes present in the popula- tion) and share a common ancestry. Closely related species areThe theory of evolution explains how populations of organisms grouped in the next broader category of classification, the genushave changed over time. This theory has become the most impor- (pl., genera).tant unifying concept of biology. We can define the term evolu- The Linnaean system of naming species is known as the bi-tion as the process by which populations of organisms change nomial system of nomenclature because each species is assignedover time. As we will discuss, evolution involves passing genes for a two-part name. The first part of the name is the genus, and thenew traits from one generation to another, leading to differences second part, the specific epithet, designates a particular speciesin populations. belonging to that genus. The specific epithet is often a descriptive The evolutionary perspective is important in every special- word expressing some quality of the organism. It is always usedized field within biology. Biologists try to understand the struc- together with the full or abbreviated generic name preceding it.ture, function, and behavior of organisms and their interactions The generic name is always capitalized; the specific epithet is gen-with one another by considering them in light of the long, con- erally not capitalized. Both names are always italicized or under-tinuing process of evolution. Although we discuss evolution in lined. For example, the domestic dog, Canis familiaris (abbrevi-depth in Chapters 18 through 22, we present a brief overview ated C. familiaris), and the timber wolf, Canis lupus (C. lupus),here to give you the background necessary to understand other belong to the same genus. The domestic cat, Felis catus, belongsaspects of biology. First we examine how biologists organize the to a different genus. The scientific name of the American whitemillions of organisms that have evolved, and then we summarize oak is Quercus alba, whereas the name of the European whitethe mechanisms that drive evolution. oak is Quercus robur. Another tree, the white willow, Salix alba, belongs to a different genus. The scientific name for our own spe- cies is Homo sapiens (“wise man”).Biologists use a binomial systemfor naming organismsBiologists have identified about 1.8 million species of extant Taxonomic classification is hierarchical(currently living) organisms and estimate that several million Just as closely related species may be grouped in a common ge-more remain to be discovered. To study life, we need a system nus, related genera can be grouped in a more inclusive group, afor organizing, naming, and classifying its myriad forms. Sys- family. Families are grouped into orders, orders into classes, andtematics is the field of biology that studies the diversity of or- classes into phyla (sing., phylum). Biologists group phyla intoganisms and their evolutionary relationships. Taxonomy, a sub- kingdoms, and kingdoms are assigned to domains. Each formalspecialty of systematics, is the science of naming and classifying grouping at any given level is a taxon (pl., taxa). Note that eachorganisms. taxon is more inclusive than the taxon below it. Together they In the 18th century Carolus Linnaeus, a Swedish botanist, form a hierarchy ranging from species to domain (❚ Table 1-1developed a hierarchical system of naming and classifying or- and ❚ Fig. 1-8).ganisms that, with some modification, is still used today. The Consider a specific example. The family Canidae, whichmost narrow category of classification is the species, a group includes all doglike carnivores (animals that eat mainly meat),of organisms with similar structure, function, and behavior. A consists of 12 genera and about 34 living species. Family Cani-species consists of one or more populations whose members are dae, along with family Ursidae (bears), family Felidae (catlikecapable of breeding with one another; in nature, they do not animals), and several other families that eat mainly meat, are allbreed with members of other species. Members of a population placed in order Carnivora. Order Carnivora, order Primates (to A View of Life 9
    • Key PointBiologists use a hierarchical classification scheme with a series of taxonomic categories from speciesto domain; each category is more general and more inclusive than the one below it. DOMAIN Eukarya KINGDOM Animalia PHYLUM Chordata CLASS Mammalia ORDER Primates FAMILY Pongidae GENUS Pan SPECIES Pan troglodytesFigure 1-8 Classification of the chimpanzee (Pan troglodytes)
    • which chimpanzees and humans belong), and several other or- Kingdom Fungi is composed of the yeasts, mildews, molds,ders belong to class Mammalia (mammals). Class Mammalia is and mushrooms. These organisms do not photosynthesize. Theygrouped with several other classes that include fishes, amphib- obtain their nutrients by secreting digestive enzymes into foodians, reptiles, and birds in subphylum Vertebrata. The vertebrates and then absorbing the predigested food. Kingdom Animalia isbelong to phylum Chordata, which is part of kingdom Animalia. made up of multicellular organisms that eat other organisms forAnimals are assigned to domain Eukarya. nutrition. Most animals exhibit considerable tissue specialization and body organization. These characters have evolved along with complex sense organs, nervous systems, and muscular systems. We have provided an introduction here to the groups ofThe tree of life includes three organisms that make up the tree of life. We will refer to them throughout this book, as we consider the many kinds of chal-domains and six kingdoms lenges organisms face and the various adaptations that haveSystematics has itself evolved as scientists have developed new evolved in response to them. We discuss the diversity of life inmolecular techniques. As researchers report new data, the classi- more detail in Chapters 23 through 31, and we summarize clas-fication of organisms changes. Systematists have developed a tree sification in Appendix B.of life, a family tree showing the relationships among organisms,that is based on similarities in the organisms’ molecules. Althoughthe tree of life is a work in progress, most biologists now assignorganisms to three domains and six kingdoms (❚ Fig. 1-9). Species adapt in response Bacteria have long been recognized as unicellular prokaryotic to changes in their environmentcells; they differ from all other organisms (except archaea) in thatthey are prokaryotes. Microbiologist Carl Woese (pronounced Every organism is the product of numerous interactions between“woes”) has been a pioneer in developing molecular approaches environmental conditions and the genes inherited from its ances-to systematics. Woese and his colleagues selected a molecule tors. If all individuals of a species were exactly alike, any changeknown as small subunit ribosomal RNA (rRNA) that functions in in the environment might be disastrous to all, and the speciesthe process of manufacturing proteins in all organisms. Because would become extinct. Adaptations to changes in the environ-its molecular structure differs somewhat in various organisms, ment occur as a result of evolutionary processes that take placeWoese hypothesized that the molecular composition of rRNA in over time and involve many generations.closely related organisms would be more similar than in distantlyrelated organisms. Woese’s findings showed that there are two distinct groupsof prokaryotes. He established the domain level of taxonomy Natural selection is an important mechanismand assigned these prokaryotes to two domains: Bacteria andArchaea. The eukaryotes, organisms with eukaryotic cells, are by which evolution proceedsclassified in domain Eukarya. Woese’s work became widely ac- Although philosophers and naturalists discussed the concept ofcepted in the mid-1990s. evolution for centuries, Charles Darwin and Alfred Wallace first In the classification system used in this book, every organism brought a theory of evolution to general attention and suggested ais assigned to a domain and to one of six kingdoms. Two king- plausible mechanism, natural selection, to explain it. In his bookdoms correspond to the prokaryotic domains: kingdom Archaea On the Origin of Species by Natural Selection, published in 1859,corresponds to domain Archaea, and kingdom Bacteria corre- Darwin synthesized many new findings in geology and biology.sponds to domain Bacteria. The remaining four kingdoms are He presented a wealth of evidence supporting his hypothesis thatassigned to domain Eukarya. present forms of life descended, with modifications, from previ- Kingdom Protista consists of protozoa, algae, water molds, ously existing forms. Darwin’s book raised a storm of controversyand slime molds. These are unicellular or simple multicellular in both religion and science, some of which still lingers.organisms. Some protists are adapted to carry out photosynthe- Darwin’s theory of evolution has helped shape the biologi-sis, the process in which light energy is converted to the chemi- cal sciences to the present day. His work generated a great wavecal energy of food molecules. Members of kingdom Plantae are of scientific observation and research that has provided muchcomplex multicellular organisms adapted to carry out photosyn- additional evidence that evolution is responsible for the greatthesis. Among characteristic plant features are the cuticle (a waxy diversity of organisms on our planet. Even today, the details ofcovering over aerial parts that reduces water loss) and stomata evolutionary processes are a major focus of investigation and(tiny openings in stems and leaves for gas exchange); many plants discussion.have multicellular gametangia (organs that protect developing re- Darwin based his theory of natural selection on the followingproductive cells). Kingdom Plantae includes both nonvascular four observations: (1) Individual members of a species show someplants (mosses) and vascular plants (ferns, conifers, and flower- variation from one another. (2) Organisms produce many moreing plants), those that have tissues specialized for transporting offspring than will survive to reproduce (❚ Fig. 1-10). (3) Organ-materials throughout the plant body. Most plants are adapted to isms compete for necessary resources such as food, sunlight, andterrestrial environments. space. Individuals with characteristics that enable them to obtain A View of Life 11
    • Three Domains: Bacteria Archaea Eukarya Six Kingdoms: Bacteria Archaea Protista Plantae Animalia Fungi R. Robinson / Visuals Unlimited Laurie Campbell /Getty Images David M. Phillips/ Visuals Unl.CNRI /Science Photo Library/ McMurray PhotographyPhoto Researchers, Inc. John Amaldi 1 µm 5 µm 10 µm (a) The large, rod- (b) These archaea (c) Unicellular (d) The plant king- (e) Among the fiercest (f) Mushrooms, such shaped bacterium (Methanosarcina protozoa (Tetra- dom claims many members of the animal as these fly agaric Bacillus anthracis, a mazei ), members of hymena) are classified beautiful and diverse kingdom, lions (Panth- mushrooms (Amanita member of kingdom the kingdom Archaea, in kingdom Protista. forms, such as the era leo) are also muscaria), belong to Bacteria, causes produce methane. lady’s slipper among the most kingdom Fungi. The anthrax, a cattle and (Phragmipedium sociable. The largest fly agaric is poison- sheep disease that caricinum). of the big cats, lions ous and causes can infect humans. live in prides (groups). delirium, raving, and profuse sweating when ingested. Common ancestor of all organisms Figure 1-9 Animated A survey of the kingdoms of life In this book, organisms are assigned to three domains and six kingdoms. and use resources are more likely to survive to reproductive ma- reproduction, a greater proportion of the population becomes turity and produce offspring. (4) The survivors that reproduce adapted to the prevailing environmental conditions. The envi- pass their adaptations for survival on to their offspring. Thus, the ronment selects the best-adapted organisms for survival. Note best-adapted individuals of a population leave, on average, more that adaptation involves changes in populations rather than in in- offspring than do other individuals. Because of this differential dividual organisms. 12 Chapter 1 www.thomsonedu.com/biology/solomon
    • DNA that persist and can be inherited. Mutations modify genes and by this process provide the raw material for evolution. Populations evolve as a result of selective pressures from changes in their environment All the genes present in a population make up its gene pool. By virtue of its gene pool, a population is a reservoir of variation. Natural selection acts on individuals within a population. Se- lection favors individuals with genes specifying traits that allow them to respond effectively to pressures exerted by the environ- ment. These organisms are most likely to survive and produce offspring. As successful organisms pass on their genetic recipe for survival, their traits become more widely distributed in the population. Over time, as populations continue to change (and asJ. Serrao/Photo Researchers, Inc. the environment itself changes, bringing different selective pres- sures), the members of the population become better adapted to their environment and less like their ancestors. As a population adapts to environmental pressures and ex- ploits new opportunities for finding food, maintaining safety, and avoiding predators, the population diversifies and new spe- cies may evolve. The Hawaiian honeycreepers, a group of re- Figure 1-10 Egg masses of the wood frog lated birds, are a good example. When honeycreeper ancestors (Rana sylvatica) first reached Hawaii, few other birds were present, so there was Many more eggs are produced than can possibly develop into adult little competition. Genetic variation among honeycreepers al- frogs. Random events are largely responsible for determining which lowed some to move into different food zones, and over time, of these developing frogs will hatch, reach adulthood, and reproduce. species with various types of bills evolved (❚ Fig. 1-11; see also However, certain traits of each organism also contribute to its prob- ability for success in its environment. Not all organisms are as prolific Chapter 20 and Fig. 20-16). Some honeycreepers now have long, as the frog, but the generalization that more organisms are produced curved bills, adapted for feeding on nectar from tubular flowers. than survive is true throughout the living world. Others have short, thick bills for foraging for insects, and still others have adapted for eating seeds. Review Darwin did not know about DNA or understand the mecha- ❚ What is the binomial system of nomenclature? nisms of inheritance. Scientists now understand that most varia- ❚ What are the three domains and six kingdoms of living tions among individuals are a result of different varieties of genes organisms? that code for each characteristic. The ultimate source of these ❚ How might you explain the sharp claws and teeth of tigers variations is random mutations, chemical or physical changes in in terms of natural selection? Jack Jeffrey, Inc. Jack Jeffrey, Inc. Jack Jeffrey, Inc. (a) The bill of this ‘Akiapola’au male (b) ‘I’iwi (Vestiaria cocciniea) in ‘ohi’a (c) Palila (Loxiodes bailleui ) in mamane tree. (Hemignathus munroi ) is adapted for blossoms. The bill is adapted for feeding This finch-billed honeycreeper feeds on extracting insect larvae from bark. The on nectar in tubular flowers. immature seeds in pods of the mamane tree. lower mandible (jaw) is used to peck at It also eats insects, berries, and young leaves. and pull off bark, whereas the maxilla (upper jaw) and tongue remove the prey. Figure 1-11 Adaptation and diversification in Hawaiian honeycreepers All three species shown here are endangered, mainly because their habitats have been destroyed by humans. A View of Life 13
    • During every energy transaction, some energy disperses into the THE ENERGY FOR LIFE environment as heat and is no longer available to the organism (❚ Fig. 1-13).Learning Objective Producers, or autotrophs, are plants, algae, and certain bac-9 Summarize the flow of energy through ecosystems, and con- teria that produce their own food from simple raw materials. trast the roles of producers, consumers, and decomposers. Most of these organisms use sunlight as an energy source and carry out photosynthesis, the process in which producers syn-Life depends on a continuous input of energy from the sun, be- thesize complex molecules from carbon dioxide and water. Thecause every activity of a living cell or organism requires energy. light energy is transformed into chemical energy, which is storedWhenever energy is used to perform biological work, some is within the chemical bonds of the food molecules produced. Oxy-converted to heat and dispersed into the environment. Recall that all the energy transformations and chemical pro-cesses that occur within an organism are referred to as its me-tabolism. Energy is necessary to carry on the metabolic activitiesessential for growth, repair, and maintenance. Each cell of an or- Lightganism requires nutrients that contain energy. Certain nutrients energyare used as fuel for cellular respiration, a process that releasessome of the energy stored in the nutrient molecules (❚ Fig. 1-12).The cell can use this energy to do work, including the synthesisof required materials, such as new cell components. Virtually allcells carry on cellular respiration. Like individual organisms, ecosystems depend on a continu- Heatous input of energy. A self-sufficient ecosystem contains threetypes of organisms — producers, consumers, and decomposers —and includes a physical environment in which they can survive. FoodThese organisms depend on one another and on the environmentfor nutrients, energy, oxygen, and carbon dioxide. However,there is a one-way flow of energy through ecosystems. Organisms Consumercan neither create energy nor use it with complete efficiency. (caterpillar) NUTRITION Consumer Nutrients (robin) Producer (plant) Some used as Some used as raw materials fuel OTHER SYNTHESIS CELLULAR ACTIVITIES Manufacture of RESPIRATION Plant litter, Dead • Homeostasis needed materials Biological process wastes bodies • Movement of and structures of breaking down materials in and molecules out of cells • Growth and Decomposers development (bacteria, fungi) Soil • Reproduction Energy Figure 1-13 Animated Energy flow Continuous energy input from the sun operates the biosphere. During photosynthesis, producers use the energy from sunlight to make com- plex molecules from carbon dioxide and water. Consumers, such as Figure 1-12 Relationships among metabolic processes the caterpillar and robin shown here, obtain energy, carbon, and otherThese processes occur continuously in the cells of living organisms. required materials when they eat producers or consumers that haveCells use some of the nutrients in food to synthesize required materi- eaten producers. Wastes and dead organic material supply decompos-als and cell parts. Cells use other nutrients as fuel for cellular respira- ers with energy and carbon. During every energy transaction, sometion, a process that releases energy stored in food. This energy is energy is lost to biological systems, dispersing into the environment asrequired for synthesis and for other forms of cell work. heat.14 Chapter 1 www.thomsonedu.com/biology/solomon
    • gen, which is required by plant cells and the cells of most otherorganisms, is produced as a by-product of photosynthesis:Carbon dioxide ϩ water ϩ light energy S sugars (food) ϩ oxygen Animals are consumers, or heterotrophs— that is, organismsthat depend on producers for food, energy, and oxygen. Consum-ers obtain energy by breaking down sugars and other food mole-cules originally produced during photosynthesis. When chemicalbonds are broken during this process of cellular respiration, theirstored energy is made available for life processes:Sugars (and other food molecules) ϩ oxygen S carbon dioxide ϩ water ϩ energy Mark Moffett /Minden PicturesConsumers contribute to the balance of the ecosystem. For ex-ample, consumers produce carbon dioxide required by produc-ers. (Note that producers also carry on cellular respiration.) Themetabolism of consumers and producers helps maintain the life-sustaining mixture of gases in the atmosphere. Most bacteria and fungi are decomposers, heterotrophs thatobtain nutrients by breaking down nonliving organic materialsuch as wastes, dead leaves and branches, and the bodies of dead Figure 1-14 Biologist at workorganisms. In their process of obtaining energy, decomposers This biologist studying the rainforest canopy in Costa Rica is part ofmake the components of these materials available for reuse. If an international effort to study and preserve tropical rain forests. Re-decomposers did not exist, nutrients would remain locked up in searchers study the interactions of organisms and the effects of human activities on the rain forests.wastes and dead bodies, and the supply of elements required byliving systems would soon be exhausted.Review tions, ask critical questions, and develop hypotheses, which are❚ What components do you think a balanced forest ecosystem tentative explanations. Using their hypotheses, scientists make might include? predictions that can be tested by making further observations❚ In what ways do consumers depend on producers? On decomposers? Include energy considerations in your or by performing experiments. They gather data, information answer. that they can analyze, often using computers and sophisticated statistical methods. They interpret the results of their experi- ments and draw conclusions from them. As we will discuss, scientists pose many hypotheses that cannot be tested by using all of the steps of the scientific method in a rigid way. Scien- THE PROCESS OF SCIENCE tists use the scientific method as a generalized framework or guide.Learning Objectives Biologists explore every imaginable aspect of life from the10 Design a study to test a given hypothesis, using the proce- structure of viruses and bacteria to the interactions of the com- dure and terminology of the scientific method. munities of our biosphere. Some biologists work mainly in11 Compare the reductionist and systems approaches to bio- logical research. laboratories, and others do their work in the field (❚ Fig. 1-14). Perhaps you will decide to become a research biologist and helpBiology is a science. The word science comes from a Latin word unravel the complexities of the human brain, discover new hor-meaning “to know.” Science is a way of thinking and a method mones that cause plants to flower, identify new species of animalsof investigating the natural world in a systematic manner. We test or bacteria, or develop new stem cell strategies to treat cancer,ideas, and based on our findings, we modify or reject these ideas. AIDS, or heart disease. Applications of basic biological researchThe process of science is investigative, dynamic, and often con- have provided the technology to transplant kidneys, livers, andtroversial. The observations made, the range of questions asked, hearts; manipulate genes; treat many diseases; and increase worldand the design of experiments depend on the creativity of the in- food production. Biology has been a powerful force in providingdividual scientist. However, science is influenced by cultural, so- the quality of life that most of us enjoy. You may choose to entercial, historical, and technological contexts, so the process changes an applied field of biology, such as environmental science, den-over time. tistry, medicine, pharmacology, or veterinary medicine. Many The scientific method involves a series of ordered steps. interesting careers in the biological sciences are discussed in theUsing the scientific method, scientists make careful observa- Careers section on our website. A View of Life 15
    • all birds have wings and fly. In this way, you can use the inductive method to organize raw data into manageable categories by an- swering this question: What do all these facts have in common? A weakness of inductive reasoning is that conclusions gen- eralize the facts to all possible examples. When we formulate the general principle, we go from many observed examples to all pos- sible examples. This is known as an inductive leap. Without it, we could not arrive at generalizations. However, we must be sensi- tive to exceptions and to the possibility that the conclusion is not valid. For example, the kiwi bird of New Zealand does not have functional wings (❚ Fig. 1-15). We can never conclusively proveC. Dani /Peter Arnold a universal generalization. The generalizations in inductive con- clusions come from the creative insight of the human mind, and creativity, however admirable, is not infallible. Figure 1-15 Is this animal a bird? The kiwi bird of New Zealand is about the size of a chicken. Its tiny 2- inch wings cannot be used for flight. The survivor of an ancient order of Scientists make careful observations birds, the kiwi has bristly, hairlike feathers and other characteristics that qualify it as a bird. and ask critical questions In 1928, British bacteriologist Alexander Fleming observed that a blue mold had invaded one of his bacterial cultures. He almost Science requires systematic discarded it, but then he noticed that the area contaminated by thought processes the mold was surrounded by a zone where bacterial colonies did not grow well. The bacteria were disease organisms of the ge- Science is systematic. Scientists organize, and often quantify, nus Staphylococcus, which can cause boils and skin infections. knowledge, making it readily accessible to all who wish to build Anything that could kill them was interesting! Fleming saved the on its foundation. In this way, science is both a personal and a mold, a variety of Penicillium (blue bread mold). He isolated the social endeavor. Science is not mysterious. Anyone who under- antibiotic penicillin from the mold. However, he had difficulty stands its rules and procedures can take on its challenges. What culturing it. distinguishes science is its insistence on rigorous methods to ex- Even though Fleming recognized the potential practical amine a problem. Science seeks to give precise knowledge about benefit of penicillin, he did not develop the chemical techniques the natural world; the supernatural is not accessible to scientific needed to purify it, and more than 10 years passed before the methods of inquiry. Science is not a replacement for philosophy, drug was put to significant use. In 1939, Sir Howard Florey and religion, or art. Being a scientist does not prevent one from par- Ernst Boris Chain developed chemical procedures to extract and ticipating in other fields of human endeavor, just as being an art- produce the active agent penicillin from the mold. Florey took ist does not prevent one from practicing science. the process to laboratories in the United States, and penicillin was first produced to treat wounded soldiers in World War II. In Deductive reasoning begins with general principles recognition of their work, Fleming, Florey, and Chain shared the Scientists use two types of systematic thought processes: deduc- 1945 Nobel Prize in Physiology or Medicine. tion and induction. With deductive reasoning, we begin with supplied information, called premises, and draw conclusions on the basis of that information. Deduction proceeds from general principles to specific conclusions. For example, if you accept the Chance often plays a role premise that all birds have wings and the second premise that in scientific discovery sparrows are birds, you can conclude deductively that sparrows have wings. Deduction helps us discover relationships among Fleming did not set out to discover penicillin. He benefited from known facts. A fact is information, or knowledge, based on the chance growth of a mold in one of his culture dishes. How- evidence. ever, we may wonder how many times the same type of mold grew on the cultures of other bacteriologists who failed to make the connection and simply threw away their contaminated cul- Inductive reasoning begins tures. Fleming benefited from chance, but his mind was prepared with specific observations to make observations and formulate critical questions, and his Inductive reasoning is the opposite of deduction. We begin with pen was prepared to publish them. Significant discoveries are specific observations and draw a conclusion or discover a general usually made by those who are in the habit of looking critically principle. For example, you know that sparrows have wings, can at nature and recognizing a phenomenon or problem. Of course, fly, and are birds. You also know that robins, eagles, pigeons, and the technology necessary for investigating the problem must also hawks have wings, can fly, and are birds. You might induce that be available. 16 Chapter 1 www.thomsonedu.com/biology/solomon
    • A hypothesis is a testable statementScientists make careful observations, ask critical questions, anddevelop hypotheses. A hypothesis is a tentative explanation forobservations or phenomena. Hypotheses can be posed as “if . . .then . . .” statements. For example, if students taking introduc-tory biology attend classes, then they will make a higher grade onthe exam than students who do not attend classes. In the early stages of an investigation, a scientist typicallythinks of many possible hypotheses. A good hypothesis exhibits Tom McHugh /Photo Researchers, Inc.the following characteristics: (1) It is reasonably consistent withwell-established facts. (2) It is capable of being tested; that is, itshould generate definite predictions, whether the results are posi-tive or negative. Test results should also be repeatable by indepen-dent observers. (3) It is falsifiable, which means it can be provenfalse, as we will discuss in the next section. After generating hypotheses, the scientist decides which, ifany, could and should be subjected to experimental test. Why Figure 1-16 Is this animal a mammal?not test them all? Time and money are important considerations The duck-billed platypus (Ornithorhynchus anatinus) is classified as ain conducting research. Scientists must establish priority among mammal because it has fur and produces milk for its young. However,the hypotheses to decide which to test first. unlike most mammals, it lays eggs.A falsifiable hypothesis can be testedIn science, a well-stated hypothesis can be tested. If no evidence Models are important in developingis found to support it, the hypothesis is rejected. The hypothesiscan be shown to be false. Even results that do not support the and testing hypotheseshypothesis may be valuable and may lead to new hypotheses. If Hypotheses have many potential sources, including direct obser-the results do support a hypothesis, a scientist may use them to vations or even computer simulations. Increasingly in biology,generate related hypotheses. hypotheses may be derived from models that scientists have de- Let us consider a hypothesis that we can test by careful ob- veloped to provide a comprehensive explanation for a large num-servation: Female mammals (animals that have hair and produce ber of observations. Examples of such testable models include themilk for their young) bear live young. The hypothesis is based on model of the structure of DNA and the model of the structure ofthe observations that dogs, cats, cows, lions, and humans all are the plasma membrane (discussed in Chapter 5).mammals and all bear live young. Consider further that a new The best design for an experiment can sometimes be estab-species, species X, is identified as a mammal. Biologists predict lished by performing computer simulations. Virtual testing andthat females of species X will bear live young. (Is this inductive or evaluation are undertaken before the experiment is performed indeductive reasoning?) If a female of the new species gives birth to the laboratory or field. Modeling and computer simulation savelive offspring, the hypothesis is supported. time and money. Before the Southern Hemisphere was explored, most peoplewould probably have accepted the hypothesis without question,because all known furry, milk-producing animals did, in fact, Many predictions can be testedbear live young. But biologists discovered that two Australiananimals (the duck-billed platypus and the spiny anteater) had fur by experimentand produced milk for their young but laid eggs (❚ Fig. 1-16). A hypothesis is an abstract idea, but based on their hypothe-The hypothesis, as stated, was false no matter how many times it ses, scientists can make predictions that can be tested. For ex-had previously been supported. As a result, biologists either had ample, we might predict that biology students who study forto consider the platypus and the spiny anteater as nonmammals 10 hours will do better on an exam than students who do notor had to broaden their definition of mammals to include them. study. As used here, a prediction is a deductive, logical conse-(They chose to do the latter.) quence of a hypothesis. It does not have to be a future A hypothesis is not true just because some of its predictions event.(the ones people happen to have thought of or have thus far been Some predictions can be tested by controlled experiments.able to test) have been shown to be true. After all, they could be Early biologists observed that the nucleus was the most promi-true by coincidence. In fact, a hypothesis can be supported by nent part of the cell, and they hypothesized that cells would bedata, but it cannot really be proven true. adversely affected if they lost their nuclei. Biologists predicted An unfalsifiable hypothesis cannot be proven false; in fact, it that if the nucleus were removed from the cell, then the cell wouldcannot be scientifically investigated. Belief in an unfalsifiable hy- die. They then experimented by surgically removing the nucleuspothesis, such as the existence of invisible and undetectable elves, of a unicellular amoeba. The amoeba continued to live and move,must be rationalized on grounds other than scientific ones. but it did not grow, and after a few days it died. These results A View of Life 17
    • suggested that the nucleus is necessary for the OBSERVATION: The nucleus is the most prominent part of the cell.metabolic processes that provide for growth ASK CRITICAL QUESTIONS: Why is the nucleus so large? What is its importance?and cell reproduction. DEVELOP HYPOTHESIS: Cells will be adversely affected if they lose their nuclei. But, the investigators asked, what if the op- MAKE A PREDICTION THAT CAN BE TESTED: If the nucleus is removed from an amoeba, the amoeba will die.eration itself, not the loss of the nucleus, caused PERFORM EXPERIMENTS TO TEST THE PREDICTION: Using a microloop,the amoeba to die? They performed a controlled researchers removed the nucleus from each amoeba in the experimental group.experiment, subjecting two groups of amoebas Amoebas in the control group were subjected to the same surgical procedure, butto the same operative trauma (❚ Fig. 1-17). In their nuclei were not removed.the experimental group, the nucleus was re-moved; in the control group, it was not. Ideally,an experimental group differs from a controlgroup only with respect to the variable beingstudied. In the control group, the researcherinserted a microloop into each amoeba andpushed it around inside the cell to simulate re-moval of the nucleus; then the instrument waswithdrawn, leaving the nucleus inside. Amoe- Amoeba diesbas treated with such a sham operation recov-ered and subsequently grew and divided, but (a) Experimental group. When its nucleus is surgicallythe amoebas without nuclei died. This experi- removed with a microloop, the amoeba dies.ment showed that the removal of the nucleus,not simply the operation, caused the death ofthe amoebas. The conclusion is that amoebascannot live without their nuclei. The resultssupport the hypothesis that if cells lose theirnuclei, they are adversely affected. The nucleusis essential for the survival of the cell. Amoeba livesResearchers must avoid bias (b) Control group. A control amoeba subjected to similar surgical procedures (including insertion of a microloop),In scientific studies, researchers must avoid bias but without actual removal of the nucleus, does not die.or preconceived notions of what should hap-pen. For example, to prevent bias, most medical RESULTS: Amoebas without nuclei died. Amoebas in the control group lived.experiments today are carried out in a double- CONCLUSION: Amoebas cannot live without their nuclei. The hypothesis is supported.blind fashion. When a drug is tested, one groupof patients receives the new medication, and a Figure 1-17 Testing a prediction regarding the importance of the nucleuscontrol group of matched patients receives aplacebo (a harmless starch pill similar in size,shape, color, and taste to the pill being tested). This is a double- Let us discuss another experiment. Research teams study-blind study, because neither the patient nor the physician knows ing chimpanzee populations in Africa have observed that chim-who is getting the experimental drug and who is getting the pla- panzees can learn specific ways to use tools from one another.cebo. The pills or treatments are coded in some way, and the code Behavior that is learned from others in a population and passedis broken only after the experiment is over and the results are to future generations is what we call culture. In the past, mostrecorded. Not all experiments can be so neatly designed; for ex- biologists have thought that only humans had culture. It has beenample, it is often difficult to establish appropriate controls. difficult to test this type of learning in the field, and the idea has been controversial. Investigators at Yerkes National Primate Re-Scientists interpret the results of search Center in Atlanta recently performed an experiment to test their hypothesis that chimpanzees can learn particular waysexperiments and make conclusions to use tools by observing other chimps (❚ Fig. 1-18).Scientists gather data in an experiment, interpret their results, The investigators predicted that if they taught one chimp toand then draw conclusions from them. In the amoeba experi- use a stick to obtain food from a dispenser, other chimps wouldment described earlier, investigators concluded that the data sup- learn the technique from the educated one. They divided chim-ported the hypothesis that the nucleus is essential for the survival panzees into two experimental groups with 16 in each group.of the cell. Even results that do not support the hypothesis may Then they taught a high-ranking female in each group to usebe valuable and may lead to new hypotheses. If the results do a stick to obtain food from an apparatus. The two chimps weresupport a hypothesis, a scientist may use them to generate related taught different methods. One chimp was taught to poke the stickhypotheses. inside the device to free the food. The other was taught to use the18 Chapter 1 www.thomsonedu.com/biology/solomon
    • OBSERVATION: African chimpanzees appear to mimic the use of tools. ASK CRITICAL QUESTIONS: Do chimpanzees learn how to use tools from one another? DEVELOP HYPOTHESIS: Chimpanzees can learn particular ways to use tools by observing other chimps. MAKE A PREDICTION THAT CAN BE TESTED: If one chimp is taught to use a stick to obtain food from a dispenser, other chimps will learn the technique from the educated chimp. PERFORM EXPERIMENTS TO TEST THE PREDICTION: One female in each of two groups of 16 chimps was educated in a specific way to use a stick to obtain food. The two educated chimps were then returned to their respective groups. In a control group, chimpanzees were not taught how to use a stick. 12 8 4 0 Control Exp. 1 Exp. 2 (a) Number of chimpanzees successfully employing specific method of tool use 12 8David Bygott 4 RESULTS: Chimps in each experimental group observed the use of the stick by the educated chimp, and a majority began to use the stick in the same way. When tested two months later, many of the 0 Control Exp. 1 Exp. 2 chimps in each group continued to use the stick. The results pre- sented here have been simplified and are based on the number of (b) Number of chimpanzees successfully employing chimps observed to use the learned method at least 10 times. All but learned method of tool use two months later one chimp in each group learned the technology, but a few used it only a few times. Some chimps taught themselves the alternative method and used that alternative. However, most conformed to the group’s use of the method that the investigator taught to the edu- Figure 1-18 Testing a prediction about learning cated chimp. in chimpanzee populations CONCLUSION: Chimpanzees learn specific ways to use tools by Wild chimpanzees are shown observing a member of their group observing other chimps. The hypothesis is supported. using a tool. stick to lift a hook that removed a blockage, allowing the food to a large majority began to use sticks in the same way. The chimps roll forward out of the device. in each group learned the specific style of using the stick that A third group served as a control group. The chimps in the their educated chimp had been taught. All but two of the chimps control group were given access to the sticks and the apparatus learned to use the stick. Two months later, the apparatus was with the food inside but were not taught how to use the sticks. All reintroduced to the chimps. Again, most of the chimps used of the control-group chimps manipulated the apparatus with the the learned technique for obtaining food. The results of the ex- stick, but none succeeded in releasing food. periment supported the hypothesis. The researchers concluded When the chimps were returned to their groups, other that chimpanzees are capable of culturally transmitting learned chimps observed how the educated chimps used the stick, and technology. A View of Life 19
    • Curtain of subjects, they are more likely to draw accurate scientific con- clusions (❚ Fig. 1-19). The scientist seeks to state with some level of confidence that any specific conclusion has a certain statistical probability of being correct. Experiments must be repeatable When researchers publish their findings in a scientific jour-Marbles Single selection nal, they typically describe their methods and procedures in sufficient detail so that other scientists can repeat the experi- produces ments. When the findings are replicated, the conclusions are, of course, strengthened. Assumption A theory is supported by tested hypotheses 100% blue Actual ratio Nonscientists often use the word theory incorrectly to refer to a 20% blue 80% white hypothesis or even to some untestable idea they wish to promote.(a) Taking a single selection can result in sampling error. If the only A theory is actually an integrated explanation of some aspect ofmarble selected is blue, we might assume all the marbles are blue. the natural world that is based on a number of hypotheses, each supported by consistent results from many observations or exper- Curtain iments. A theory relates data that previously appeared unrelated. A good theory grows, building on additional facts as they be- come known. It predicts new facts and suggests new relationships among phenomena. It may even suggest practical applications. A good theory, by showing the relationships among classes of facts, simplifies and clarifies our understanding of the natural world. As Einstein wrote, “In the whole history of science from Multiple selections Greek philosophy to modern physics, there have been constantMarbles attempts to reduce the apparent complexity of natural phenom- produce ena to simple, fundamental ideas and relations.” Developing theories is indeed a major goal of science. Assumption Many hypotheses cannot be tested by direct experiment 30% blue Actual ratio 70% white 20% blue Some well-accepted theories do not lend themselves to hypoth- 80% white esis testing by ordinary experiments. Often, these theories de-(b) The greater the number of selections we take of an unknown, scribe events that occurred in the distant past. We cannot directlythe more likely we can make valid assumptions about it. observe the origin of the universe from a very hot, dense state about 13.7 billion years ago (the Big Bang theory). However, physicists and cosmologists have been able to formulate many Figure 1-19 Animated Statistical probability hypotheses related to the Big Bang and to test many of the predic- tions derived from these hypotheses. Similarly, humans did not observe the evolution of majorSampling error can lead to inaccurate conclusions groups of organisms because that process took place over mil-One reason for inaccurate conclusions is sampling error. Be- lions of years and occurred before humans had evolved. How-cause not all cases of what is being studied can be observed or ever, many hypotheses about evolution have been posed, andtested (scientists cannot study every amoeba or every chimpan- predictions based on them have been tested. For example, if com-zee population), scientists must be content with a sample. How plex organisms evolved from simple life-forms, we would findcan scientists know whether that sample is truly representative of the fossils of the simplest organisms in the oldest strata (rock lay-whatever they are studying? If the sample is too small, it may not ers). As we explore more recent strata, we would expect to findbe representative because of random factors. A study with only increasingly complex organisms. Indeed, scientists have foundtwo, or even nine, amoebas may not yield reliable data that can be this progression of simple to complex fossils. In addition to fos-generalized to other amoebas. If researchers test a large number sils, evidence for evolution comes from many sources, including20 Chapter 1 www.thomsonedu.com/biology/solomon
    • physical and molecular similarities between organisms. Evidence Researchers working in this project identified the DNA sequencesalso comes from recent and current studies of evolution in ac- that make up the estimated 25,000 genes of the human genome,tion. Many aspects of ongoing evolution can, in fact, be studied the complete set of genes that make up the human genetic mate-in the laboratory or in the field. The evidence for evolution is so rial. Computer software developed for the Human Genome Proj-compelling that almost all scientists today accept evolution as a ect can analyze large data sets. These programs are being used towell-established theory. integrate data about protein interactions and many other aspects of molecular biology. Systems biologists view biology in terms of information systems. Increasingly, they depend on mathematics,Paradigm shifts allow new discoveries statistics, and engineering principles.A paradigm is a set of assumptions or concepts that constitutea way of thinking about reality. For example, from the time ofAristotle to the mid-19th century, biologists thought that organ-isms were either plants (kingdom Plantae) or animals (kingdom Science has ethical dimensionsAnimalia). This concept was deeply entrenched. However, with Scientific investigation depends on a commitment to practicalthe development of microscopes, investigators discovered tiny ideals, such as truthfulness and the obligation to communicatelife-forms —bacteria and protists — that were neither plant nor results. Honesty is particularly important in science. Consideranimal. Some biologists were able to make a paradigm shift, that the great (though temporary) damage done whenever an unprin-is, they changed their view of reality, to accommodate this new cipled or even desperate researcher, whose career may dependknowledge. They assigned these newly discovered organisms to on the publication of a research study, knowingly disseminatesnew kingdoms. false data. Until the deception is uncovered, researchers may devote thousands of dollars and hours of precious professional labor to futile lines of research inspired by erroneous reports.Systems biology integrates different Deception can also be dangerous, especially in medical research.levels of information Fortunately, science tends to correct itself through consistent useIn the reductionist approach to biology, researchers study the of the scientific process. Sooner or later, someone’s experimentalsimplest components of biological processes. Their goal is to results are sure to cast doubt on false data.synthesize their knowledge of many small parts to understand In addition to being ethical about their own work, scientiststhe whole. Reductionism has been (and continues to be) impor- face many societal and political issues surrounding areas suchtant in biological research. However, as biologists and their tools as genetic research, stem cell research, cloning, and human andhave become increasingly sophisticated, huge amounts of data animal experimentation. For example, some stem cells that showhave been generated, bringing the science of biology to a differ- great potential for treating human disease come from early em-ent level. bryos. The cells can be taken from 5- or 6-day-old human em- Systems biology is a field of biology that builds on infor- bryos and then cultured in laboratory glassware. (At this stage,mation provided by the reductionist approach, adding large data the embryo is a group of cells about 0.15 mm long [0.006 in].)sets generated by computers. Systems biology is also referred to Such cells could be engineered to treat failing hearts or brainsas integrative biology or integrative systems biology. Reductionism harmed by stroke, injury, Parkinson’s disease, or Alzheimer’sand systems biology are complementary approaches. Using re- disease. They could save the lives of burn victims and perhapsductionism, biologists have discovered basic information about be engineered to treat specific cancers. Scientists, and the largercomponents, such as molecules, genes, cells, and organs. Systems society, will need to determine whether the potential benefits ofbiologists, who focus on systems as a whole rather than on in- any type of research outweigh its ethical risks.dividual components, need this basic knowledge to study, for The era of the genome brings with it ethical concerns andexample, the interactions among various parts and levels of an responsibilities. How do people safeguard the privacy of geneticorganism. information? How can we be certain that knowledge of our indi- Systems biologists integrate data from various levels of com- vidual genetic codes would not be used against us when we seekplexity with the goal of understanding the big picture —how bio- employment or health insurance? Scientists must be ethicallylogical systems function. For example, systems biologists are de- responsible and must help educate people about their work, in-veloping models of different aspects of cell function. One group cluding its benefits relative to its risks. Interestingly, at the veryof researchers has developed a model consisting of nearly 8000 beginning of the Human Genome Project, part of its budget waschemical signals involved in a molecular network that leads to allocated for research on the ethical, legal, and social implicationsprogrammed cell death. By understanding cell communication, of its findings.the interactions of genes and proteins in metabolic pathways, andphysiological processes, systems biologists hope to eventually de- Reviewvelop a model of the whole organism. ❚ What are the characteristics of a good hypothesis? The development of systems biology has been fueled by the ❚ What is meant by a “controlled” experiment?huge amount of data generated by the Human Genome Project. ❚ What is systems biology? A View of Life 21
    • S UM M A RY WI T H KE Y TE RM SLearning Objectives1 Describe three basic themes of biology (page 2). tant in determining the structure and function of cells and ❚ Three basic themes of biology are evolution, transfer of tissues. information, and energy for life. The process of evolution ❚ Hormones, chemical messengers that transmit messages results in populations changing over time and explains from one part of an organism to another, are an important how the ancestry of organisms can be traced back to type of cell signaling. earlier forms of life. Information must be transmitted ❚ Many organisms use electrical signals to transmit informa- within cells, among cells, among organisms, and from one tion; most animals have nervous systems that transmit generation to the next. Life requires continuous energy electrical impulses and release neurotransmitters. from the sun. 5 Demonstrate the binomial system of nomenclature by using2 Distinguish between living and nonliving things by describing several specific examples, and classify an organism (such as the features that characterize living organisms (page 2). a human) in its domain, kingdom, phylum, class, order, family, ❚ Every living organism is composed of one or more cells. genus, and species (page 9). Living things grow by increasing the size and/or number ❚ Millions of species have evolved. A species is a group of of their cells. organisms with similar structure, function, and behavior ❚ Metabolism includes all the chemical activities that take that, in nature, breed only with one another. Members of place in the organism, including the chemical reactions a species have a common gene pool and share a common essential to nutrition, growth and repair, and conversion ancestry. of energy to usable forms. Homeostasis refers to the ap- ❚ Biologists use a binomial system of nomenclature in propriate, balanced internal environment. which the name of each species includes a genus name ❚ Organisms respond to stimuli, physical or chemical and a specific epithet. changes in their external or internal environment. Re- ❚ Taxonomic classification is hierarchical; it includes spe- sponses typically involve movement. Some organisms use cies, genus, family, order, class, phylum, kingdom, and tiny extensions of the cell, called cilia, or longer flagella domain. Each grouping is referred to as a taxon. to move from place to place. Other organisms are sessile 6 Identify the three domains and six kingdoms of living organ- and remain rooted to some surface. isms, and give examples of organisms assigned to each ❚ In asexual reproduction, offspring are typically identical group (page 9). to the single parent; in sexual reproduction, offspring are ❚ Bacteria and archaea have prokaryotic cells; all other or- the product of the fusion of gametes, and genes are typi- ganisms have eukaryotic cells. Prokaryotes make up two cally contributed by two parents. of the three domains. ❚ Populations evolve and become adapted to their environ- ❚ Organisms are classified in three domains: Archaea, Bac- ment. Adaptations are traits that increase an organism’s teria, and Eukarya; and six kingdoms: Archaea, Bacteria, ability to survive in its environment. Protista (protozoa, algae, water molds, and slime molds),3 Construct a hierarchy of biological organization, including Fungi (molds and yeasts), Plantae, and Animalia. levels characteristic of individual organisms and ecological levels (page 6). Learn more about life’s diversity by clicking ❚ Biological organization is hierarchical. A complex organism on the figure in ThomsonNOW. is organized at the chemical, cell, tissue, organ, organ 7 Give a brief overview of the theory of evolution, and explain system, and organism levels. Cells associate to form tis- why it is the principal unifying concept in biology (page 9). sues that carry out specific functions. In most multicellular organisms, tissues organize to form functional structures ❚ Evolution is the process by which populations change called organs, and an organized group of tissues and over time in response to changes in the environment. The organs form an organ system. Functioning together, organ theory of evolution explains how millions of species came systems make up a complex, multicellular organism. to be and helps us understand the structure, function, behavior, and interactions of organisms. ❚ The basic unit of ecological organization is the popula- tion. Various populations form communities; a community ❚ Natural selection, the major mechanism by which evolu- and its physical environment are an ecosystem; all of tion proceeds, favors individuals with traits that enable Earth’s ecosystems together make up the biosphere. them to cope with environmental changes. These individu- als are most likely to survive and to produce offspring. Learn more about biological organization by ❚ Charles Darwin based his theory of natural selection onclicking on the figure in ThomsonNOW. his observations that individuals of a species vary; organ- isms produce more offspring than survive to reproduce;4 Summarize the importance of information transfer to living individuals that are best adapted to their environment are systems, giving specific examples (page 6). more likely to survive and reproduce; and as successful ❚ Organisms transmit information chemically, electrically, organisms pass on their hereditary information, their traits and behaviorally. become more widely distributed in the population. ❚ DNA, which makes up the genes, is the hereditary mate- ❚ The source of variation in a population is random rial. Information encoded in DNA is transmitted from one mutation. generation to the next. DNA contains the instructions 8 Apply the theory of natural selection to any given adaptation, for the development of an organism and for carrying out and suggest a logical explanation of how the adaptation may life processes. DNA codes for proteins, which are impor- have evolved (page 9).22 Chapter 1 www.thomsonedu.com/biology/solomon
    • ❚ When the ancestors of Hawaiian honeycreepers first ing a problem or stating a critical question, developing a reached Hawaii, few other birds were present, so there hypothesis, making a prediction that can be tested, mak- was little competition for food. Through many genera- ing further observations and/or performing experiments, tions, honeycreepers with longer, more curved bills be- interpreting results, and drawing conclusions that support came adapted for feeding on nectar from tubular flowers. or falsify the hypothesis. Perhaps those with the longest, most curved bills were ❚ Deductive reasoning and inductive reasoning are two best able to survive in this food zone and lived to transmit categories of systematic thought used in the scientific their genes to their offspring. Those with shorter, thicker method. Deductive reasoning proceeds from general bills were more successful foraging for insects and passed principles to specific conclusions and helps people their genes to new generations of offspring. Eventually, discover relationships among known facts. Inductive different species evolved that were adapted to specific reasoning begins with specific observations and draws food zones. conclusions from them. Inductive reasoning helps people9 Summarize the flow of energy through ecosystems, and con- discover general principles. trast the roles of producers, consumers, and decomposers ❚ A hypothesis is a tentative explanation for observations or (page 14). phenomena. A hypothesis can be tested. If no evidence is ❚ Activities of living cells require energy; life depends on found to support it, the hypothesis is rejected. continuous energy input from the sun. During photosyn- ❚ A well-designed scientific experiment typically includes thesis, plants, algae, and certain bacteria use the energy both a control group and an experimental group and of sunlight to synthesize complex molecules from carbon must be as free as possible from bias. The control group dioxide and water. should be as closely matched to the experimental group ❚ Virtually all cells carry on cellular respiration, a biochemi- as possible. Ideally, the experimental group differs from cal process in which they capture the energy stored in the control group only with respect to the variable being nutrients by producers. Some of that energy is then used studied. to synthesize required materials or to carry out other cell activities. Do your own random sampling by clicking on ❚ A self-sufficient ecosystem includes producers, or auto- the figure in ThomsonNOW. trophs, which make their own food; consumers, which eat ❚ A theory is an integrated explanation of some aspect of producers or organisms that have eaten producers; and the natural world that is based on a number of hypoth- decomposers, which obtain energy by breaking down eses, each supported by consistent results from many wastes and dead organisms. Consumers and decomposers observations or experiments. are heterotrophs, organisms that depend on producers 11 Compare the reductionist and systems approaches to bio- as an energy source and for food and oxygen. logical research (page 15). Learn more about energy flow by clicking ❚ Using reductionism, researchers study the simplest com-on the figure in ThomsonNOW. ponents of biological processes, for example, molecules10 Design a study to test a given hypothesis, using the proce- or cells. dure and terminology of the scientific method (page 15). ❚ Systems biology uses knowledge provided by reduction- ❚ The process of science is a dynamic approach to investi- ism. Systems biologists integrate data from various levels gation. The scient ific method is a general framework that of complexity with the goal of understanding how biologi- scientists use in their work; it includes observing, recogniz- cal systems function. T E S T Y OU R UN D E RS TA ND ING 1. Metabolism (a) is the sum of all the chemical activities of 5. Cells (a) are the building blocks of living organisms (b) al- an organism (b) results from an increase in the number of ways have nuclei (c) are not found among the bacteria (d) a, cells (c) is characteristic of plant and animal kingdoms only b, and c (e) a and b (d) refers to chemical changes in an organism’s environment 6. An increase in the size or number of cells best describes (e) does not take place in producers (a) homeostasis (b) biological growth (c) chemical level of 2. Homeostasis (a) is the appropriate, balanced internal envi- organization (d) asexual reproduction (e) adaptation ronment (b) generally depends on the action of cilia (c) is the 7. DNA (a) makes up the genes (b) functions mainly to trans- long-term response of organisms to changes in their environ- mit information from one species to another (c) cannot be ment (d) occurs at the ecosystem level, not in cells or organ- changed (d) is a neurotransmitter (e) is produced during cel- isms (e) may be sexual or asexual lular respiration 3. Structures used by some organisms for locomotion are 8. Cellular respiration (a) is a process whereby sunlight is (a) cilia and nuclei (b) flagella and DNA (c) nuclei and used to synthesize cell components with the release of membranes (d) cilia and sessiles (e) cilia and flagella energy (b) occurs in heterotrophs only (c) is carried on 4. An amoeba splits into two smaller amoebas. This is an ex- by both autotrophs and heterotrophs (d) causes chemical ample of (a) locomotion (b) neurotransmission (c) asexual changes in DNA (e) occurs in response to environmental reproduction (d) sexual reproduction (e) metabolism changes A View of Life 23
    • 9. Which of the following is a correct sequence of levels of (c) genus, species, order, family, class, phylum, kingdom biological organization? (a) cell, organ, tissue, organ system (d) species, genus, family, order, class, phylum, kingdom (b) chemical, cell, organ, tissue (c) chemical, cell, tissue, (e) species, genus, order, family, class, kingdom, phylum organ (d) tissue, organ, cell, organ system (e) chemical, cell, 15. Darwin suggested that evolution takes place by (a) mutation ecosystem, population (b) changes in the individuals of a species (c) natural selection10. Which of the following is a correct sequence of levels of (d) interaction of hormones (e) homeostatic responses to biological organization? (a) organism, population, ecosystem, each change in the environment community (b) organism, population, community, ecosystem 16. A testable statement is a(an) (a) theory (b) hypothesis (c) population, biosphere, ecosystem, community (d) species, (c) principle (d) inductive leap (e) critical question population, ecosystem, community (e) ecosystem, popula- tion, community, biosphere 17. Ideally, an experimental group differs from a control group (a) only with respect to the hypothesis being tested (b) only11. Protozoa are assigned to kingdom (a) Protista (b) Fungi with respect to the variable being studied (c) in that it is less (c) Bacteria (d) Animalia (e) Plantae subject to bias (d) in that it is less vulnerable to sampling er-12. Yeasts and molds are assigned to kingdom (a) Protista ror (e) in that its subjects are more reliable (b) Fungi (c) Bacteria (d) Archaea (e) Plantae 18. A systems biologist would most likely work on (a) better un-13. In the binomial system of nomenclature, the first part of an derstanding the components of cells (b) developing a better organism’s name designates the (a) specific epithet (b) genus system of classification of organisms (c) devising a new series (c) class (d) kingdom (e) phylum of steps for the scientific method (d) researching a series of14. Which of the following is a correct sequence of levels of clas- reactions that communicate information in the cell (e) identi- sification? (a) genus, species, family, order, class, phylum, fying the connections and interactions of neurons in order to kingdom (b) genus, species, order, phylum, class, kingdom learn about brain function C R I T I C A L THI N K I N G 1. What would happen if a homeostatic mechanism failed? 5. Evolution Link. I