Table of contents for Biology : life on earth / Teresa Audesirk, Gerald Audesirk, Bruce E. Byers.

Bibliographic record and links to related information available from the Library of Congress catalog.

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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
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?
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?
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?
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
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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