UNIT 1 Science, Chemistry, and Cells 1 The Scientific Study of Life 2 2 The Chemistry of Life 20 3 Cells 48 4 The Energy of Life 68 5 Photosynthesis 84 6 Respiration and Fermentation 98 UNIT 2 DNA, Inheritance, andBiotechnology 7 DNA Structure and Gene Function 112 8 DNA Replication, Binary Fission, and Mitosis 138 9 Sexual Reproduction and Meiosis 154 10 Patterns of Inheritance 170 11 DNA Technology 196 UNIT 3 Evolution and Diversity 12 Forces of Evolutionary Change 216 13 Evidence of Evolution 238 14 Speciation and Extinction 254 15 Evolution and Diversity of Microbial Life 272 16 Evolution and Diversity of Plants 300 17 Evolution and Diversity of Animals 318
UNIT 4 Ecology 18 Populations 356 19 Communities and Ecosystems 372 20 Preserving Biodiversity 402 UNIT 5 Plant Anatomy and Physiology 21 Plant Form and Function 420 22 Reproduction and Development of Flowering Plants 442 UNIT 6 Animal Anatomy and Physiology 23 Animal Tissues and Organ Systems 460 24 The Nervous System and the Senses 476 25 The Endocrine System 502 26 The Skeletal and Muscular Systems 516 27 The Circulatory and Respiratory Systems 534 28 The Digestive and Urinary Systems 556 29 The Immune System 580 30 Animal Reproduction and Development 598
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UNIT 1 Science, Chemistry,lls 1 The Scientific Study of Life 21.1 What Is Life? 3 A. Life Is Organized 5 B. Life Requires Energy 5 C. Life Maintains Internal Constancy 6 D. Life Reproduces, Grows, and Develops 6 E. Life Evolves 7 1.2 The Tree of Life Includes ThreeMain Branches 91.3 Scientists Study the Natural World 10 A. The Scientific Method Has Multiple Interrelated Parts 10 B. An Experimental Design Is a Careful Plan 12 C. Theories Are Comprehensive Explanations 13 D. Scientific Inquiry Has Limitations 14 E. Biology Continues to Advance 16 Burning Question 1.1 Are viruses alive? 8 Why We Care 1.1 It’s Hard to Know What’s Bad for You 15 Burning Question 1.2 Why am I here? 16 Investigating Life 1.1 The Orchid and the Moth 16 2 The Chemistry of Life 202.1 Atoms Make Up All Matter 21 A. Elements Are Fundamental Types of Matter 21 B. Atoms Are Particles of Elements 22 C. Isotopes Have Different Numbers of Neutrons 23 2.2 Chemical Bonds Link Atoms 24 A. Electrons Determine Bonding 25 B. In an Ionic Bond, One Atom Transfers Electrons to Another Atom 25 C. In a Covalent Bond, Atoms Share Electrons 26 D. Partial Charges on Polar Molecules Create Hydrogen Bonds 28
2.3 Water Is Essential to Life 29 A. Water Is Cohesive and Adhesive 29 B. Many Substances Dissolve in Water 29 C. Water Regulates Temperature 30 D. Water Expands As It Freezes 30 E. Water Participates in Life’s Chemical Reactions 31 2.4 Cells Have an Optimum pH 322.5 Cells Contain Four Major Types of OrganicMolecules 33 A. Large Organic Molecules Are Composed of Smaller Subunits 33 B. Carbohydrates Include Simple Sugars and Polysaccharides 34 C. Proteins Are Complex and Highly Versatile 36 D. Nucleic Acids Store and Transmit Genetic Information 38 E. Lipids Are Hydrophobic and Energy-Rich 40 Why We Care 2.1 Acids and Bases in Everyday Life 34 Burning Question 2.1 What does it mean when food is “organic” or “natural”? 35 Why We Care 2.2 Sugar Substitutes and Fake Fats 42 Burning Question 2.2 What is junk food? 43 Investigating Life 2.1 Chemical Warfare on a Tiny Battlefield 44 3 Cells 483.1 Cells Are the Units of Life 49 A. Simple Lenses Revealed the First Glimpses of Cells 49 B. Microscopes Magnify Cell Structures 49 C. All Cells Have Features in Common 51 3.2 Different Cell Types Characterize Life’s ThreeDomains 52 A. Domains Bacteria and Archaea Contain Prokaryotic Organisms 52 B. Domain Eukarya Contains Organisms with Complex Cells 53
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3.3 A Membrane Separates Each Cell from ItsSurroundings 543.4 Eukaryotic OrganellesDivide Labor 56 A. The Nucleus, Endoplasmic Reticulum, and Golgi Interact to Secrete Substances 57 B. Lysosomes, Vacuoles, and Peroxisomes Are Cellular Digestion Centers 59 C. Mitochondria Extract Energy from Nutrients 60 D. Photosynthesis Occurs in Chloroplasts 60 3.5 The Cytoskeleton Supports Eukaryotic Cells 623.6 Cells Stick Together and Communicate with OneAnother 64Burning Question 3.1 Is it possible to make an artificial cell from scratch? 55 Why We Care 3.1 Most of Your Cells Are Not Your Own 57 Investigating Life 3.1 Bacterial Magnets 65 4 The Energy of Life 684.1 All Cells Capture and UseEnergy 69 A. Energy Allows Cells to Do Life’s Work 69 B. Life Requires Energy Transformations 70 4.2 Networks of ChemicalReactions Sustain Life 71 A. Chemical Reactions Absorb or Release Energy 71 B. Linked Oxidation and Reduction Reactions Form Electron Transport Chains 71 4.3 ATP Is Cellular Energy Currency 72 A. Energy in ATP Is Critical to the Life of a Cell 72 B. ATP Represents Short-Term Energy Storage 73 4.4 Enzymes Speed Reactions 74 A. Enzymes Bring Reactants Together 74 B. Many Factors Affect Enzyme Activity 74 4.5 Membrane Transport May Release Energy or CostEnergy 75 A. Passive Transport Does Not Require Energy Input 76 B. Active Transport Requires Energy Input 78 C. Endocytosis and Exocytosis Use Vesicles to Transport Substances 79 Why We Care 4.1 Enzymes Are Everywhere 74 Burning Question 4.1 Do hand sanitizers work? 75 Investigating Life 4.1 Does Natural Selection Maintain Cystic Fibrosis? 80
5 Photosynthesis 845.1 Life Depends onPhotosynthesis 855.2 Photosynthetic Pigments CaptureSunlight 865.3 Chloroplasts Are the Sitesof Photosynthesis 875.4 Photosynthesis Occurs in Two Stages 885.5 The Light Reactions Begin Photosynthesis 89 A. Light Striking Photosystem II Provides the Energy to Produce ATP 90 B. Electrons from Photosystem I Reduce NADP+ to NADPH 91 5.6 The Carbon Reactions Produce Carbohydrates 925.7 C3, C4, and CAM Plants Use Different Carbon FixationPathways 93Burning Question 5.1 Why do leaves change colors in the fall? 89 Burning Question 5.2 Does air have mass? 91 Why We Care 5.1 Weed Killers 93 Investigating Life 5.1 Salamanders Snack on Sugars from Solar Cells 95 6 Respiration and Fermentation 986.1 Cells Use Energy in Food to MakeATP 996.2 Cellular Respiration IncludesThree Main Processes 1006.3 In Eukaryotic Cells, MitochondriaProduce Most ATP 1016.4 Glycolysis Breaks Down Glucose to Pyruvate 1026.5 Aerobic Respiration Yields Much More ATP thanGlycolysis Alone 103 A. Pyruvate Is Oxidized to Acetyl CoA 103 B. The Krebs Cycle Produces ATP and High-Energy Electron Carriers 104 C. The Electron Transport Chain Drives ATP Formation 105 6.6 How Many ATPs Can One Glucose Molecule Yield? 1066.7 Other Food Molecules Enter the Energy-ExtractingPathways 1076.8 Fermenters Acquire ATP Only in Glycolysis 108Why We Care 6.1 Some Poisons Inhibit Respiration 103 Burning Question 6.1 How do diet pills work? 105 Burning Question 6.2 What happens during hibernation? 107 Investigating Life 6.1 Hot Plants Offer Heat Rewards 109
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UNIT 2 DNA, Inheritance, and 7 DNA Structure and GeneFunction 1127.1 DNA Is a Double Helix 1137.2 DNA Stores Genetic Information:An Overview 1157.3 Transcription Uses a DNATemplate to Build RNA 1167.4 Translation Builds the Protein 118 A. Translation Requires mRNA, tRNA, and Ribosomes 118 B. Translation Occurs in Three Steps 119 C. Proteins Must Fold Correctly after Translation 120 7.5 Cells Regulate Gene Expression 121 A. Operons Are Groups of Bacterial Genes That Share One Promoter 121 B. Eukaryotic Organisms Use Many Regulatory Methods 121 7.6 Mutations Change DNA 123 A. Mutations Range from Silent to Devastating 123 B. What Causes Mutations? 124 C. Mutations Are Important for Many Reasons 125 7.7 Viruses Are Genes Wrapped in a ProteinCoat 126 A. Viruses Are Smaller and Simpler than Cells 126 B. Viral Replication Occurs in Five Stages 127 7.8 Viruses Infect All Cell Types 128 A. Bacteriophages May Kill Cells Immediately or “Hide” in a Cell 128 B. Animal Viruses May Cause Immediate Cell Death 129 C. Some Animal Viruses Linger for Years 129 D. Viruses Cause Diseases in Plants 131 7.9 Drugs and Vaccines Help Fight ViralInfections 1317.10 Viroids and Prions Are Other NoncellularInfectious Agents 132Why We Care 7.1 Poisons That Block Protein Production 120 Burning Question 7.1 Is there a gay gene? 125 Burning Question 7.2 Why do we get sick when the weather turns cold? 128 Investigating Life 7.1 Clues to the Origin of Language 133
8 DNA Replication, Binary Fission,and Mitosis 1388.1 Cells Divide and Cells Die 139 A. Sexual Life Cycles Include Mitosis, Meiosis, and Fertilization 139 B. Cell Death Is Part of Life 140 8.2 DNA Replication PrecedesCell Division 1418.3 Bacteria and Archaea Divide by Binary Fission 1428.4 Replicated Chromosomes Condense as a EukaryoticCell Prepares to Divide 1438.5 Mitotic Division Generates Exact Cell Copies 145 A. DNA Is Copied During Interphase 145 B. Chromosomes Divide During Mitosis 146 C. The Cytoplasm Splits in Cytokinesis 148 8.6 Cancer Cells Divide Uncontrollably 148 A. Chemical Signals Regulate Cell Division 148 B. Cancer Cells Are Malignant 149 C. Cancer Treatments Remove or Kill Abnormal Cells 149 D. Genes and Environment Both Can Increase Cancer Risk 150 Burning Question 8.1 Do all human cells divide at the same rate? 145 Why We Care 8.1 Skin Cancer 150 Investigating Life 8.1 Evolutionary Strategies in the Race Against Cancer 150 9 Sexual Reproduction and Meiosis 1549.1 Why Sex? 1559.2 Diploid Cells ContainTwo Homologous Sets ofChromosomes 1569.3 Meiosis Is Essentialin Sexual Reproduction 1579.4 In Meiosis, DNA Replicates Once, but the NucleusDivides Twice 1589.5 Meiosis Generates Enormous Variability 160 A. Crossing Over Shuffles Alleles 160 B. Homologous Pairs Are Oriented Randomly During Metaphase I 161 C. Random Fertilization Multiplies the Diversity 162
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9.6 Mitosis and Meiosis Have Different Functions: ASummary 1629.7 Errors Sometimes Occur in Meiosis 164 A. Polyploidy Means Extra Chromosome Sets 164 B. Nondisjunction Results in Extra or Missing Chromosomes 164 Burning Question 9.1 If mules are sterile, then how are they produced? 160 Why We Care 9.1 Multiple Births 164 Investigating Life 9.1 Evolving Germs Select for Sex in Worms 167 10 Patterns of Inheritance 17010.1 Chromosomes Are Packetsof Genetic Information: AReview 17110.2 Mendel’s ExperimentsUncovered Basic Laws ofInheritance 172 A. Dominant Alleles Appear to Mask Recessive Alleles 173 B. For Each Gene, a Cell’s Two Alleles May Be Identical or Different 174 10.3 The Two Alleles of a Gene End Up in DifferentGametes 175 A. The Simplest Punnett Squares Track the Inheritance of One Gene 175 B. Meiosis Explains Mendel’s Law of Segregation 176 10.4 Genes on Different Chromosomes Are InheritedIndependently 178 A. Tracking Two-Gene Inheritance May Require Large Punnett Squares 178 B. Meiosis Explains Mendel’s Law of Independent Assortment 178 C. The Product Rule Is a Useful Shortcut 178 10.5 Genes on the Same Chromosome May Be InheritedTogether 180 A. Genes on the Same Chromosome Are Linked 180 B. Studies of Linked Genes Have Yielded Chromosome Maps 181 10.6 Inheritance Patterns Are Rarely Simple 182 A. Incomplete Dominance and Codominance Add Phenotype Classes 182 B. Relating Genotype to Phenotype May Be Difficult 182 10.7 Sex-Linked Genes Have Unique InheritancePatterns 184 A. X-Linked Recessive Disorders Affect More Males than Females 184
B. X Inactivation Prevents “Double Dosing” of Proteins 184 10.8 Pedigrees Show Modes of Inheritance 18610.9 Most Traits Are Influenced by the Environment andMultiple Genes 188 A. The Environment Can Alter the Phenotype 188 B. Polygenic Traits Depend on More than One Gene 189 Burning Question 10.1 Why does diet soda have a warning label? 174 Burning Question 10.2 Is male baldness really from the female side of the family? 186 Why We Care 10.1 The Origin of Obesity 188 Investigating Life 10.1 Heredity and the Hungry Hordes 190 11 DNA Technology 19611.1 DNA Technology Is Changingthe World 19711.2 DNA Technology’s Tools Applyto Individual Genes or EntireGenomes 198 A. Transgenic Organisms Contain DNA from Multiple Sources 198 B. DNA Sequencing Reveals the Order of Bases 200 C. PCR Replicates DNA in a Test Tube 202 D. DNA Profiling Detects Genetic Differences 202 11.3 Stem Cells and Cloning Add New Ways to Copy Cellsand Organisms 205 A. Stem Cells Divide to Form Multiple Cell Types 205 B. Cloning Produces Identical Copies of an Organism 206 11.4 Many Medical Tests and Procedures Use DNATechnology 208 A. DNA Probes Detect Specific Sequences 208 B. Preimplantation Genetic Diagnosis Can Screen Embryos for Some Diseases 208 C. Genetic Testing Can Detect Existing Diseases 209 D. Gene Therapy Uses DNA to Treat Disease 209 E. CRISPR-Cas9 Cuts and Edits Specific Genes 210 F. Medical Uses of DNA Technology Raise Many Ethical Issues 211 Burning Question 11.1 Is selective breeding the same as genetic engineering? 198 Burning Question 11.2 What are the uses of DNA testing? 204 Why We Care 11.1 Gene Doping 211 Investigating Life 11.1 Weeds Get a Boost from Their Transgenic Cousins 212
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UNIT 3 Evolution and Divers 12 Forces of Evolutionary Change 21612.1 Evolution Acts onPopulations 21712.2 Evolutionary Thought HasEvolved for Centuries 218 A. Many Explanations Have Been Proposed for Life’s Diversity 218 B. Charles Darwin’s Voyage Provided a Wealth of Evidence 219 C. On the Origin of Species Proposed Natural Selection as an Evolutionary Mechanism 220 D. Evolutionary Theory Continues to Expand 222 12.3 Natural Selection Molds Evolution 223 A. Adaptations Enhance Reproductive Success 223 B. Natural Selection Eliminates Poorly Adapted Phenotypes 224 C. Natural Selection Does Not Have a Goal 224 D. What Does “Survival of the Fittest” Mean? 225 12.4 Evolution Is Inevitable in Real Populations 226 A. At Hardy–Weinberg Equilibrium, Allele Frequencies Do Not Change 226 B. In Reality, Allele Frequencies Always Change 227 12.5 Natural Selection Can Shape Populations inMany Ways 22812.6 Sexual Selection Directly Influences ReproductiveSuccess 23012.7 Evolution Occurs in Several Additional Ways 231 A. Mutation Fuels Evolution 231 B. Genetic Drift Occurs by Chance 231 C. Nonrandom Mating Concentrates Alleles Locally 233 D. Migration Moves Alleles Between Populations 233 Why We Care 12.1 Dogs Are Products of Artificial Selection 220 Burning Question 12.1 Is there such a thing as a “pinnacle of evolution”? 226 Why We Care 12.2 The Unending War with Bacteria 229 Investigating Life 12.1 Bacterial Evolution Goes “Hog Wild” on the Farm 234 13 Evidence of Evolution 23813.1 Clues to Evolution Lie in theEarth, Body Structures, andMolecules 23913.2 Fossils Record Evolution 241 A. The Fossil Record Is Often Incomplete 241 B. The Age of a Fossil Can Be Estimated in Two Ways 242
13.3 Biogeography Considers Species’ GeographicalLocations 243 A. The Theory of Plate Tectonics Explains Earth’s Shifting Continents 243 B. Species Distributions Reveal Evolutionary Events 244 13.4 Anatomical Comparisons May Reveal CommonDescent 245 A. Homologous Structures Have a Shared Evolutionary Origin 245 B. Vestigial Structures Have Lost Their Functions 245 C. Convergent Evolution Produces Superficial Similarities 246 13.5 Embryonic Development Patterns Provide EvolutionaryClues 24613.6 Molecules Reveal Relatedness 248 A. Comparing DNA and Protein Sequences May Reveal Close Relationships 248 B. Molecular Clocks Help Assign Dates to Evolutionary Events 249 Burning Question 13.1 Does the fossil record include transitional forms? 241 Why We Care 13.1 An Evolutionary View of the Hiccups 248 Investigating Life 13.1 Evolving Backwards 250 14 Speciation and Extinction 25414.1 What Is a Species? 255 A. Linnaeus Classified Life Based on Appearance 255 B. Species Can Be Defined Based on the Potential to Interbreed 255 14.2 Reproductive Barriers CauseSpecies to Diverge 256 A. Prezygotic Barriers Prevent Fertilization 258 B. Postzygotic Barriers Prevent Development of a Fertile Offspring 258 14.3 Spatial Patterns Define Two Types of Speciation 259 A. Allopatric Speciation Reflects a Geographical Barrier 259 B. Sympatric Speciation Occurs in a Shared Habitat 260 C. Determining the Type of Speciation May Be Difficult 261 14.4 Speciation May Be Gradual or May Occur in Bursts 26214.5 Extinction Marks the End of the Line 26314.6 Biological Classification SystemsAre Based on Common Descent 265 A. The Taxonomic Hierarchy Organizes Species into Groups 265 B. A Cladistics Approach Is Based on Shared Derived Traits 265
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C. Cladograms Depict Hypothesized Evolutionary Relationships 266 D. Many Traditional Groups Are Not Clades 267 Burning Question 14.1 Can people watch evolution and speciation in action? 258 Why We Care 14.1 Recent Species Extinctions 264 Burning Question 14.2 Did rabbits come from frogs? 267 Investigating Life 14.1 Plant Protection Rackets May Stimulate Speciation 268 15 Evolution and Diversityof Microbial Life 27215.1 Life’s Origin RemainsMysterious 273 A. The First Organic Molecules May Have Formed in a Chemical “Soup” 274 B. Clays May Have Helped Monomers Form Polymers 275 C. Membranes Enclosed the Molecules 276 D. Early Life Changed Earth Forever 276 15.2 Prokaryotes Are a Biological Success Story 277 A. What Is a Prokaryote? 277 B. Prokaryote Classification Traditionally Relies on Cell Structure and Metabolism 278 C. Prokaryotes Include Two Domains with Enormous Diversity 280 D. Bacteria and Archaea Are Essential to All Life 281 15.3 Eukaryotic Cells and Multicellularity Arose MoreThan a Billion Years Ago 284 A. Endosymbiosis Explains the Origin of Mitochondria and Chloroplasts 284 B. Multicellularity May Also Have Its Origin in Cooperation 286 15.4 Protists Are the Simplest Eukaryotes 287 A. What Is a Protist? 287 B. Algae Are Photosynthetic Protists 287 C. Some Heterotrophic Protists Were Once Classified as Fungi 289 D. Protozoa Are Diverse Heterotrophic Protists 290 15.5 Fungi Are Essential Decomposers 292 A. What Is a Fungus? 292 B. Fungal Classification Is Based on Reproductive Structures 293 C. Fungi Interact with Other Organisms 294 Burning Question 15.1 Does new life spring from simple molecules now, as it did in the past? 276 Why We Care 15.1 Antibiotics and Other Germ Killers 282 Burning Question 15.2 Are there areas on Earth where no life exists? 284
Burning Question 15.3 Why and how do algae form? 285 Why We Care 15.2 Preventing Mold 296 Investigating Life 15.1 Shining a Spotlight on Danger 297 16 Evolution and Diversity of Plants 30016.1 Plants Have Changed theWorld 301 A. Green Algae Are the Closest Relatives of Plants 301 B. Plants Are Adapted to Life on Land 303 16.2 Bryophytes Are theSimplest Plants 30616.3 Seedless Vascular Plants Have Xylem and Phloembut No Seeds 30816.4 Gymnosperms Are “Naked Seed” Plants 31016.5 Angiosperms Produce Seeds in Fruits 312Burning Question 16.1 Do all plants live on land? 303 Burning Question 16.2 What are biofuels? 304 Why We Care 16.1 Gluten and Human Health 313 Investigating Life 16.1 Genetic Messages from Ancient Ecosystems 314 17 Evolution and Diversityof Animals 31817.1 Animals Live NearlyEverywhere 319 A. What Is an Animal? 319 B. Animal Life Began in the Water 319 C. Animal Features Reflect Shared Ancestry 320 D. Biologists Also Consider Additional Characteristics 322 17.2 Sponges Are Simple Animals That Lack DifferentiatedTissues 32317.3 Cnidarians Are Radially Symmetrical, AquaticAnimals 32417.4 Flatworms Have Bilateral Symmetry and IncompleteDigestive Tracts 32517.5 Mollusks Are Soft, Unsegmented Animals 32617.6 Annelids Are Segmented Worms 32717.7 Nematodes Are Unsegmented, Cylindrical Worms 32817.8 Arthropods Have Exoskeletons and JointedAppendages 329 A. Arthropods Have Complex Organ Systems 329 B. Arthropods Are the Most Diverse Animals 330
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17.9 Echinoderm Adults Have Five-Part, Radial Symmetry 33417.10 Most Chordates Are Vertebrates 33517.11 Chordate Diversity Extends from Water to Land to Sky 337 A. Tunicates and Lancelets Are Invertebrate Chordates 337 B. Hagfishes and Lampreys Have a Cranium but Lack Jaws 338 C. Fishes Are Aquatic Vertebrates with Jaws, Gills, and Fins 338 D. Amphibians Live on Land and in Water 340 E. Reptiles Were the First Vertebrates to Thrive on Dry Land 340 F. Mammals Are Warm, Furry Milk-Drinkers 342 UNIT 4 Ecology 18 Populations 35618.1 Ecology Is the Study ofInteractions 35718.2 A Population’s Size and DensityChange Over Time 35818.3 Births and Deaths HelpDetermine Population Size 35918.4 Natural Selection Influences Life Histories 361 A. Organisms Balance Reproduction Against Other Requirements 361 B. Opportunistic and Equilibrium Life Histories Reflect the Trade-Off Between Quantity and Quality 362 18.5 Population Growth May Be Exponential or Logistic 363 A. Growth Is Exponential When Resources Are Unlimited 363 B. Population Growth Eventually Slows 364 C. Many Conditions Limit Population Size 364 18.6 The Human Population Continues to Grow 366 A. Birth and Death Rates Vary Worldwide 366 B. The Ecological Footprint Is an Estimate of Resource Use 368 Burning Question 18.1 How do biologists count animals in the open ocean? 361 Why We Care 18.1 Controlling Animal Pests 365 Investigating Life 18.1 A Toxic Compromise 369 19 Communities and Ecosystems 37219.1 Organisms InteractWithin Communities andEcosystems 37319.2 Earth Has Diverse Climates 37419.3 Biomes Are Ecosystems withDistinctive Communities ofLife 376
A. The Physical Environment Dictates Where Each Species Can Live 376 B. Terrestrial Biomes Range from the Lush Tropics to the Frozen Poles 377 C. Aquatic Biomes Include Fresh Water and the Oceans 381 19.4 Community Interactions Occur Within EachBiome 381 A. Many Species Compete for the Same Resources 382 B. Symbiotic Interactions Can Benefit or Harm a Species 383 C. Herbivory and Predation Link Species in Feeding Relationships 383 D. Closely Interacting Species May Coevolve 384 E. A Keystone Species Has a Pivotal Role in the Community 385 19.5 Succession Is a Gradual Change in a Community 38619.6 Ecosystems Require Continuous Energy Input 388 A. Food Webs Depict the Transfer of Energy and Atoms 388 B. Heat Energy Leaves Each Food Web 390 C. Harmful Chemicals May Accumulate in the Highest Trophic Levels 391 19.7 Chemicals Cycle Within Ecosystems 392 A. Water Circulates Between the Land and the Atmosphere 393 B. Autotrophs Obtain Carbon as CO2 394 C. The Nitrogen Cycle Relies on Bacteria 395 D. The Phosphorus Cycle Begins with the Weathering of Rocks 397 E. Excess Nitrogen and Phosphorus Cause Problems in Water 397 Burning Question 19.1 Why is there a “tree line” above which trees won’t grow? 377 Why We Care 19.1 What Happens After You Flush 388 Why We Care 19.2 Mercury on the Wing 390 Burning Question 19.2 Is bottled water safer than tap water? 393 Why We Care 19.3 The Nitrogen Cycle in Your Fish Tank 396 Investigating Life 19.1 Winged Migrants Sidestep Parasites 398
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20 Preserving Biodiversity 40220.1 Earth’s Biodiversity IsDwindling 40320.2 Many Human Activities DestroyHabitats 40420.3 Pollution Degrades Habitats 406 A. Water Pollution Threatens Aquatic Life 406 B. Air Pollution Causes Many Types of Damage 407 20.4 Global Climate Change Alters and Shifts Habitats 409 A. Greenhouse Gases Warm Earth’s Surface 409 B. Global Climate Change Has Severe Consequences 411 20.5 Exotic Invaders and Overexploitation DevastateMany Species 412 A. Invasive Species Displace Native Organisms 412 B. Overexploitation Can Drive Species to Extinction 413 23 Animal Tissues and OrganSystems 46023.1 Specialized Cells BuildAnimal Bodies 46123.2 Animals Consist of FourTissue Types 462 A. Epithelial Tissue Covers Surfaces 462 B. Most Connective Tissues Bind Other Tissues Together 464 C. Muscle Tissue Provides Movement 464 D. Nervous Tissue Forms a Rapid Communication Network 465 23.3 Organ Systems Are Interconnected 466 A. The Nervous and Endocrine Systems Coordinate Communication 466 B. The Skeletal and Muscular Systems Support and Move the Body 466 C. The Digestive, Circulatory, and Respiratory Systems Work Together to Acquire Energy 467 D. The Urinary, Integumentary, Immune, and Lymphatic Systems Protect the Body 467 E. The Reproductive System Produces the Next Generation 468 23.4 Organ System Interactions Promote Homeostasis 46823.5 Animals Regulate Body Temperature 469Why We Care 23.1 Two Faces of Plastic Surgery 465 Burning Question 23.1 How does the body react to food poisoning? 466 Burning Question 23.2 Can biologists build artificial organs? 471 Investigating Life 23.1 Sniffing Out the Origin of Feathers 472 24 The Nervous System and theSenses 47624.1 The Nervous System Forms aRapid CommunicationNetwork 47724.2 Neurons Are the Functional Unitsof a Nervous System 478 A. A Typical Neuron Consists of a Cell Body, Dendrites, and an Axon 478
22.5 Light Is a Powerful Influence on Plant Life 45422.6 Plants Respond to Gravity and Touch 455Burning Question 22.1 How can a fruit be seedless? 451 Why We Care 22.1 Talking Plants 452 Investigating Life 22.1 A Red Hot Chili Pepper Paradox 456 B. The Nervous System Includes Three Classes of Neurons 478 24.3 Action Potentials Convey Messages 479 A. A Neuron at Rest Has a Negative Charge 480 B. A Neuron’s Membrane Potential Reverses During an Action Potential 480 C. The Myelin Sheath Speeds Communication 482 24.4 Neurotransmitters Pass the Message from Cell toCell 48224.5 The Peripheral Nervous System Consistsof Nerve Cells Outside the Central NervousSystem 48424.6 The Central Nervous System Consists of the SpinalCord and Brain 486 A. The Spinal Cord Transmits Information Between Body and Brain 486 B. The Brain Is Divided into Several Regions 486 C. Many Brain Regions Participate in Memory 488 D. Damage to the Central Nervous System Can Be Devastating 489 24.7 The Senses Connect the Nervous System with theOutside World 490 A. Sensory Receptors Respond to Stimuli by Generating Action Potentials 490 B. Continuous Stimulation May Cause Sensory Adaptation 491 24.8 The General Senses Detect Touch, Temperature,and Pain 49124.9 The Senses of Smell and Taste DetectChemicals 49224.10 Vision Depends on Light-Sensitive Cells 49424.11 The Sense of Hearing Begins in the Ears 496Burning Question 24.1 Do neurons communicate at the speed of light? 480 Why We Care 24.1 Drugs and Neurotransmitters 484 Burning Question 24.2 Do I really use only 10% of my brain? 488 Burning Question 24.3 Do humans have pheromones? 493 Why We Care 24.2 Correcting Vision 495 Burning Question 24.4 What is an ear infection? 496 Investigating Life 24.1 Scorpion Stings Don’t Faze Grasshopper Mice 498
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25 The Endocrine System 50225.1 The Endocrine System UsesHormones to Communicate 50325.2 Hormones Stimulate Responsesin Target Cells 504 A. Water-Soluble Hormones Trigger Second Messenger Systems 504 B. Lipid-Soluble Hormones Directly Alter Gene Expression 505 25.3 The Hypothalamus and PituitaryGland Oversee Endocrine Control 505 A. The Posterior Pituitary Stores and Releases Two Hormones 507 B. The Anterior Pituitary Produces and Secretes Six Hormones 507 25.4 Hormones from Many Glands Regulate Metabolism 508 A. The Thyroid Gland Sets the Metabolic Pace 508 B. The Parathyroid Glands Control Calcium Level 509 C. The Adrenal Glands Coordinate the Body’s Stress Responses 509 D. The Pancreas Regulates Blood Glucose 510 E. The Pineal Gland Secretes Melatonin 511 25.5 Hormones from the Ovaries and Testes ControlReproduction 512Burning Question 25.1 What are endocrine disruptors? 508 Why We Care 25.1 Anabolic Steroids in Sports 512 Investigating Life 25.1 Addicted to Affection 513 26 The Skeletal and MuscularSystems 51626.1 Skeletons Take Many Forms 51726.2 The Vertebrate Skeleton Featuresa Central Backbone 51826.3 Bones Provide Support,Protect Internal Organs,and Supply Calcium 519 A. Bones Consist Mostly of Bone Tissue and Cartilage 519 B. Bone Meets Bone at a Joint 521 C. Bones Are Constantly Built and Degraded 521 D. Bones Help Regulate Calcium Homeostasis 522 26.4 Muscle Movement Requires Contractile Proteins andATP 522 A. Actin and Myosin Filaments Fill Muscle Cells 524 B. Sliding Filaments Are the Basis of Muscle Cell Contraction 524 C. Motor Neurons Stimulate Muscle Contraction 526 26.5 Muscle Cells Generate ATP in Multiple Ways 527
26.6 Muscle Fiber Types Influence Athletic Performance 528Why We Care 26.1 Bony Evidence of Murder, Illness, and Evolution 519 Burning Question 26.1 Is creatine a useful dietary supplement? 527 Burning Question 26.2 Why does heat soothe sore muscles and joints? 529 Investigating Life 26.1 Did a Myosin Gene Mutation Make Humans Brainier? 530 27 The Circulatory and RespiratorySystems 53427.1 Blood Plays a Central Role inMaintaining Homeostasis 535 A. Plasma Carries Many Dissolved Substances 536 B. Red Blood Cells Transport Oxygen 536 C. White Blood Cells Fight Infection 536 D. Blood Clotting Requires Platelets and Plasma Proteins 537 27.2 Animal Circulatory Systems Range from Simple toComplex 53827.3 Blood Circulates Through the Heart and BloodVessels 53927.4 The Human Heart Is a Muscular Pump 540 A. The Heart Has Four Chambers 540 B. The Right and Left Halves of the Heart Deliver Blood Along Different Paths 540 C. Cardiac Muscle Cells Produce the Heartbeat 541 D. Exercise Strengthens the Heart 542 27.5 Blood Vessels Form the Circulation Pathway 542 A. Arteries, Capillaries, and Veins Have Different Structures 543 B. Blood Pressure and Velocity Differ Among Vessel Types 544 27.6 The Human Respiratory System Delivers Air to theLungs 545 A. The Nose, Pharynx, and Larynx Form the Upper Respiratory Tract 546 B. The Lower Respiratory Tract Consists of the Trachea and Lungs 548 27.7 Breathing Requires Pressure Changes in the Lungs 55027.8 Red Blood Cells Carry Most Oxygen and CarbonDioxide 551Burning Question 27.1 What is the difference between donating whole blood and donating plasma? 537 Burning Question 27.2 What causes bruises? 539 Burning Question 27.3 If some exercise is good, is more exercise better? 542 Why We Care 27.1 Unhealthy Circulatory and Respiratory Systems 549 Investigating Life 27.1 In (Extremely) Cold Blood 552
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28 The Digestive and UrinarySystems 55628.1 Animals Maintain Nutrient, Water,and Ion Balance 55728.2 Digestive Systems DeriveEnergy and Raw Materials fromFood 55828.3 A Varied Diet Is Essentialto Good Health 55928.4 Body Weight Reflects Food Intake and ActivityLevel 560 A. Body Mass Index Can Identify Weight Problems 560 B. Starvation: Too Few Calories to Meet the Body’s Needs 561 C. Obesity: More Calories Than the Body Needs 561 28.5 Most Animals Have a Specialized DigestiveTract 562 A. Acquiring Nutrients Requires Several Steps 562 B. Digestive Tracts May Be Incomplete or Complete 563 C. Diet Influences Digestive Tract Structure 564 28.6 The Human Digestive System Consists of SeveralOrgans 565 A. Muscles Underlie the Digestive Tract 566 B. Digestion Begins in the Mouth 566 C. The Stomach Stores, Digests, and Churns Food 566 D. The Small Intestine Digests and Absorbs Nutrients 567 E. The Large Intestine Completes Nutrient and Water Absorption 569 28.7 Animals Eliminate Nitrogenous Wastes and RegulateWater and Ions 57028.8 The Urinary System Produces, Stores, and EliminatesUrine 57228.9 Nephrons Remove Wastes and Adjust the Compositionof Blood 573 A. Nephrons Interact Closely with Blood Vessels 573 B. Urine Formation Includes Filtration, Reabsorption, and Secretion 574 C. Hormones Regulate Kidney Function 574 Burning Question 28.1 Which diets lead to the most weight loss? 561 Burning Question 28.2 What is lactose intolerance? 568 Why We Care 28.1 The Unhealthy Digestive System 570 Why We Care 28.2 Urinary Incontinence 572 Burning Question 28.3 What can urine reveal about health and diet? 573 Why We Care 28.3 Kidney Failure, Dialysis, and Transplants 575 Investigating Life 28.1 The Cost of a Sweet Tooth 576
29 The Immune System 58029.1 Many Cells, Tissues, and OrgansDefend the Body 581 A. White Blood Cells Play Major Roles in the Immune System 581 B. The Lymphatic System Produces and Transports Many Immune System Cells 582 C. The Immune System Has Two Main Subdivisions 582 29.2 Innate Defenses Are Nonspecific and Act Early 583 A. External Barriers Form the First Line of Defense 583 B. Internal Innate Defenses Destroy Invaders 584 29.3 Adaptive Immunity Defends Against SpecificPathogens 586 A. Helper T Cells Play a Central Role in Adaptive Immunity 586 B. Cytotoxic T Cells Provide Cell-Mediated Immunity 587 C. B Cells Direct the Humoral Immune Response 588 D. The Secondary Immune Response Is Stronger Than the Primary Response 590 29.4 Vaccines Jump-Start Immunity 59029.5 Several Disorders Affect the Immune System 592 A. Autoimmune Disorders Are Devastating and Mysterious 592 B. Immunodeficiencies Lead to Opportunistic Infections 592 C. Allergies Misdirect the Immune Response 593 Why We Care 29.1 Severe Burns 584 Why We Care 29.2 Protecting a Fetus from Immune Attack 587 Burning Question 29.1 Why do we need multiple doses of some vaccines? 591 Burning Question 29.2 Can people be allergic to meat? 592 Investigating Life 29.1 The Hidden Cost of Hygiene 594 30 Animal Reproduction andDevelopment 59830.1 Animal Development Beginswith Reproduction 599 A. Reproduction Is Asexual or Sexual 599 B. Development Is Indirect or Direct 600 30.2 Males Produce Sperm Cells 601 A. Male Reproductive Organs Are Inside and Outside the Body 601 B. Spermatogenesis Yields Sperm Cells 602 C. Hormones Influence Male Reproductive Function 603
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30.3 Females Produce Egg Cells 604 A. Female Reproductive Organs Are Inside the Body 604 B. Oogenesis Yields Egg Cells 605 C. Hormones Influence Female Reproductive Function 606 D. Hormonal Fluctuations Can Cause Discomfort 607 30.4 Reproductive Health Considers Contraception andDisease 60830.5 The Human Infant Begins Life as a Zygote 611 A. Fertilization Initiates Pregnancy 611 B. The Preembryonic Stage Ends When Implantation Is Complete 612 C. Organs Take Shape During the Embryonic Stage 614 D. Organ Systems Become Functional in the Fetal Stage 615 E. Muscle Contractions in the Uterus Drive Childbirth 616 Burning Question 30.1 When can conception occur? 608 Why We Care 30.1 Substances That Cause Birth Defects 613 Investigating Life 30.1 Playing “Dress Up” on the Reef 617
Appendix A Answers to Multiple Choice Questions A-1 Appendix B Brief Guide to Statistical Significance A-2 Appendix C Units of Measure A-5 Appendix D Periodic Table of the Elements A-6 Appendix E Amino Acid Structures A-7 Appendix F Learn How to Learn A-8 Glossary G-1 Index I-1
