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Contents Preface xxi 1 An Introduction to Life on Earth 000 Case Study: Life on Earth-and Elsewhere? 000 1.1 How Do Scientists Study Life? 000 Life Can Be Studied at Different Levels of Organization 000 Scientific Principles Underlie All Scientific Inquiry 000 The Scientific Method Is the Basis for Scientific Inquiry 000 Communication Is Crucial to Science 000 Scientific Inquiry: Controlled Experiments, Then and Now 000 Science Is a Human Endeavor 000 Scientific Theories Have Been Thoroughly Tested 000 1.2 Evolution: The Unifying Theory of Biology 000 Three Natural Processes Underlie Evolution 000 Earth Watch: Why Preserve Biodiversity? 000 1.3 What Are the Characteristics of Living Things? 000 Links to Life: The Life Around Us 000 Living Things Are Complex, Organized, and Composed of Cells 000 Living Things Maintain Relatively Constant Internal Conditions Through Homeostasis 000 Living Things Respond to Stimuli 000 Living Things Acquire and Use Materials and Energy 000 Living Things Grow 000 Living Things Reproduce Themselves 000 Living Things, Collectively, Have the Capacity to Evolve 000 1.4 How Do Scientists Categorize the Diversity of Life? 000 The Domains Bacteria and Archaea Consist of Prokaryotic Cells; the Domain Eukarya Is Composed of Eukaryotic Cells 000 Bacteria, Archaea, and Protists Are Mostly Unicellular; Members of the Kingdoms Fungi, Plantae, and Animalia Are Primarily Multicellular 000 Members of the Different Kingdoms Have Different Ways of Acquiring Energy 000 1.5 How Does Knowledge of Biology Illuminate Everyday Life? 000 Case Study Revisited: Life on Earth-and Elsewhere? 000 UNIT ONE The Life of a Cell 000 2 Atoms, Molecules, and Life 000 Case Study: Walking on Water 2.1 What Are Atoms? Atoms, the Basic Structural Units of Matter, Are Composed of Still Smaller Particles Scientific Inquiry: Radioactivity in Research 2.2 How Do Atoms Interact to Form Molecules? Atoms Interact with Other Atoms When There Are Vacancies in Their Outermost Electron Shells Charged Atoms Called Ions Interact to Form Ionic Bonds Uncharged Atoms Can Become Stable by Sharing Electrons, Forming Covalent Bonds Hydrogen Bonds Are Weaker Electrical Attractions Between or Within Molecules with Polar Covalent Bonds Links to Life: Health Food? 2.3 Why Is Water So Important to Life? Water Interacts with Many Other Molecules Water Molecules Tend to Stick Together Water-Based Solutions Can Be Acidic, Basic, or Neutral Water Moderates the Effects of Temperature Changes Water Forms an Unusual Solid: Ice Case Study Revisited: Walking on Water 3 Biological Molecules 000 Case Study: Puzzling Proteins 3.1 Why Is Carbon So Important in Biological Molecules? 3.2 How Are Organic Molecules Synthesized? Biological Molecules Are Joined Together or Broken Apart by Removing or Adding Water 3.3 What Are Carbohydrates? There Are Several Monosaccharides with Slightly Different Structures Disaccharides Consist of Two Single Sugars Linked by Dehydration Synthesis Links to Life: Health Foods? Polysaccharides Are Chains of Single Sugars 3.4 What Are Lipids? Oils, Fats, and Waxes Are Lipids Containing Only Carbon, Hydrogen, and Oxygen Phospholipids Have Water-Soluble "Heads" and Water-Insoluble "Tails" Steroids Consist of Four Carbon Rings Fused Together Health Watch: Cholesterol-Friend and Foe 3.5 What Are Proteins? Proteins Are Formed from Chains of Amino Acids Amino Acids Are Joined to Form Chains by Dehydration Synthesis A Protein Can Have Up to Four Levels of Structure The Functions of Proteins Are Linked to Their Three-Dimensional Structures A Closer Look: A Hairy Subject 3.6 What Are Nucleic Acids? DNA and RNA, the Molecules of Heredity, Are Nucleic Acids Other Nucleotides Act as Intracellular Messengers and Energy Carriers Case Study Revisited: Puzzling Proteins 4 Cell Structure and Function 000 Case Study: Spare Parts for Human Bodies 4.1 What Is the Cell Theory? 4.2 What Are the Basic Attributes of Cells? Cell Function Limits Cell Size All Cells Share Common Features Scientific Inquiry: The Search for the Cell There Are Two Basic Types of Cells: Prokaryotic and Eukaryotic 4.3 What Are the Major Features of Eukaryotic Cells? Some Eukaryotic Cells Are Supported by Cell Walls The Cytoskeleton Provides Shape, Support, and Movement Cilia and Flagella Move the Cell Through Fluid or Move Fluid Past the Cell The Nucleus Is the Control Center of the Eukaryotic Cell Eukaryotic Cytoplasm Includes an Elaborate System of Membranes Vacuoles Serve Many Functions, Including Water Regulation, Support, and Storage Mitochondria Extract Energy from Food Molecules, and Chloroplasts Capture Solar Energy Plants Use Plastids for Storage 4.4 What Are the Major Features of Prokaryotic Cells? Prokaryotic Cells Are Small and Possess Specialized Surface Features Links to Life: Unwanted Guests Prokaryotic Cells Have Fewer Specialized Structures Within Their Cytoplasm Case Study Revisited: Spare Parts for Human Bodies 5 Cell Membrane Structure and Function 000 Case Study: Vicious Venoms 5.1 How Is the Structure of a Membrane Related to Its Function? Cell Membranes Isolate the Cell Contents While Allowing Communication with the Environment Membranes Are "Fluid Mosaics" in Which Proteins Move Within Layers of Lipids The Phospholipid Bilayer Is the Fluid Portion of the Membrane A Mosaic of Proteins Is Embedded in the Membrane 5.2 How Do Substances Move Across Membranes? Molecules in Fluids Move in Response to Gradients Movement Across Membranes Occurs by Both Passive and Active Transport Passive Transport Includes Simple Diffusion, Facilitated Diffusion, and Osmosis Scientific Inquiry: The Discovery of Aquaporins Active Transport Uses Energy to Move Molecules Against Their Concentration Gradients Cells Engulf Particles or Fluids by Endocytosis Exocytosis Moves Material Out of the Cell Exchange of Materials Across Membranes Influences Cell Size and Shape 5.3 How Do Specialized Junctions Allow Cells to Connect and Communicate? Desmosomes Attach Cells Together Tight Junctions Make Cell Attachments Leakproof Gap Junctions and Plasmodesmata Allow Direct Communication Between Cells Evolutionary Connections: Caribou Legs and Membrane Diversity Case Study Revisited: Vicious Venoms 6 Energy Flow in the Life of a Cell 000 Case Study: Energy Unleashed 6.1 What Is Energy? The Laws of Thermodynamics Describe the Basic Properties of Energy Living Things Use the Energy of Sunlight to Create the Low-Entropy Conditions of Life 6.2 How Does Energy Flow in Chemical Reactions? Exergonic Reactions Release Energy Endergonic Reactions Require a Net Input of Energy Coupled Reactions Link Exergonic with Endergonic Reactions 6.3 How Is Cellular Energy Carried Between Coupled Reactions? ATP Is the Principal Energy Carrier in Cells Electron Carriers Also Transport Energy Within Cells 6.4 How Do Cells Control Their Metabolic Reactions? At Body Temperatures, Spontaneous Reactions Proceed Too Slowly to Sustain Life Catalysts Reduce Activation Energy Enzymes Are Biological Catalysts Cells Regulate Metabolism by Controlling Enzymes Poisons, Drugs, and Environmental Conditions Influence Enzyme Activity Case Study Revisited: Energy Unleashed Links to Life: Lack of an Enzyme Leads to Lactose Intolerance 7 Capturing Solar Energy: Photosynthesis 000 Case Study: Did the Dinosaurs Die from Lack of Sunlight? 7.1 What Is Photosynthesis? Leaves and Chloroplasts Are Adaptations for Photosynthesis Photosynthesis Consists of Light-Dependent and Light-Independent Reactions 7.2 Light-Dependent Reactions: How Is Light Energy Converted to Chemical Energy? During Photosynthesis, Light Is First Captured by Pigments in Chloroplasts The Light-Dependent Reactions Occur in Association with the Thylakoid Membranes A Closer Look: Chemiosmosis-ATP Synthesis in Chloroplasts 7.3 Light-Independent Reactions: How Is Chemical Energy Stored in Glucose Molecules? TheCycle Captures Carbon Dioxide Carbon Fixed During theCycle Is Used to Synthesize Glucose 7.4 What Is the Relationship Between Light-Dependent and Light-Independent Reactions? 7.5 Water,and thePathway When Stomata Are Closed to Conserve Water, Wasteful Photorespiration Occurs Plants Reduce Photorespiration by Means of a Two-Stage Carbon-Fixation Process andPlants Are Each Adapted to Different Environmental Conditions Case Study Revisited: Did the Dinosaurs Die from Lack of Sunlight? Links to Life: You Owe Your Life to Plants 8 Harvesting Energy: Glycolysis and Cellular Respiration 000 Case Study: When Athletes Boost Their Blood Counts: Do Cheaters Prosper? 8.1 How Do Cells Obtain Energy? Photosynthesis Is the Ultimate Source of Cellular Energy Glucose Is a Key Energy-Storage Molecule An Overview of Glucose Breakdown 8.2 How Is the Energy in Glucose Captured During Glycolysis? Glycolysis Breaks Down Glucose to Pyruvate, Releasing Chemical Energy A Closer Look: Glycolysis In the Absence of Oxygen, Fermentation Follows Glycolysis Links to Life: A Jug of Wine, a Loaf of Bread, and a Nice Bowl of Sauerkraut 8.3 How Does Cellular Respiration Capture Additional Energy from Glucose? Cellular Respiration in Eukaryotic Cells Occurs in Mitochondria Pyruvate Is Broken Down in the Mitochondrial Matrix, Releasing More Energy A Closer Look: The Mitochondrial Matrix Reactions High-Energy Electrons Travel Through the Electron Transport Chain Chemiosmosis Captures Energy Stored in a Hydrogen Ion Gradient and Produces ATP 8.4 Putting It All Together A Summary of Glucose Breakdown in Eukaryotic Cells Glycolysis and Cellular Respiration Influence the Way Organisms Function Health Watch: Why Can You Get Fat by Eating Sugar? Case Study Revisited: When Athletes Boost Their Blood Counts: Do Cheaters Prosper? UNIT TWO Inheritance 000 9 DNA: The Molecule of Heredity 000 Case Study: Muscles, Mutations, and Myostatin 9.1 How Did Scientists Discover That Genes Are Made of DNA? Transformed Bacteria Revealed the Link Between Genes and DNA Scientific Inquiry: DNA Is the Hereditary Molecule of Bacteriophages 9.2 What Is the Structure of DNA? DNA Is Composed of Four Nucleotides DNA Is a Double Helix of Two Nucleotide Strands Hydrogen Bonds Between Complementary Bases Hold the Two DNA Strands Together 9.3 How Does DNA Encode Information? Scientific Inquiry: The Discovery of the Double Helix 9.4 How Does DNA Replication Ensure Genetic Constancy During Cell Division? Replication of DNA Is a Critical Event in a Cell's Life DNA Replication Produces Two DNA Double Helices, Each with One Original Strand and One New Strand A Closer Look: DNA Structure and Replication 9.5 How Do Mutations Occur? Accurate Replication and Proofreading Produce Almost Error-Free DNA Mistakes Do Happen Mutations Range from Changes in Single Nucleotide Pairs to Movements of Large Pieces of Chromosomes Mutations May Have Varying Effects on Function Case Study Revisited: Muscles, Mutations, and Myostatin 10 Gene Expression and Regulation 000 Case Study: Vive la Diff¿rence! 10.1 How Are Genes and Proteins Related? Most Genes Contain the Information for the Synthesis of a Single Protein DNA Provides Instructions for Protein Synthesis via RNA Intermediaries Overview: Genetic Information Is Transcribed into RNA and Then Translated into Protein The Genetic Code Uses Three Bases to Specify an Amino Acid 10.2 How Is Information in a Gene Transcribed into RNA? Initiation of Transcription Occurs When RNA Polymerase Binds to the Promoter of a Gene Elongation Proceeds Until RNA Polymerase Reaches a Termination Signal 10.3 How Is the Base Sequence of a Messenger RNA Molecule Translated into Protein? Messenger RNA Carries the Code for Protein Synthesis from DNA to Ribosomes Ribosomes Consist of Two Subunits, Each Composed of Ribosomal RNA and Protein Transfer RNA Molecules Decode the Sequence of Bases in mRNA into the Amino Acid Sequence of a Protein During Translation, mRNA, tRNA, and Ribosomes Cooperate to Synthesize Proteins Links to Life: Genetics, Evolution, and Medicine A Closer Look at Protein Synthesis: A High-Energy Business Recap: Decoding the Sequence of Bases in DNA into the Sequence of Amino Acids in Protein Requires Transcription and Translation 10.4 How Do Mutations in DNA Affect the Function of Genes? Mutations May Have a Variety of Effects on Protein Structure and Function Mutations Provide the Raw Material for Evolution 10.5 How Are Genes Regulated? Gene Regulation in Prokaryotes Gene Regulation in Eukaryotes Scientific Inquiry: RNA: It's Not Just a Messenger Any More Eukaryotic Cells May Regulate the Transcription of Individual Genes, Regions of Chromosomes, or Entire Chromosomes Health Watch: Sex, Aging, and Mutations Case Study Revisited: Vive la Diff¿rence! 11 The Continuity of Life: Cellular Reproduction 000 Case Study: How Much Is a Great Tan Worth? 11.1 What Is the Role of Cellular Reproduction in the Lives of Individual Cells and Entire Organisms? The Prokaryotic Cell Cycle Consists of Growth and Binary Fission The Eukaryotic Cell Cycle Consists of Interphase and Cell Division 11.2 How Is DNA in Eukaryotic Cells Organized into Chromosomes? The Eukaryotic Chromosome Consists of a Linear DNA Double Helix Bound to Proteins Eukaryotic Chromosomes Usually Occur in Homologous Pairs with Similar Genetic Information 11.3 How Do Cells Reproduce by Mitotic Cell Division? During Prophase, the Chromosomes Condense and the Spindle Microtubules Form and Attach to the Chromosomes During Metaphase, the Chromosomes Align Along the Equator of the Cell During Anaphase, Sister Chromatids Separate and Are Pulled to Opposite Poles of the Cell During Telophase, Nuclear Envelopes Form Around Both Groups of Chromosomes During Cytokinesis, the Cytoplasm Is Divided Between Two Daughter Cells Scientific Inquiry: Carbon Copies-Cloning in Nature and the Lab 11.4 How Is the Cell Cycle Controlled? Checkpoints Regulate Progress Through the Cell Cycle Controls over the Checkpoints The Activities of Specific Enzymes Drive the Cell Cycle Health Watch: Cancer-Mitotic Cell Division Run Amok 11.5 Why Do So Many Organisms Reproduce Sexually? Mutations in DNA Are the Ultimate Source of Genetic Variability Sexual Reproduction May Combine Different Parental Alleles in a Single Offspring 11.6 How Does Meiotic Cell Division Produce Haploid Cells? Meiosis Separates Homologous Chromosomes, Producing Haploid Daughter Nuclei Meiotic Cell Division Followed by Fusion of Gametes Keeps the Chromosome Number Constant from Generation to Generation Meiosis I Separates Homologous Chromosomes into Two Haploid Daughter Nuclei Meiosis II Separates Sister Chromatids into Four Daughter Nuclei 11.7 When Do Mitotic and Meiotic Cell Division Occur in the Life Cycles of Eukaryotes? In Haploid Life Cycles, the Majority of the Cycle Consists of Haploid Cells In Diploid Life Cycles, the Majority of the Cycle Consists of Diploid Cells In Alternation-of-Generation Life Cycles, There Are Both Diploid and Haploid Multicellular Stages 11.8 How Do Meiosis and Sexual Reproduction Produce Genetic Variability? Shuffling of Homologues Creates Novel Combinations of Chromosomes Crossing Over Creates Chromosomes with Novel Combinations of Genes Fusion of Gametes Adds Further Genetic Variability to the Offspring Case Study Revisited: How Much Is a Great Tan Worth? 12 Patterns of Inheritance 000 Case Study: Sudden Death on the Court 12.1 What Is the Physical Basis of Inheritance? Genes Are Sequences of Nucleotides at Specific Locations on Chromosomes An Organism's Two Alleles May Be the Same or Different 12.2 How Did Gregor Mendel Lay the Foundations for Modern Genetics? Doing It Right: The Secrets of Mendel's Success 12.3 How Are Single Traits Inherited? The Inheritance of Dominant and Recessive Alleles on Homologous Chromosomes Can Explain the Results of Mendel's Crosses Simple "Genetic Bookkeeping" Can Predict Genotypes and Phenotypes of Offspring Mendel's Hypothesis Can Be Used to Predict the Outcome of New Types of Single-Trait Crosses 12.4 How Are Multiple Traits Inherited? Mendel Hypothesized That Traits Are Inherited Independently In an Unprepared World, Genius May Go Unrecognized 12.5 How Are Genes Located on the Same Chromosome Inherited? Genes on the Same Chromosome Tend to Be Inherited Together Recombination Can Create New Combinations of Linked Alleles 12.6 How Is Sex Determined, and How Are Sex-Linked Genes Inherited? Sex-Linked Genes Are Found Only on the X or Only on the Y Chromosome 12.7 Do the Mendelian Rules of Inheritance Apply to All Traits? Incomplete Dominance: The Phenotype of Heterozygotes Is Intermediate Between the Phenotypes of the Homozygotes A Single Gene May Have Multiple Alleles Scientific Inquiry: Cystic Fibrosis Many Traits Are Influenced by Several Genes Single Genes Typically Have Multiple Effects on Phenotype The Environment Influences the Expression of Genes 12.8 How Are Human Genetic Disorders Investigated? 12.9 How Are Human Disorders Caused by Single Genes Inherited? Some Human Genetic Disorders Are Caused by Recessive Alleles Some Human Genetic Disorders Are Caused by Dominant Alleles Some Human Genetic Disorders Are Sex-Linked 12.10 How Do Errors in Chromosome Number Affect Humans? Some Genetic Disorders Are Caused by Abnormal Numbers of Sex Chromosomes Some Genetic Disorders Are Caused by Abnormal Numbers of Autosomes Case Study Revisited: Sudden Death on the Court 13 Biotechnology 000 Case Study: Guilty or Innocent? 13.1 What Is Biotechnology? 13.2 How Does DNA Recombine in Nature? Sexual Reproduction Recombines DNA Transformation May Combine DNA from Different Bacterial Species Viruses May Transfer DNA Between Species 13.3 How Is Biotechnology Used in Forensic Science? The Polymerase Chain Reaction Amplifies DNA Scientific Inquiry: Hot Springs and Hot Science Gel Electrophoresis Separates DNA Segments DNA Probes Are Used to Label Specific Nucleotide Sequences Every Person Has a Unique DNA Profile 13.4 How Is Biotechnology Used in Agriculture? Many Crops Are Genetically Modified Genetically Modified Plants May Be Used to Produce Medicines Genetically Modified Animals May Be Useful in Agriculture and Medicine 13.5 How Is Biotechnology Used to Learn About the Human Genome? 13.6 How Is Biotechnology Used for Medical Diagnosis and Treatment? DNA Technology Can Be Used to Diagnose Inherited Disorders DNA Technology Can Help to Treat Disease 13.7 What Are the Major Ethical Issues of Modern Biotechnology? Links to Life: Biotechnology-from the Sublime to the Ridiculous Should Genetically Modified Organisms Be Permitted in Agriculture? Biotechnology Watch: Golden Rice Should the Genome of Humans Be Changed by Biotechnology? Health Watch: Prenatal Genetic Screening Case Study Revisited: Guilty or Innocent? UNIT THREE Evolution and Diversity of Life 000 14 Principles of Evolution 000 Case Study: What Good Are Wisdom Teeth? 14.1 How Did Evolutionary Thought Evolve? Early Biological Thought Did Not Include the Concept of Evolution Exploration of New Lands Revealed a Staggering Diversity of Life A Few Scientists Speculated That Life Had Evolved Fossil Discoveries Showed That Life Has Changed over Time Some Scientists Devised Nonevolutionary Explanations for Fossils Geology Provided Evidence That Earth Is Exceedingly Old Some Pre-Darwin Biologists Proposed Mechanisms for Evolution Darwin and Wallace Proposed a Mechanism of Evolution Scientific Inquiry: Charles Darwin-Nature Was His Laboratory 14.2 How Do We Know That Evolution Has Occurred? Fossils Provide Evidence of Evolutionary Change over Time Comparative Anatomy Gives Evidence of Descent with Modification Embryological Similarity Suggests Common Ancestry Modern Biochemical and Genetic Analyses Reveal Relatedness Among Diverse Organisms 14.3 How Does Natural Selection Work? Darwin and Wallace's Theory Rests on Four Postulates Postulate 1: Populations Vary Postulate 2: Traits Are Inherited Postulate 3: Some Individuals Fail to Survive and Reproduce Postulate 4: Reproductive Success Is Not Random Natural Selection Modifies Populations over Time 14.4 What Is the Evidence That Populations Evolve by Natural Selection? Controlled Breeding Modifies Organisms Evolution by Natural Selection Occurs Today 14.5 A Postscript by Charles Darwin Case Study Revisited: What Good Are Wisdom Teeth? 15 How Organisms Evolve 000 Case Study: Evolution of a Menace 15.1 How Are Populations, Genes, and Evolution Related? Genes and the Environment Interact to Determine Traits The Gene Pool Is the Sum of the Genes in a Population Evolution Is the Change of Allele Frequencies Within a Population The Equilibrium Population Is a Hypothetical Population in Which Evolution Does Not Occur A Closer Look: The Hardy-Weinberg Principle 15.2 What Causes Evolution? Mutations Are the Original Source of Genetic Variability Gene Flow Between Populations Changes Allele Frequencies Allele Frequencies May Drift in Small Populations Mating Within a Population Is Almost Never Random All Genotypes Are Not Equally Beneficial Earth Watch: Endangered Species-From Gene Pools to Gene Puddles 15.3 How Does Natural Selection Work? Natural Selection Stems from Unequal Reproduction Natural Selection Acts on Phenotypes Some Phenotypes Reproduce More Successfully Than Others Selection Can Influence Populations in Three Ways Case Study Revisited: Evolution of a Menace 16 The Origin of Species 000 Case Study: Lost World 16.1 What Is a Species? Biologists Need a Clear Definition of Species Species Are Groups of Interbreeding Populations Appearance Can Be Misleading 16.2 How Is Reproductive Isolation Between Species Maintained? Premating Isolating Mechanisms Prevent Mating Between Species Postmating Isolating Mechanisms Limit Hybrid Offspring 16.3 How Do New Species Form? Geographic Separation of a Population Can Lead to Allopatric Speciation Ecological Isolation of a Population Can Lead to Sympatric Speciation Under Some Conditions, Many New Species May Arise A Closer Look: Speciation by Mutation 16.4 What Causes Extinction? Localized Distribution and Overspecialization Make Species Vulnerable in Changing Environments Interactions with Other Organisms May Drive a Species to Extinction Habitat Change and Destruction Are the Leading Causes of Extinction Earth Watch: Hybridization and Extinction Evolutionary Connections: Scientists Don't Doubt Evolution Case Study Revisited: Lost World Links to Life: Biological Vanity Plates 17 The History of Life 000 Case Study: Little People, Big Story 17.1 How Did Life Begin? Experiments Refuted Spontaneous Generation The First Living Things Arose from Nonliving Ones RNA May Have Been the First Self-Reproducing Molecule Membrane-Like Vesicles May Have Enclosed Ribozymes But Did All This Happen? 17.2 What Were the Earliest Organisms Like? The First Organisms Were Anaerobic Prokaryotes Some Organisms Evolved the Ability to Capture the Sun's Energy Photosynthesis Increased the Amount of Oxygen in the Atmosphere Scientific Inquiry: How Do We Know How Old a Fossil Is? Aerobic Metabolism Arose in Response to the Oxygen Crisis Some Organisms Acquired Membrane-Enclosed Organelles 17.3 What Were the Earliest Multicellular Organisms Like? Some Algae Became Multicellular Animal Diversity Arose in the Precambrian Era 17.4 How Did Life Invade the Land? Some Plants Became Adapted to Life on Dry Land Some Animals Became Adapted to Life on Dry Land 17.5 What Role Has Extinction Played in the History of Life? Evolutionary History Has Been Marked by Periodic Mass Extinctions Climate Change Contributed to Mass Extinctions Catastrophic Events May Have Caused the Worst Mass Extinctions 17.6 How Did Humans Evolve? Humans Inherited Some Early Primate Adaptations for Life in Trees The Oldest Hominid Fossils Are from Africa The Earliest Hominids Could Stand and Walk Upright Several Species of Australopithecus Emerged in Africa The Genus Homo Diverged from the Australopithecines 2.5 Million Years Ago The Evolution of Homo Was Accompanied by Advances in Tool Technology Neanderthals Had Large Brains and Excellent Tools Modern Humans Emerged Less than 200,000 Years Ago Several Waves of Hominids Emigrated from Africa The Evolutionary Origin of Large Brains May Be Related to Meat Consumption The Evolutionary Origin of Human Behavior Is Highly Speculative The Cultural Evolution of Humans Now Far Outpaces Biological Evolution Case Study Revisited: Little People, Big Story 18 Systematics: Seeking Order Amidst Diversity 000 Case Study: Origin of a Killer 18.1 How Are Organisms Named and Classified? Each Species Has a Unique, Two-Part Name Classification Originated as a Hierarchy of Categories Systematists Identify Features That Reveal Evolutionary Relationships Anatomy Plays a Key Role in Systematics Molecular Similarities Are Also Useful for Reconstructing Phylogeny Scientific Inquiry: Molecular Genetics Reveals Evolutionary Relationships A Closer Look: Reconstructing Phylogenetic Trees 18.2 What Are the Domains of Life? The Five-Kingdom System Improved Classification A Three-Domain System More Accurately Reflects Life's History Kingdom-Level Classification Remains Unsettled 18.3 Why Do Classifications Change? Species Designations Change When New Information Is Discovered The Biological Species Definition Can Be Difficult or Impossible to Apply 18.4 How Many Species Exist? Case Study Revisited: Origin of a Killer Links to Life: Small World 19 The Diversity of Prokaryotes and Viruses 000 Case Study: Agents of Death 19.1 Which Organisms Make Up the Prokaryotic Domains-Bacteria and Archaea? Bacteria and Archaea Are Fundamentally Different Classification of Prokaryotes Within Each Domain Is Difficult Prokaryotes Differ in Size and Shape 19.2 How Do Prokaryotes Survive and Reproduce? Some Prokaryotes Are Mobile Many Bacteria Form Films on Surfaces Protective Endospores Allow Some Bacteria to Withstand Adverse Conditions Prokaryotes Are Specialized for Specific Habitats Prokaryotes Exhibit Diverse Metabolisms Prokaryotes Reproduce by Binary Fission Prokaryotes May Exchange Genetic Material Without Reproducing 19.3 How Do Prokaryotes Affect Humans and Other Eukaryotes? Prokaryotes Play Important Roles in Animal Nutrition Prokaryotes Capture the Nitrogen Needed by Plants Prokaryotes Are Nature's Recyclers Prokaryotes Can Clean Up Pollution Some Bacteria Pose a Threat to Human Health Links to Life: Unwelcome Dinner Guests 19.4 What Are Viruses, Viroids, and Prions? A Virus Consists of a Molecule of DNA or RNA Surrounded by a Protein Coat A Closer Look: Viruses-How the Nonliving Replicate Some Infectious Agents Are Even Simpler Than Viruses No One Is Certain How These Infectious Particles Originated Case Study Revisited: Agents of Death 20 The Diversity of Protists 000 Case Study: Green Monster 20.1 What Are Protists? Most Protists Are Single-Celled Protists Use Diverse Modes of Nutrition Protists Use Diverse Modes of Reproduction Protists Have Significant Effects on Humans 20.2 What Are the Major Groups of Protists? Excavates Lack Mitochondria Euglenozoans Have Distinctive Mitochondria Stramenopiles Include Photosynthetic and Non-Photosynthetic Organisms Alveolates Include Parasites, Predators, and Phytoplankton Cercozoans Have Thin Pseudopods and Elaborate Shells Amoebozoans Inhabit Aquatic and Terrestrial Environments Red Algae Live Primarily in Clear Tropical Oceans Green Algae Live Mostly in Ponds and Lakes Evolutionary Connections: Our Unicellular Ancestors Case Study Revisited: Green Monster 21 The Diversity of Plants 000 Case Study: Queen of the Parasites 21.1 What Are the Key Features of Plants? Plants Have Alternating Multicellular Haploid and Diploid Generations Plants Have Multicellular, Dependent Embryos Plants Play a Crucial Ecological Role Plants Provide Humans with Necessities and Luxuries Plants Are Adapted to Life on Land 21.2 What Is the Evolutionary Origin of Plants? Green Algae Gave Rise to Plants The Ancestors of Plants Lived in Fresh Water 21.3 How Have Plants Adapted to Life on Land? Plant Bodies Resist Gravity and Drying Plant Embryos Are Protected, and Plant Sex Cells May Disperse Without Water 21.4 What Are the Major Groups of Plants? Bryophytes Lack Conducting Structures Vascular Plants Have Conducting Vessels That Also Provide Support The Seedless Vascular Plants Include the Club Mosses, Horsetails, and Ferns The Seed Plants Dominate the Land, Aided by Two Important Adaptations: Pollen and Seeds Gymnosperms Are Nonflowering Seed Plants Angiosperms Are Flowering Seed Plants More Recently Evolved Plants Have Smaller Gametophytes Case Study Revisited: Queen of the Parasites 22 The Diversity of Fungi 000 Case Study: Humongous Fungus 22.1 What Are the Key Features of Fungi? Fungal Bodies Consist of Slender Threads Fungi Obtain Their Nutrients from Other Organisms Fungi Propagate by Spores Most Fungi Can Reproduce Both Sexually and Asexually 22.2 What Are the Major Groups of Fungi? Chytrids Produce Swimming Spores Zygomycetes Can Reproduce by Forming Diploid Spores Ascomycetes Form Spores in a Saclike Case Basidiomycetes Produce Club-Shaped Reproductive Structures 22.3 How Do Fungi Interact with Other Species? Lichens Are Formed by Fungi That Live with Photosynthetic Algae or Bacteria Mycorrhizae Are Fungi Associated with Plant Roots Endophytes Are Fungi That Live Inside Plant Stems and Leaves Some Fungi Are Important Recyclers 22.4 How Do Fungi Affect Humans? Fungi Attack Plants That Are Important to People Fungi Cause Human Diseases Fungi Can Produce Toxins Many Antibiotics Are Derived from Fungi Fungi Make Important Contributions to Gastronomy Earth Watch: The Case of the Disappearing Mushrooms Evolutionary Connections: Fungal Ingenuity-Pigs, Shotguns, and Nooses Case Study Revisited: Humongous Fungus Links to Life: Collect Carefully 23 Animal Diversity I: Invertebrates 000 Case Study: The Search for a Sea Monster 23.1 What Are the Key Features of Animals? 23.2 Which Anatomical Features Mark Branch Points on the Animal Evolutionary Tree? Lack of Tissues Separates Sponges from All Other Animals Animals with Tissues Exhibit Either Radial or Bilateral Symmetry Most Bilateral Animals Have Body Cavities Bilateral Organisms Develop in One of Two Ways Protostomes Include Two Distinct Evolutionary Lines 23.3 What Are the Major Animal Phyla? Sponges Have a Simple Body Plan Cnidarians Are Well-Armed Predators Flatworms Have Organs but Lack Respiratory and Circulatory Systems Annelids Are Composed of Identical Segments Links to Life: Physicians' Assistants Most Mollusks Have Shells Arthropods Are the Dominant Animals on Earth Roundworms Are Abundant and Mostly Tiny Echinoderms Have a Calcium Carbonate Skeleton The Chordates Include the Vertebrates Case Study Revisited: The Search for a Sea Monster 24 Animal Diversity II: Vertebrates 000 Case Study: Fish Story 24.1 What Are the Key Features of Chordates? All Chordates Share Four Distinctive Features The Invertebrate Chordates Live in the Seas Invertebrate Chordates Lack a Backbone Vertebrates Have a Backbone 24.2 What Are the Major Groups of Vertebrates? Some Vertebrates Lack Jaws Jawed Fishes Rule Earth's Waters Earth Watch: Frogs in Peril Amphibians Live a Double Life Reptiles and Birds Are Adapted for Life on Land Mammals Provide Milk to Their Offspring Evolutionary Connections: Are Humans a Biological Success? Case Study Revisited: Fish Story Links to Life: Do Animals Belong in Laboratories? UNIT FOUR Behavior and Ecology 000 25 Animal Behavior 000 Case Study: Sex and Symmetry 25.1 How Do Innate and Learned Behaviors Differ? Innate Behaviors Can Be Performed Without Prior Experience Learned Behaviors Are Modified by Experience Evolutionary Connections: Why Do Animals Play? There Is No Sharp Distinction Between Innate and Learned Behaviors 25.2 How Do Animals Communicate? Visual Communication Is Most Effective over Short Distances Communication by Sound Is Effective over Longer Distances Chemical Messages Persist Longer but Are Hard to Vary Communication by Touch Helps Establish Social Bonds 25.3 How Do Animals Compete for Resources? Aggressive Behavior Helps Secure Resources Dominance Hierarchies Help Manage Aggressive Interactions Animals May Defend Territories That Contain Resources 25.4 How Do Animals Find Mates? Signals Encode Sex, Species, and Individual Quality 25.5 What Kinds of Societies Do Animals Form? Group Living Has Advantages and Disadvantages The Extent of Sociality Varies Among Species Forming Groups with Relatives Fosters the Evolution of Altruism Honeybees Live Together in Rigidly Structured Societies Naked Mole Rats Form a Complex Vertebrate Society 25.6 Can Biology Explain Human Behavior? The Behavior of Newborn Infants Has a Large Innate Component Young Humans Acquire Language Easily Behaviors Shared by Diverse Cultures May Be Innate Humans May Respond to Pheromones Studies of Twins Reveal Genetic Components of Behavior Biological Investigation of Human Behavior Is Controversial Case Study Revisited: Sex and Symmetry 26 Population Growth and Regulation 000 Case Study: The Mystery of Easter Island 26.1 How Does Population Size Change? Biotic Potential Can Produce Exponential Growth 26.2 How Is Population Growth Regulated? Exponential Growth Occurs Only Under Special Conditions Environmental Resistance Limits Population Growth 26.3 How Are Populations Distributed in Space and Time? Populations Exhibit Different Spatial Distributions Survivorship in Populations Follows Three Basic Patterns 26.4 How Is the Human Population Changing? Demographers Track Changes in Human Populations The Human Population Continues to Grow Rapidly Earth Watch: Have We Exceeded Earth's Carrying Capacity? Technological Advances Have Increased Earth's Capacity to Support People The Demographic Transition Helps Stabilize Populations Population Growth Is Unevenly Distributed The Current Age Structure of a Population Predicts Its Future Growth Fertility in Europe Is Below Replacement Level The U.S. Population Is Growing Rapidly Links to Life: Treading Lightly-How Big Is Your "Footprint"? Case Study Revisited: The Mystery of Easter Island 27 Community Interactions 000 Case Study: Invasion of the Zebra Mussels 27.1 Why Are Community Interactions Important? 27.2 What Is the Relationship Between Ecological Niche and Competition? The Ecological Niche Defines the Place and Role of Each Species in Its Ecosystem Competition Occurs Whenever Two Organisms Attempt to Use the Same, Limited Resources Adaptations Reduce the Overlap of Ecological Niches Among Coexisting Species Interspecific Competition May Reduce the Population Size and Distribution of Each Species Competition Within a Species Is a Major Factor Controlling Population Size 27.3 What Are the Results of Interactions Between Predators and Their Prey? Predator-Prey Interactions Shape Evolutionary Adaptations Earth Watch: Invasive Species Disrupt Community Interactions 27.4 What Is Symbiosis? Parasitism Harms, but Does Not Immediately Kill, the Host In Mutualistic Interactions, Both Species Benefit Scientific Inquiry: Ants and Acacias-An Advantageous Association 27.5 How Do Keystone Species Influence Community Structure? 27.6 Succession: How Do Community Interactions Cause Change over Time? There Are Two Major Forms of Succession: Primary and Secondary Succession Also Occurs in Ponds and Lakes Succession Culminates in the Climax Community Some Ecosystems Are Maintained in a Subclimax State Evolutionary Connections: Is Camouflage Splitting a Species? Case Study Revisited: Invasion of the Zebra Mussels 28 How Do Ecosystems Work? 000 Case Study: When the Salmon Return 28.1 What Are the Pathways of Energy and Nutrients? 28.2 How Does Energy Flow Through Communities? Energy Enters Communities Through Photosynthesis Energy Is Passed from One Trophic Level to Another Energy Transfer Through Trophic Levels Is Inefficient Earth Watch: Food Chains Magnify Toxic Substances 28.3 How Do Nutrients Move Within and Among Ecosystems? Carbon Cycles Through the Atmosphere, Oceans, and Communities The Major Reservoir for Nitrogen Is the Atmosphere The Phosphorus Cycle Has No Atmospheric Component Most Water Remains Chemically Unchanged During the Hydrologic Cycle 28.4 What Causes "Acid Rain"? Overloading the Nitrogen and Sulfur Cycles Causes Acid Deposition Acid Deposition Damages Life in Lakes and Forests The Clean Air Act Has Significantly Reduced Sulfur, but Not Nitrogen, Emissions 28.5 What Causes Global Warming? Interfering with the Carbon Cycle Contributes to Global Warming Greenhouse Gases Trap Heat in the Atmosphere Global Warming Will Have Severe Consequences Earth Watch: Poles in Peril How Are People Responding to the Threat? Links to Life: Making a Difference Case Study Revisited: When the Salmon Return 29 Earth's Diverse Ecosystems 000 Case Study: Wings of Hope 29.1 What Factors Influence Earth's Climate? Both Climate and Weather Are Driven by the Sun Earth's Physical Features Also Influence Climate Earth Watch: The Ozone Hole-A Puncture in Our Protective Shield 29.2 What Conditions Does Life Require? 29.3 How Is Life on Land Distributed? Terrestrial Biomes Support Characteristic Plant Communities Links to Life: Crave Chocolate and Save Rain Forests? Rainfall and Temperature Limit the Plant Life of a Biome 29.4 How Is Life in Water Distributed? Freshwater Ecosystems Include Lakes, Streams, and Rivers Marine Ecosystems Cover Much of Earth Case Study Revisited: Wings of Hope 30 Conserving Life on Earth 000 Case Study: Back from Extinction 30.1 What Is Biodiversity, and Why Should We Care About It? Ecosystem Services: Practical Uses for Biodiversity Ecological Economics Recognizes the Monetary Value of Ecosystem Services Earth Watch: Restoring the Everglades 30.2 Is Earth's Biodiversity Diminishing? Extinction Is a Natural Process, but Rates Have Risen Dramatically Increasing Numbers of Species Are Threatened with Extinction 30.3 What Are The Major Threats to Biodiversity? Humanity Is Depleting Earth's "Ecological Capital" Human Activities Threaten Biodiversity in Four Major Ways Earth Watch: Tangled Troubles-Logging, Fishing, and Bushmeat Earth Watch: Saving Sea Turtles 30.4 How Can Conservation Biology Help to Preserve Biodiversity? The Foundations of Conservation Biology Conservation Biology Is an Integrated Science Conserving Wild Ecosystems Earth Watch: Restoring a Keystone Predator 30.5 Why Is Sustainability the Key to Conservation? Sustainable Living and Sustainable Development Promote Long-Term Ecological and Human Well-Being Biosphere Reserves Provide Models for Conservation and Sustainable Development Sustainable Agriculture Helps Preserve Natural Communities Earth Watch: Preserving Biodiversity with Shade-Grown Coffee The Future Is in Your Hands Links to Life: What Can Individuals Do? Case Study Revisited: Back from Extinction UNIT FIVE Animal Anatomy and Physiology 000 31 Homeostasis and the Organization of the Animal Body 000 Case Study: Life on Hold? 000 31.1 Homeostasis: How Do Animals Maintain Internal Constancy? 000 The Internal Environment Is Maintained in a State of Dynamic Constancy 000 Animals May Be Categorized by How They Regulate Body Temperature 000 Links to Life: Heat or Humidity? 000 Feedback Systems Regulate Internal Conditions 000 The Body's Internal Systems Act in Concert 000 31.2 How Is the Animal Body Organized? 000 Animal Tissues Are Composed of Similar Cells That Perform a Specific Function 000 Organs Include Two or More Interacting Tissue Types 000 Organ Systems Consist of Two or More Interacting Organs 000 Case Study Revisited: Life on Hold? 000 32 Circulation 000 Case Study: Sudden Death 000 32.1 What Are the Major Features and Functions of Circulatory Systems? 000 Animals Have Two Types of Circulatory Systems 000 The Vertebrate Circulatory System Has Diverse Functions 000 32.2 How Does the Vertebrate Heart Work? 000 Increasingly Complex and Efficient Hearts Have Arisen During Vertebrate Evolution 000 The Vertebrate Heart Consists of Muscular Chambers That Form Two Separate Pumps 000 Health Watch: Repairing Broken Hearts 000 32.3 What Is Blood? 000 Plasma Is Primarily Water in Which Proteins, Salts, Nutrients, and Wastes Are Dissolved 000 Red Blood Cells Carry Oxygen from the Lungs to the Tissues 000 Scientific Inquiry: Artificial Blood? Artificial Vessels? Artificial Hearts? 000 White Blood Cells Help Defend the Body Against Disease 000 Platelets Are Cell Fragments That Aid in Blood Clotting 000 32.4 What Are the Types and Functions of Blood Vessels? 000 Arteries and Arterioles Are Thick-Walled Vessels That Carry Blood Away from the Heart 000 Capillaries Are Microscopic Vessels That Allow the Blood and Body Cells to Exchange Nutrients and Wastes 000 Veins and Venules Carry Blood Back to the Heart 000 Arterioles Control the Distribution of Blood Flow 000 32.5 How Does the Lymphatic System Work with the Circulatory System? 000 Lymphatic Vessels Resemble the Veins and Capillaries of the Circulatory System 000 The Lymphatic System Returns Fluids to the Blood 000 The Lymphatic System Transports Fats from the Small Intestine to the Blood 000 The Lymphatic System Helps Defend the Body Against Disease 000 Case Study Revisited: Sudden Death 000 33 Respiration 000 Case Study: Lives Up in Smoke 000 33.1 Why Exchange Gases? 000 33.2 What Are Some Evolutionary Adaptations for Gas Exchange? 000 Some Animals in Moist Environments Lack Specialized Respiratory Structures 000 Respiratory Systems Facilitate Gas Exchange by Diffusion 000 Gills Facilitate Gas Exchange in Aquatic Environments 000 A Closer Look: Gills and Gases-Countercurrent Exchange 000 Terrestrial Animals Have Internal Respiratory Structures 000 33.3 How Does the Human Respiratory System Work? 000 The Conducting Portion of the Respiratory System Carries Air to the Lungs 000 Health Watch: Smoking-A Life and Breath Decision 000 Gas Exchange Occurs in the Alveoli 000 Oxygen and Carbon Dioxide Are Transported Using Different Mechanisms 000 Air Is Inhaled Actively and Exhaled Passively 000 Breathing Rate Is Controlled by the Respiratory Center of the Brain 000 Case Study Revisited: Lives Up in Smoke 000 Links to Life: Quitters Are Winners 000 34 Nutrition and Digestion 000 Case Study: Dieting to Death? 000 34.1 What Nutrients Do Animals Need? 000 Energy Is Derived from Nutrients and Measured in Calories 000 Lipids Include Fats, Phospholipids, and Cholesterol 000 Health Watch: Dying for a Cheesburger 000 Carbohydrates Are a Source of Quick Energy 000 Amino Acids Form the Building Blocks of Proteins 000 Minerals Are Elements Required by the Body 000 Vitamins Play Many Roles in Metabolism 000 The Human Body Is About Two-Thirds Water 000 Nutritional Guidelines Help People Obtain a Balanced Diet 000 34.2 How Is Digestion Accomplished? 000 An Overview of Digestion 000 In Sponges, Digestion Occurs Within Single Cells 000 A Sac with One Opening Forms the Simplest Digestive System 000 Digestion in a Tube Allows Animals to Feed More Frequently 000 Digestive Specializations 000 34.3 How Do Humans Digest Food? 000 Mechanical and Chemical Breakdown of Food Begins in the Mouth 000 The Esophagus Conducts Food to the Stomach 000 Most Digestion Occurs in the Small Intestine 000 Health Watch: Ulcers-Digesting the Digestive Tract 000 Most Absorption Occurs in the Small Intestine 000 Water Is Absorbed and Feces Are Formed in the Large Intestine 000 Digestion Is Controlled by the Nervous System and Hormones 000 Case Study Revisited: Dieting to Death? 000 35 The Urinary System 000 Case Study: A Perfect Match 000 35.1 What Are the Basic Functions of Urinary Systems? 000 35.2 What Are Some Examples of Invertebrate Excretory Systems? 000 Flame Cells Filter Fluids in Flatworms 000 Malphigian Tubules Filter the Blood of Insects 000 Nephridia Filter Fluid in Earthworms 000 35.3 What Are the Functions of Vertebrate Urinary Systems? 000 Vertebrate Kidneys Filter the Blood 000 Excretion of Nitrogenous Wastes Is Adapted to the Environment 000 35.4 What Are the Structures and Functions of the Human Urinary System? 000 The Urinary System Consists of the Kidneys, Ureters, Bladder, and Urethra 000 Urine Is Formed in the Nephrons of the Kidneys 000 A Closer Look: The Nephron and Urine Formation 000 Health Watch: When the Kidneys Collapse 000 35.5 How Do Mammalian Kidneys Help Maintain Homeostasis? 000 The Kidneys Regulate the Water Content of the Blood 000 Kidneys Release Hormones That Help Regulate Blood Pressure and Oxygen Levels 000 Kidneys Monitor and Regulate Dissolved Substances in the Blood 000 Vertebrate Kidneys Are Adapted to Diverse Environments 000 Case Study Revisited: A Perfect Match 000 Links to Life: Too Much to Drink? 000 36 Immunity: Defenses Against Disease 000 Case Study: Fighting the Flu 000 36.1 What Are the Basic Mechanisms of Defense Against Disease? 000 Vertebrate Animals Have Three Major Lines of Defense 000 Invertebrate Animals Possess the First Two Lines of Defense 000 36.2 How Do Nonspecific Defenses Function? 000 Skin and Mucous Membranes Form External Barriers to Invasion 000 Nonspecific Internal Defenses Combat Disease 000 36.3 What Are the Key Characteristics of the Immune Response? 000 Cells of the Immune System Recognize the Invader 000 Cells of the Immune System Launch an Attack 000 Cells of the Immune System Remember Past Victories 000 36.4 How Does Medical Care Augment the Immune Response? 000 Vaccinations Stimulate the Development of Memory Cells 000 Scientific Inquiry: The Discovery of Vaccines 000 Antibiotics Slow Down Microbial Reproduction 000 Health Watch: Fighting Influenza-Is a Bird Flu Pandemic Imminent? 000 36.5 What Happens When the Immune System Malfunctions? 000 Allergies Are Misdirected Immune Responses 000 An Autoimmune Disease Is an Immune Response Against the Body's Own Molecules 000 An Immune Deficiency Disease Disables the Immune System 000 Cancer Can Evade or Overwhelm the Immune Response 000 Case Study Revisited: Fighting the Flu 000 37 Chemical Control of the Animal Body: The Endocrine System 000 Case Study: Losing on Artificial Hormones 000 37.1 How Do Animal Cells Communicate? 000 37.2 What Are the Characteristics of Animal Hormones? 000 Local Hormones Diffuse to Nearby Target Cells 000 Hormones of the Endocrine System Are Transported by the Circulatory System 000 Hormones Bind to Specific Receptors on Target Cells 000 Hormone Release Is Regulated by Feedback Mechanisms 000 Vertebrate and Invertebrate Endocrine Hormones Show Striking Similarities 000 37.3 What Are the Structures and Hormones of the Mammalian Endocrine System? 000 Mammals Have Both Exocrine and Endocrine Glands 000 The Hypothalamus Controls Secretions of the Pituitary Gland 000 The Thyroid and Parathyroid Glands Influence Metabolism and Calcium Levels 000 Evolutionary Connections: The Evolution of Hormones 000 The Pancreas Is Both an Exocrine and an Endocrine Gland 000 The Sex Organs Secrete Steroid Hormones 000 Earth Watch: Endocrine Deception 000 The Adrenal Glands Have Two Parts That Secrete Different Hormones 000 Hormones Are Produced by the Pineal Gland, Thymus, Kidneys, Heart, Digestive Tract, and Fat Cells 000 Case Study Revisited: Losing on Artificial Hormones 000 Links to Life: Closer to a Cure for Diabetes 000 38 The Nervous System and the Senses 000 Case Study: How Do I Love Thee? 000 38.1 What Are the Structures and Functions of Neurons? 000 38.2 How Is Neural Activity Produced and Transmitted? 000 Neurons Produce Electrical Voltages Across Their Membranes 000 A Closer Look: Ions and Electrical Signaling in Neurons 000 Neurons Communicate at Synapses 000 Health Watch: Drugs, Diseases, and Neurotransmitters 000 38.3 How Are Nervous Systems Organized? 000 Information Processing in the Nervous System Requires Four Basic Operations 000 Neural Pathways Direct Behavior 000 Complex Nervous Systems Are Centralized 000 38.4 What Is the Structure of the Human Nervous System? 000 The Peripheral Nervous System Links the Central Nervous System to the Body 000 The Central Nervous System Consists of the Spinal Cord and Brain 000 The Spinal Cord Is a Cable of Axons Protected by the Backbone 000 The Brain Consists of Many Parts Specialized for Specific Functions 000 38.5 How Does the Brain Produce the Mind? 000 The "Left Brain" and "Right Brain" Are Specialized for Different Functions 000 Scientific Inquiry: Neuroimaging-Peering into the "Black Box" 000 The Mechanisms of Learning and Memory Are Subjects of Intensive Research 000 Insights About How the Brain Creates the Mind Come from Diverse Sources 000 38.6 How Do Sensory Receptors Work? 000 38.7 How Are Mechanical Stimuli Detected? 000 38.8 How Is Sound Sensed? 000 The Ear Converts Sound Waves into Electrical Signals 000 38.9 How Is Light Sensed? 000 The Compound Eyes of Arthropods Produce a Mosaic Image 000 The Mammalian Eye Collects and Focuses Light, Converting It into Electrical Signals 000 38.10 How Are Chemicals Sensed? 000 Olfactory Receptors Detect Airborne Chemicals 000 Taste Receptors Detect Chemicals That Contact the Tongue 000 Pain Is a Specialized Chemical Sense 000 Evolutionary Connections: Uncommon Senses 000 Case Study Revisited: How Do I Love Thee? 000 39 Action and Support: The Muscles and Skeleton 000 Case Study: Hidden Hazards of Space Travel 000 39.1 An Introduction to the Muscular and Skeletal Systems 000 39.2 How Do Muscles Work? 000 Skeletal Muscle Cell Structure and Function Are Closely Linked 000 Muscle Contraction Results from Thick and Thin Filaments Sliding Past One Another 000 Cardiac Muscle Powers the Heart 000 Smooth Muscle Produces Slow, Involuntary Contractions 000 39.3 What Does the Skeleton Do? 000 Three Types of Skeletons Are Found in Animals 000 The Vertebrate Skeleton Serves Many Functions 000 39.4 Which Tissues Comprise the Vertebrate Skeleton? 000 Cartilage Provides Flexible Support and Connections 000 Bone Provides a Strong, Rigid Framework for the Body 000 Bone Remodeling Allows Skeletal Repair and Adaptation to Stresses 000 Health Watch: How Bones Heal 000 Health Watch: Osteoporosis-When Bones Become Brittle 000 39.5 How Does the Body Move? 000 Muscles Move the Skeleton Around Flexible Joints 000 Links to Life: Walk with a Dog 000 Case Study Revisited: Hidden Hazards of Space Travel 000 40 Animal Reproduction 000 Case Study: The Frozen Zoo 000 40.1 How Do Animals Reproduce? 000 Asexual Reproduction Does Not Involve the Fusion of Sperm and Egg 000 Sexual Reproduction Requires the Union of Sperm and Egg 000 40.2 How Does the Human Reproductive System Work? 000 The Ability to Reproduce Begins at Puberty 000 The Male Reproductive Tract Includes the Testes and Accessory Structures 000 The Female Reproductive Tract Includes the Ovaries and Accessory Structures 000 A Closer Look: Hormonal Control of the Menstrual Cycle 000 Copulation Allows Internal Fertilization 000 Health Watch: Sexually Transmitted Diseases 000 Health Watch: High-Tech Reproduction 000 40.3 How Can People Limit Fertility? 000 Permanent Contraception Can Be Achieved Through Sterilization 000 There Are Three General Approaches to Temporary Contraception 000 Scientific Inquiry: Seeking a Male Contraceptive 000 Case Study Revisited: The Frozen Zoo 000 41 Animal Development 000 Case Study: Faces of FAS 000 41.1 How Do Indirect and Direct Development Differ? 000 During Indirect Development, Animals Undergo a Radical Change in Body Form 000 Newborn Animals That Undergo Direct Development Resemble Miniature Adults 000 41.2 How Does Animal Development Proceed? 000 Cleavage of the Zygote Begins Development 000 Gastrulation Forms Three Tissue Layers 000 Adult Structures Develop 000 Sexual Maturation Is Controlled by Genes and the Environment 000 41.3 How Is Development Controlled? 000 Each Cell Contains the Entire Genetic Blueprint for the Organism 000 Scientific Inquiry: The Promise of Stem Cells 000 Gene Transcription Is Precisely Regulated During Development 000 41.4 How Do Humans Develop? 000 During the First Two Months, Rapid Differentiation and Growth Occur 000 The Placenta Secretes Hormones and Exchanges Materials Between Mother and Embryo 000 Health Watch: The Placenta Provides Only Partial Protection 000 Growth and Development Continue During the Last Seven Months 000 Development Culminates in Labor and Delivery 000 Links to Life: Why Is Human Childbirth So Difficult? 000 Milk Secretion Is Stimulated by Hormones of Pregnancy 000 Aging Is Inevitable 000 Case Study Revisited: Faces of FAS 000 UNIT SIX Plant Anatomy and Physiology 000 42 Plant Anatomy and Nutrient Transport 000 Case Study: Why Do Leaves Turn Red in the Fall? 000 42.1 How Are Plant Bodies Organized, and How Do They Grow? 000 Flowering Plants Consist of a Root System and a Shoot System 000 As Plants Grow, Meristem Cells Give Rise to Differentiated Cells 000 42.2 What Are the Tissues and Cell Types of Plants? 000 The Dermal Tissue System Covers the Plant Body 000 The Ground Tissue System Comprises Most of the Young Plant Body 000 The Vascular Tissue System Transports Water and Nutrients 000 42.3 What Are the Structures and Functions of Leaves, Roots, and Stems? 000 Leaves Are Nature's Solar Cells 000 Stems Elevate and Support the Plant Body 000 Roots Anchor the Plant, Absorb Nutrients, and Store Food 000 Evolutionary Connections: Interesting Adaptations of Roots, Stems, and Leaves 000 42.4 How Do Plants Acquire Mineral Nutrients? 000 Roots Absorb Mineral Nutrientss from Soil 000 A Closer Look: How Roots Absorb Minerals 000 Symbiotic Relationships Help Plants Acquire Nutrients 000 42.5 How Do Plants Move Water Upward from Roots to Leaves? 000 Water Movement in Xylem Is Explained by the Cohesion-Tension Theory 000 Adjustable Stomata Control the Rate of Transpiration 000 Earth Watch: Plants Help Regulate the Distribution of Water 000 42.6 How Do Plants Transport Sugars? 000 The Pressure-Flow Theory Explains Sugar Movement in Phloem 000 Case Study Revisited: Why Do Leaves Turn Red in the Fall? 000 43 Plant Reproduction and Development 000 Case Study: Gorgeous? Sure! But Hot? 000 43.1 What Are the Basic Features of Plant Life Cycles? 000 Plants Engage in Sex 000 Alternation of Generations Is Clearly Evident in Ferns and Mosses 000 43.2 How Is Reproduction in Seed Plants Adapted to Drier Environments? 000 43.3 What Is the Function and Structure of the Flower? 000 Most Flowers Lure Animals That Pollinate Them 000 Health Watch: Are You Allergic to Pollen? 000 Flowers Are the Reproductive Structure of Angiosperms 000 Complete Flowers Have Four Major Parts 000 Pollens Contains the Male Gametophyte 000 The Female Gametophyte Forms Within the Ovule of the Ovary 000 Pollenation of the Flower Leads to Fertilization 000 43.4 How Do Fruits and Seeds Develop? 000 The Fruit Develops from the Ovary 000 Earth Watch: On Dodos, Bats, and Disrupted Ecosystems 000 The Seed Develops from the Ovule 000 43.5 How Do Seeds Germinate and Grow? 000 Seed Dormancy Helps Ensure Germination at an Appropriate Time 000 Upon Germination, the Root Emerges First, Followed by the Shoot 000 Cotyledons Nourish the Sprouting Seed 000 43.6 What Are Some Adaptations for Pollination and Seed Dispersal? 000 Coevolution Matches Plants and Pollinators 000 Fruits Help Disperse Seeds 000 Case Study Revisited: Gorgeous? Sure! But Hot? 000 44 Plant Responses to the Environment 000 Case Study: Predacious Plants 000 44.1 What Are Plant Hormones, and How Do They Act? 000 Scientific Inquiry: How Were Plant Hormones Discovered? 000 44.2 How Do Hormones Regulate the Plant Life Cycle? 000 The Plant Life Cycle Begins with a Seed 000 Auxin Controls the Orientation of the Sprouting Seedling 000 The Genetically Determined Shape of the Mature Plant Is the Result of Interactions Among Hormones 000 Day Length Controls Flowering 000 Hormones Coordinate the Development of Seeds and Fruit 000 Senescence and Dormancy Prepare the Plant for Winter 000 44.3 Can Plants Communicate and Move Rapidly? 000 Plants May Summon "Bodyguards" When Attacked 000 Plants May Warn Their Neighbors and Offspring of Attacks 000 Some Plants Move Rapidly 000 Case Study Revisited: Predacious Plants 000 Appendix I: Metric System Conversions 000 Appendix II: Classification of Major Groups of Organisms 000 Glossary G1 Photo Credits P1 Index I1
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