Understanding Biology, Fourth Edition
By Kenneth A. Mason, Tod Duncan and Jonathan B. Losos
Contents:
About the Authors iv
Changes to This Edition vi
Acknowledgments viii
A Learning Path to Understanding Biology ix
PART I The Molecular
Basis of Life 1
1 The Science of Biology 1
Concept 1.1 The Diversity of Life Is Overwhelming 2
Concept 1.2 Biology Is the Science of Life 2
Concept 1.3 Science Is Based on Both Observation and Reasoning 6
Concept 1.4 The Study of Evolution Is a Good Example
of Scientific Inquiry 9
Concept 1.5 A Few Important Concepts Form the Core
of Biology 14
Inquiry & Analysis 17
Retracing the Learning Path 18
Assessing the Learning Path 19
2 The Nature of Molecules and
the Properties of Water 21
Concept 2.1 All Matter Is Composed of Atoms 22
Concept 2.2 The Elements in Living Systems Have Low Atomic
Masses 25
Concept 2.3 Molecules Are Collections of Atoms Held Together
by Chemical Bonds 27
Concept 2.4 The Properties of Water Result from Its
Polar Nature 31
Concept 2.5 Water Molecules Can Dissociate into Ions 34
Inquiry & Analysis 36
Retracing the Learning Path 37
Assessing the Learning Path 38
3 The Chemical Building Blocks of Life 40
Concept 3.1 Carbon Provides the Framework of Biological
Molecules 41
Concept 3.2 Carbohydrates Form Both Structural and Energy-
Storing Molecules 43
Concept 3.3 Proteins Are the Tools of the Cell 47
Concept 3.4 Nucleic Acids Store and Express Genetic
Information 55
Concept 3.5 Hydrophobic Lipids Form Fats and Membranes 58
Inquiry & Analysis 61
Retracing the Learning Path 62
Assessing the Learning Path 63
PART II Biology
of the Cell 65
4 Cell Structure 65
Concept 4.1 All Living Organisms Are Composed
of Cells 66
Concept 4.2 Prokaryotic Cells Are Relatively Simple 69
Concept 4.3 Eukaryotic Cells Are Highly Compartmentalized 71
Concept 4.4 Membranes Organize the Cell Interior into Functional
Compartments 75
Concept 4.5 Mitochondria and Chloroplasts Are Energy-Processing
Organelles 79
Concept 4.6 An Internal Skeleton Supports the Shape
of Cells 81
Concept 4.7 Extracellular Structures Protect Cells 84
Concept 4.8 Cell-to-Cell Connections Determine How Adjacent
Cells Interact 86
Inquiry & Analysis 90
Retracing the Learning Path 91
Assessing the Learning Path 92
5 Membranes 94
Concept 5.1 Membranes Are Phospholipid Bilayers with
Embedded Proteins 95
Concept 5.2 Phospholipids Provide a Membrane’s Structural
Foundation 98
Concept 5.3 Membrane Proteins Enable a Broad Range of
Interactions with the Environment 99
Concept 5.4 Passive Transport Moves Molecules Across
Membranes by Diffusion 101
Concept 5.5 Active Transport Across Membranes Requires
Energy 105
Concept 5.6 Bulky Materials Cross Membranes Within
Vesicles 108
Inquiry & Analysis 111
Retracing the Learning Path 112
Assessing the Learning Path 113
6 Energy and Metabolism 115
Concept 6.1 Energy Flows Through Living Systems 116
Concept 6.2 The Laws of Thermodynamics Govern All Energy
Changes 117
Concept 6.3 ATP Is the Energy Currency of Cells 119
Concept 6.4 Enzymes Speed Up Reactions by Lowering Activation
Energy 121
Concept 6.5 Metabolism Is the Sum of a Cell’s Chemical
Activities 125
Inquiry & Analysis 127
Retracing the Learning Path 128
Assessing the Learning Path 129
7 How Cells Harvest Energy 131
Concept 7.1 Cells Harvest Energy from Organic Compounds
by Oxidation 132
Concept 7.2 Glycolysis Splits Glucose and Yields a Small Amount
of ATP 136
Concept 7.3 The Citric Acid Cycle Is the Oxidative Core of
Cellular Respiration 139
Concept 7.4 Electrons Removed by Oxidation Pass Along an
Concept 7.5 The Total Energy Yield of Aerobic Respiration Far
Exceeds That of Glycolysis 146
Concept 7.6 Aerobic Respiration Is Regulated by Feedback
Inhibition 147
Concept 7.7 Some Forms of Energy Metabolism Do Not
Require O2 148
Concept 7.8 Carbohydrates Are Not the Only Energy Source Used
by Heterotrophs 149
Inquiry & Analysis 152
Retracing the Learning Path 153
Assessing the Learning Path 154
8 Photosynthesis 156
Concept 8.1 Photosynthesis Uses Sunlight to Power the Synthesis
of Organic Molecules 157
Concept 8.2 Experiments Revealed That Photosynthesis Is a
Chemical Process 158
Concept 8.3 Pigments Capture Energy from Sunlight 160
Concept 8.4 Photosynthetic Pigments Are Organized into
Photosystems 163
Concept 8.5 Energy from Sunlight Is Used to Produce a Proton
Gradient 165
Concept 8.6 Carbon Fixation Incorporates CO2 into Organic
Molecules 170
Concept 8.7 Photorespiration Short-Circuits Photosynthesis 172
Inquiry & Analysis 175
Retracing the Learning Path 176
Assessing the Learning Path 177
9 Cell Communication 179
Concept 9.1 The Cells of Multicellular Organisms
Communicate 180
Concept 9.2 Signal Transduction Begins with Cellular Receptors 182
Concept 9.3 Intracellular Receptors Respond to Signals by
Regulating Gene Expression 184
Concept 9.4 Protein Kinase Receptors Respond to Signals by
Phosphorylating Proteins 185
Concept 9.5 G Protein–Coupled Receptors Respond to Signals
Through Effector Proteins 189
Inquiry & Analysis 194
Retracing the Learning Path 195
Assessing the Learning Path 196
10 How Cells Divide 198
Concept 10.1 Bacterial Cell Division Is Clonal 199
Concept 10.2 Eukaryotes Have Large, Linear Chromosomes 200
Concept 10.3 The Eukaryotic Cell Cycle Is Complex and Highly
Organized 203
Concept 10.4 During Interphase, Cells Grow and Prepare for
Mitosis 204
Concept 10.5 In Mitosis, Chromosomes Segregate 205
Concept 10.6 Events of the Cell Cycle Are Carefully Regulated 210
Concept 10.7 Cancer Is a Failure of Cell-Cycle Control 214
Inquiry & Analysis 217
Retracing the Learning Path 218
Assessing the Learning Path 219
PART III Genetics and
Molecular Biology 221
11 Sexual Reproduction and Meiosis 221
Concept 11.1 Sexual Reproduction Requires Meiosis 222
Concept 11.2 Meiosis Consists of Two Divisions with One Round
of DNA Replication 223
Concept 11.3 The Process of Meiosis Involves Intimate Interactions
Between Homologs 224
Concept 11.4 Meiosis Has Four Distinct Features 229
Concept 11.5 Genetic Variation Is the Evolutionary Consequence
of Sex 231
Inquiry & Analysis 232
Retracing the Learning Path 233
Assessing the Learning Path 234
12 Patterns of Inheritance 236
Concept 12.1 Experiments Carried Out by Mendel Explain
Inheritance 237
Concept 12.2 Mendel’s Principle of Segregation Accounts
for 3:1 Phenotypic Ratios 238
Concept 12.3 Mendel’s Principle of Independent Assortment
Asserts That Genes Segregate Independently 241
Concept 12.4 Probability Allows Us to Predict the Results of
Crosses 243
Concept 12.5 Extending Mendel’s Model Provides a Clearer View
of Genetics in Action 245
Concept 12.6 Genotype Dictates Phenotype by Specifying Protein
Sequences 250
Inquiry & Analysis 252
Retracing the Learning Path 253
Assessing the Learning Path 254
13 The Chromosomal Basis
of Inheritance 256
Concept 13.1 Sex Linkage and the Chromosomal Theory
of Inheritance 257
Concept 13.2 There Are Two Major Exceptions to Chromosomal
Inheritance 259
Concept 13.3 Some Genes Do Not Assort Independently:
Linkage 261
Concept 13.4 Genetic Crosses Provide Data for Genetic Maps 263
Concept 13.5 Changes in Chromosome Number Can Have Drastic
Effects 265
Concept 13.6 Inheritance in Humans Can Be Studied by Analyzing
Pedigrees 267
Inquiry & Analysis 272
Retracing the Learning Path 273
Assessing the Learning Path 274
14 DNA: The Genetic Material 276
Concept 14.1 DNA Is the Genetic Material 277
Concept 14.2 The DNA Molecule Is a Double Helix 279
Concept 14.3 Both Strands Are Copied During DNA
Replication 283
Concept 14.4 Prokaryotes Organize the Enzymes Used
to Duplicate DNA 286
Concept 14.5 Eukaryotic Chromosomes Are Large and Linear 291
Concept 14.6 Cells Repair Damaged DNA 293
Inquiry & Analysis 296
Retracing the Learning Path 297
Assessing the Learning Path 298
15 Genes and How They Work 300
Concept 15.1 Experiments Have Revealed the Nature of Genes 301
Concept 15.2 The Genetic Code Relates Information in DNA
and Protein 303
Concept 15.3 Prokaryotes Exhibit All the Basic Features
of Transcription 306
Concept 15.4 Eukaryotes Use Three Polymerases and Extensively
Modify Transcripts 309
Concept 15.5 Eukaryotic Genes May Contain Noncoding
Sequences 311
Concept 15.6 The Ribosome Is the Machine of Protein
Synthesis 313
Concept 15.7 The Process of Translation Is Complex and
Energy-Expensive 315
Concept 15.8 Mutations Are Heritable Changes in Genetic
Material 321
Inquiry & Analysis 324
Retracing the Learning Path 325
Assessing the Learning Path 326
16 Control of Gene Expression 328
Concept 16.1 All Organisms Control Expression of Their Genes 329
Concept 16.2 Regulatory Proteins Control Genes by Interacting with
Specific DNA Nucleotide Sequences 330
Concept 16.3 Prokaryotes Regulate Their Genes in Clusters 331
Concept 16.4 Transcription Factors Control Gene Transcription
in Eukaryotes 336
Concept 16.5 Chromatin Structure Affects Gene Expression 339
Concept 16.6 Eukaryotic Genes Are Also Regulated After
Transcription 341
Concept 16.7 Gene Regulation Determines How Cells Will
Develop 346
Inquiry & Analysis 350
Retracing the Learning Path 351
Assessing the Learning Path 352
17 Biotechnology 354
Concept 17.1 Enzymes Allow the Creation of Recombinant
Molecules In Vitro 355
Concept 17.2 The Polymerase Chain Reaction Is Used to Amplify
Specific DNA Sequences 359
Concept 17.3 Molecular Tools Allow Us to Analyze and Modify
Genetic Variation 362
Concept 17.4 Transgenic Organisms Are Used to Analyze Gene
Function 364
Concept 17.5 Genetic Tools Are Changing Modern Medicine 366
Concept 17.6 Genetic Engineering Is Used in Industry and
Agriculture 370
Inquiry & Analysis 375
Retracing the Learning Path 376
Assessing the Learning Path 377
18 Genomics 379
Concept 18.1 Mapping Identifies and Locates Functional Elements
in Genomes 380
Concept 18.2 The Modernization of DNA Sequencing Has
Accelerated Discovery 383
Concept 18.3 Genome Projects Reveal Insights into Medicine and
Agriculture 386
Concept 18.4 Genome Annotation Assigns Functional Information
to Genomes 388
Concept 18.5 Genome Comparisons Provide Information About
Genomic Structure and Function 391
Concept 18.6 Comparative Genomics Informs Evolutionary
Biology 396
Inquiry & Analysis 400
Retracing the Learning Path 401
Assessing the Learning Path 402
PART IV Evolution 404
19 Genes Within Populations 404
Concept 19.1 Natural Populations Exhibit Genetic Variation 405
Concept 19.2 Frequencies of Alleles Can Change 407
Concept 19.3 Five Agents Are Responsible for Evolutionary
Change 409
Concept 19.4 Selection Can Act on Traits Affected by Many
Genes 414
Concept 19.5 Natural Selection Can Be Studied Experimentally 415
Concept 19.6 Fitness Is a Measure of Evolutionary Success 418
Concept 19.7 Evolutionary Processes Sometimes Maintain
Variation 418
Concept 19.8 Sexual Selection Determines Reproductive
Success 421
Inquiry & Analysis 425
Retracing the Learning Path 426
Assessing the Learning Path 427
20 The Evidence for Evolution 429
Concept 20.1 The Beaks of Darwin’s Finches Provide Evidence of
Natural Selection 430
Concept 20.2 Peppered Moths and Industrial Melanism Illustrate
Natural Selection in Action 433
Concept 20.3 Human-Initiated Artificial Selection Is Also a
Powerful Agent of Change 434
Concept 20.4 Fossils Provide Direct Evidence of Evolution 436
Concept 20.5 Anatomical Evidence for Evolution Is Extensive
and Persuasive 440
Concept 20.6 Genes Carry a Molecular Record of the Evolutionary
Past 443
Concept 20.7 Natural Selection Favors Convergent Evolution in
Similar Environments 444
Concept 20.8 Addressing Common Criticisms of Evolutionary
Theory 446
Inquiry & Analysis 448
Retracing the Learning Path 449
Assessing the Learning Path 450
21 The Origin of Species 452
Concept 21.1 The Biological Species Concept Highlights
Reproductive Isolation 453
Concept 21.2 Natural Selection May Reinforce Reproductive
Isolation 457
Concept 21.3 Natural Selection and Genetic Drift Play Key Roles
in Speciation 459
Concept 21.4 Speciation Is Influenced by Geography 460
Concept 21.5 Adaptive Radiation Requires Both Speciation and
Habitat Diversity 462
Concept 21.6 The Pace of Evolution Varies 467
Concept 21.7 Speciation and Extinction Have Molded Biodiversity
Through Time 468
Inquiry & Analysis 470
Retracing the Learning Path 471
Assessing the Learning Path 472
PART V The Diversity
of Life 474
22 Systematics and Phylogeny 474
Concept 22.1 Systematics Reconstructs Evolutionary
Relationships 475
Concept 22.2 Cladistics Focuses on Traits Derived from a Common
Ancestor 476
Concept 22.3 Classification Is a Labeling Process, Not an
Evolutionary Reconstruction 480
Imagemore Co, Ltd./Imagemore/Getty Images
Concept 22.4 Taxonomy Attempts to Classify Organisms in an
Evolutionary Context 482
Concept 22.5 The Largest Taxa Are Domains 485
Inquiry & Analysis 490
Retracing the Learning Path 491
Assessing the Learning Path 492
23 Prokaryotes and Viruses 494
Concept 23.1 Prokaryotes Are the Most Ancient Organisms 495
Concept 23.2 Prokaryotes Have an Organized but Simple
Structure 497
Concept 23.3 The Genetics of Prokaryotes Focuses on DNA
Transfer 501
Concept 23.4 Prokaryotic Metabolism Is Diverse 504
Concept 23.5 Bacteria Cause Important Human Diseases 505
Concept 23.6 Viruses Are Not Organisms 506
Concept 23.7 Bacterial Viruses Infect by DNA Injection 510
Concept 23.8 Animal Viruses Infect by Endocytosis 511
Inquiry & Analysis 516
Retracing the Learning Path 517
Assessing the Learning Path 518
24 Protists 520
Concept 24.1 Protists, the First Eukaryotes, Arose by
Endosymbiosis 521
Concept 24.2 Protists Are a Very Diverse Group 523
Concept 24.3 The Rough Outlines of Protist Phylogeny Are
Becoming Clearer 525
Concept 24.4 Excavata Are Flagellated Protists Lacking
Mitochondria 526
Concept 24.5 SAR: Stramenopiles and Alveolates Exhibit Secondary
Endosymbiosis 529
Concept 24.6 SAR: Rhizaria Have Silicon Exoskeletons or
Limestone Shells 535
Concept 24.7 Archaeplastida Are Descended from a Single
Endosymbiosis Event 536
Concept 24.8 Amoebozoa and Opisthokonta Are Closely
Related 539
Inquiry & Analysis 542
Retracing the Learning Path 543
Assessing the Learning Path 544
25 Fungi 547
Concept 25.1 Fungi Have Unique Reproductive and Nutritional
Strategies 548
Concept 25.2 Fungi Have an Enormous Ecological Impact 550
Concept 25.3 Fungi Are Important Plant and Animal Pathogens 553
Concept 25.4 Fungi Are Taxonomically Diverse 554
Concept 25.5 Microsporidia Are Unicellular Parasites 556
Concept 25.6 Chytridiomycota and Relatives: Fungi with
Zoospores 556
Concept 25.7 Zygomycota Produce Zygotes 558
Concept 25.8 Glomeromycota Are Asexual Plant Symbionts 559
Concept 25.9 Basidiomycota Are the Mushroom Fungi 560
Concept 25.10 Ascomycota Are the Most Diverse Phylum
of Fungi 560
Inquiry & Analysis 564
Retracing the Learning Path 565
Assessing the Learning Path 566
26 Plants 568
Concept 26.1 Land Plants Are Multicellular Autotrophs Adapted
to Terrestrial Life 569
Concept 26.2 Bryophytes Have a Dominant Gametophyte
Generation 571
Concept 26.3 Seedless Vascular Plants Evolved Roots, Stems,
and Leaves 573
Concept 26.4 Lycophytes Have a Dominant Sporophyte
Generation 575
Concept 26.5 Pterophytes Are Ferns and Their Relatives 576
Concept 26.6 Seed Plants Were a Key Step in Plant Evolution 579
Concept 26.7 Gymnosperms Are Plants with “Naked Seeds” 580
Concept 26.8 Angiosperms Are Flowering Plants 584
Inquiry & Analysis 588
Retracing the Learning Path 589
Assessing the Learning Path 590
27 Animal Diversity 593
Concept 27.1 The Diversity of Animal Body Plans Arose by a Series
of Evolutionary Innovations 594
Concept 27.2 Molecular Data Are Clarifying the Animal
Phylogenetic Tree 601
Concept 27.3 True Tissue Evolved in Simple Animals 603
Concept 27.4 Flatworms and Rotifers Are Very Simple
Bilaterians 605
Concept 27.5 Mollusks and Annelids Are the Largest Groups
of Lophotrochozoans 607
Concept 27.6 Lophophorates Are Very Simple Marine
Organisms 611
Concept 27.7 Nematodes and Arthropods Are Both Large Groups
of Ecdysozoans 612
Concept 27.8 Deuterostomes Are Composed of Echinoderms and
Chordates 617
Inquiry & Analysis 620
Retracing the Learning Path 621
Assessing the Learning Path 623
28 Vertebrates 625
Concept 28.1 Nonvertebrate Chordates Do Not Form Bone 626
Concept 28.2 Almost All Chordates Are Vertebrates 627
Concept 28.3 Fishes Are the Earliest and Most Diverse
Vertebrates 627
Concept 28.4 Amphibians Are Moist-Skinned Descendants of the
Early Tetrapods 632
Concept 28.5 Reptiles Are Fully Adapted to Terrestrial Living 633
Concept 28.6 Birds Are Essentially Flying Reptiles 637
Concept 28.7 Mammals Are the Least Diverse of Vertebrates 640
Concept 28.8 Primates Include Lemurs, Monkeys, Apes, and
Humans 643
Inquiry & Analysis 650
Retracing the Learning Path 651
Assessing the Learning Path 652
PART VI Plant Form
and Function 655
29 Plant Form 655
Concept 29.1 Meristems Articulate the Body Plan 656
Concept 29.2 Plants Contain Three Main Tissues 659
Concept 29.3 Roots Have Four Growth Zones 664
Concept 29.4 Stems Provide Support for Aboveground Organs 669
Concept 29.5 Leaves Are a Plant’s Photosynthetic Organs 673
Inquiry & Analysis 676
Retracing the Learning Path 677
Assessing the Learning Path 678
30 Flowering Plant Reproduction 680
Concept 30.1 Reproduction Starts with Flowering 681
Concept 30.2 Flowers Attract Pollinators 683
Concept 30.3 Fertilization Leads to Embryogenesis 688
Concept 30.4 Seeds Protect Angiosperm Embryos 690
Concept 30.5 Fruits Promote Seed Dispersal 692
Concept 30.6 Germination Begins Seedling Growth 693
Concept 30.7 Plant Life Spans Vary Widely 696
Concept 30.8 Asexual Reproduction Is Common Among Flowering
Plants 697
Inquiry & Analysis 700
Retracing the Learning Path 701
Assessing the Learning Path 702
31 The Living Plant 705
Concept 31.1 Water Moves Through Plants Based on Potential
Differences 706
Concept 31.2 Roots Absorb Minerals and Water 709
Concept 31.3 Xylem Transports Water from Root to Shoot 711
Concept 31.4 Transpiration Rate Reflects Environmental
Conditions 713
Concept 31.5 Plants Are Adapted to Water Stress 715
Concept 31.6 Phloem Transports Organic Molecules 716
Concept 31.7 Plants Require a Variety of Nutrients 717
Concept 31.8 Plants Use Hormones to Regulate Growth 719
Concept 31.9 Plant Growth Is Responsive to Light 724
Concept 31.10 Plant Growth Is Sensitive to Gravity 727
Inquiry & Analysis 730
Retracing the Learning Path 731
Assessing the Learning Path 733
PART VII Animal Form
and Function 735
32 The Animal Body and How It Moves 735
Concept 32.1 The Vertebrate Body Has a Hierarchical
Organization 736
Concept 32.2 Epithelial Tissue Covers Body Surfaces 738
Concept 32.3 Nerve Tissue Conducts Signals Rapidly 740
Concept 32.4 Connective Tissue Supports the Body 740
Concept 32.5 Muscle Tissue Powers the Body’s Movements 742
Concept 32.6 Skeletal Systems Anchor the Body’s Muscles 744
Concept 32.7 Vertebrate Endoskeletons Are Made of Bone 745
Concept 32.8 Muscles Contract Because Their Myofilaments
Slide 749
Concept 32.9 Animal Locomotion Takes Many Forms 753
Inquiry & Analysis 756
Retracing the Learning Path 757
Assessing the Learning Path 758
33 The Nervous System 760
Concept 33.1 The Nervous System Directs the Body’s Actions 761
Concept 33.2 Neurons Maintain a Resting Potential Across the
Plasma Membrane 762
Concept 33.3 Action Potentials Propagate Nerve Impulses 764
Concept 33.4 Synapses Are Where Neurons Communicate with
Other Cells 766
Concept 33.5 The Central Nervous System Includes the Brain
and Spinal Cord 769
Concept 33.6 The Peripheral Nervous System Consists of Both
Sensory and Motor Neurons 771
Concept 33.7 Sensory Receptors Provide Information About the
Body’s Environment 773
Concept 33.8 Mechanoreceptors Sense Touch and Pressure 774
Concept 33.9 Sounds and Body Position Are Sensed by Vibration
Detectors 775
Concept 33.10 Taste, Smell, and pH Senses Utilize
Chemoreceptors 778
Concept 33.11 Vision Employs Photoreceptors to Perceive Objects
at a Distance 779
Inquiry & Analysis 785
Retracing the Learning Path 786
Assessing the Learning Path 787
34 Fueling the Body’s Metabolism 789
Concept 34.1 Vertebrate Digestive Systems Are Tubular Tracts 790
Concept 34.2 Food Is Processed as It Passes Through the Digestive
Tract 791
Concept 34.3 The Digestive Tract Is Regulated by the Nervous
System and Hormones 796
Concept 34.4 Respiratory Systems Promote Efficient Exchange of
Gases 797
Concept 34.5 Gills Provide for Efficient Gas Exchange in Water 798
Stockbyte/Getty Images
Concept 34.6 Lungs Are the Respiratory Organs of Terrestrial
Vertebrates 800
Concept 34.7 Oxygen and Carbon Dioxide Are Transported by
Fundamentally Different Mechanisms 803
Concept 34.8 Circulating Blood Carries Metabolites and Gases
to the Tissues 806
Concept 34.9 Vertebrate Circulatory Systems Put a Premium on
Efficient Circulation 808
Concept 34.10 The Four Chambers of the Heart Contract in
a Cycle 811
Concept 34.11 The Circulatory Highway Is Composed of Arteries,
Capillaries, and Veins 814
Inquiry & Analysis 817
Retracing the Learning Path 818
Assessing the Learning Path 820
35 Maintaining Homeostasis 822
Concept 35.1 Homeostasis Maintains a Constant Internal
Environment 823
Concept 35.2 Hormones Are Chemical Messages That Direct Body
Processes 827
Concept 35.3 The Pituitary and the Hypothalamus Are the Body’s
Control Centers 831
Concept 35.4 Peripheral Endocrine Glands Play Major Roles in
Homeostasis 834
Concept 35.5 Animals Are Osmoconformers or Osmoregulators 838
Concept 35.6 The Kidney Maintains Osmotic Homeostasis in
Mammals 839
Concept 35.7 Hormones Control Osmoregulation 844
Concept 35.8 The Immune System Defends the Body 845
Concept 35.9 Cell-Mediated Immunity Involves Helper and Killer
T Cells 850
Concept 35.10 In Humoral Immunity, B Cells Produce Protective
Antibodies 852
Inquiry & Analysis 856
Retracing the Learning Path 857
Assessing the Learning Path 859
36 Reproduction and Development 861
Concept 36.1 Mammals Are Viviparous 862
Concept 36.2 The Human Male Reproductive System Is Typical
of Mammals 863
Concept 36.3 The Human Female Reproductive System Undergoes
Cyclic Gamete Development 866
Concept 36.4 The First Step in Development Is Fertilization 871
Concept 36.5 Cells of the Early Embryo Are Totipotent 874
Concept 36.6 Cleavage Leads to the Blastula Stage 878
Concept 36.7 Gastrulation Forms the Basic Body Plan
of the Embryo 880
Concept 36.8 The Body’s Organs Form in Organogenesis 882
Concept 36.9 Human Development Takes Nine Months 885
Inquiry & Analysis 889
Retracing the Learning Path 890
Assessing the Learning Path 891
PART VIII Ecology
and Behavior 893
37 Behavioral Biology 893
Concept 37.1 An Animal’s Genome Influences Its Behavior 894
Concept 37.2 Learning Also Influences Behavior 896
Concept 37.3 Thinking Directs the Behavior of Many Animals 897
Concept 37.4 Migratory Behavior Is Both Innate and Learned 898
Concept 37.5 Animal Communication Plays a Key Role in
Ecological and Social Behavior 900
Concept 37.6 Behavior Evolves Adaptively 903
Concept 37.7 Behavioral Ecology Examines the Adaptive
Significance of Behaviors 904
Concept 37.8 Behavioral Strategies Have Evolved to Maximize
Reproductive Success 907
Concept 37.9 Some Behaviors Decrease Fitness to Benefit Other
Individuals 909
Concept 37.10 Group Living Has Evolved in Both Insects and
Vertebrates 912
Inquiry & Analysis 914
Retracing the Learning Path 915
Assessing the Learning Path 916
38 Ecology of Individuals and
Populations 919
Concept 38.1 Populations Are Groups of a Single Species in
One Place 920
Concept 38.2 Population Growth Depends upon Members’ Age
and Sex 923
Concept 38.3 Evolution Favors Life Histories That Maximize
Lifetime Reproductive Success 926
Concept 38.4 Environment Limits Population Growth 928
Concept 38.5 Resource Availability Regulates Population
Growth 930
Concept 38.6 Earth’s Human Population Is Growing
Explosively 933
Concept 38.7 Pandemics and Human Health 936
Inquiry & Analysis 939
Retracing the Learning Path 940
Assessing the Learning Path 942
Mike Powles/Getty Images
39 Community Ecology and Ecosystem
Dynamics 944
Concept 39.1 Competition Shapes How Species Live Together in
Communities 945
Concept 39.2 Predator–Prey Relationships Foster Coevolution 949
Concept 39.3 Cooperation Among Species Can Lead to
Coevolution 953
Concept 39.4 Ecological Succession Is a Consequence of Habitat
Alteration 958
Concept 39.5 Chemical Elements Move Through Ecosystems in
Biogeochemical Cycles 959
Concept 39.6 Energy Flows Through Ecosystems in One
Direction 965
Concept 39.7 Biodiversity May Increase Ecosystem Stability 969
Inquiry & Analysis 974
Retracing the Learning Path 975
Assessing the Learning Path 977
40 The Living World 979
Concept 40.1 Ecosystems Are Shaped by Sun, Wind, and
Water 980
Concept 40.2 Earth Has 14 Major Terrestrial Ecosystems, Called
Biomes 984
Concept 40.3 Freshwater Habitats Occupy Less Than 2% of Earth’s
Surface 986
Concept 40.4 Marine Habitats Dominate the Earth 987
Concept 40.5 Humanity’s Pollution Is Severely Impacting the
Biosphere 989
Concept 40.6 Human Activity Is Altering Earth’s Climate 991
Inquiry & Analysis 996
Retracing the Learning Path 997
Assessing the Learning Path 999
Appendix: Answer Key A-1
Index I-1