Understanding Biology

Description

A concise and engaging biology text for biology majors, Understanding Biology 4e partnered with Connect emphasizes fundamentals concepts to help students better understand biology and focus on developing scientific skills.  This approach utilizes the Vision and Change guidelines of Core Concepts and Core Skills while helping students begin the process of becoming a scientist. Cover Title Copyright Brief Contents About the Authors Changes to This Edition Acknowledgments A Learning Path to Understanding Biology Contents PART I: The Molecular Basis of Life 1 The Science of Biology Concept 1.1 The Diversity of Life Is Overwhelming Concept 1.2 Biology Is the Science of Life Concept 1.3 Science Is Based on Both Observation and Reasoning Concept 1.4 The Study of Evolution Is a Good Example of Scientific Inquiry Concept 1.5 A Few Important Concepts Form the Core of Biology Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 2 The Nature of Molecules and the Properties of Water Concept 2.1 All Matter Is Composed of Atoms Concept 2.2 The Elements in Living Systems Have Low Atomic Masses Concept 2.3 Molecules Are Collections of Atoms Held Together by Chemical Bonds Concept 2.4 The Properties of Water Result from Its Polar Nature Concept 2.5 Water Molecules Can Dissociate into Ions Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 3 The Chemical Building Blocks of Life Concept 3.1 Carbon Provides the Framework of Biological Molecules Concept 3.2 Carbohydrates Form Both Structural and Energy- Storing Molecules Concept 3.3 Proteins Are the Tools of the Cell Concept 3.4 Nucleic Acids Store and Express Genetic Information Concept 3.5 Hydrophobic Lipids Form Fats and Membranes Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path PART II: Biology of the Cell 4 Cell Structure Concept 4.1 All Living Organisms Are Composed of Cells Concept 4.2 Prokaryotic Cells Are Relatively Simple Concept 4.3 Eukaryotic Cells Are Highly Compartmentalized Concept 4.4 Membranes Organize the Cell Interior into Functional Compartments Concept 4.5 Mitochondria and Chloroplasts Are Energy-Processing Organelles Concept 4.6 An Internal Skeleton Supports the Shape of Cells Concept 4.7 Extracellular Structures Protect Cells Concept 4.8 Cell-to-Cell Connections Determine How Adjacent Cells Interact Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 5 Membranes Concept 5.1 Membranes Are Phospholipid Bilayers with Embedded Proteins Concept 5.2 Phospholipids Provide a Membrane's Structural Foundation Concept 5.3 Membrane Proteins Enable a Broad Range of Interactions with the Environment Concept 5.4 Passive Transport Moves Molecules Across Membranes by Diffusion Concept 5.5 Active Transport Across Membranes Requires Energy Concept 5.6 Bulky Materials Cross Membranes Within Vesicles Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 6 Energy and Metabolism Concept 6.1 Energy Flows Through Living Systems Concept 6.2 The Laws of Thermodynamics Govern All Energy Changes Concept 6.3 ATP Is the Energy Currency of Cells Concept 6.4 Enzymes Speed Up Reactions by Lowering Activation Energy Concept 6.5 Metabolism Is the Sum of a Cell's Chemical Activities Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 7 How Cells Harvest Energy Concept 7.1 Cells Harvest Energy from Organic Compounds by Oxidation Concept 7.2 Glycolysis Splits Glucose and Yields a Small Amount of ATP Concept 7.3 The Citric Acid Cycle Is the Oxidative Core of Cellular Respiration Concept 7.4 Electrons Removed by Oxidation Pass Along an Electron Transport Chain Concept 7.5 The Total Energy Yield of Aerobic Respiration Far Exceeds That of Glycolysis Concept 7.6 Aerobic Respiration Is Regulated by Feedback Inhibition Concept 7.7 Some Forms of Energy Metabolism Do Not Require O2 Concept 7.8 Carbohydrates Are Not the Only Energy Source Used by Heterotrophs Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 8 Photosynthesis Concept 8.1 Photosynthesis Uses Sunlight to Power the Synthesis of Organic Molecules Concept 8.2 Experiments Revealed That Photosynthesis Is a Chemical Process Concept 8.3 Pigments Capture Energy from Sunlight Concept 8.4 Photosynthetic Pigments Are Organized into Photosystems Concept 8.5 Energy from Sunlight Is Used to Produce a Proton Gradient Concept 8.6 Carbon Fixation Incorporates CO2 into Organic Molecules Concept 8.7 Photorespiration Short-Circuits Photosynthesis Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 9 Cell Communication Concept 9.1 The Cells of Multicellular Organisms Communicate Concept 9.2 Signal Transduction Begins with Cellular Receptors Concept 9.3 Intracellular Receptors Respond to Signals by Regulating Gene Expression Concept 9.4 Protein Kinase Receptors Respond to Signals by Phosphorylating Proteins Concept 9.5 G Protein–Coupled Receptors Respond to Signals Through Effector Proteins Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 10 How Cells Divide Concept 10.1 Bacterial Cell Division Is Clonal Concept 10.2 Eukaryotes Have Large, Linear Chromosomes Concept 10.3 The Eukaryotic Cell Cycle Is Complex and Highly Organized Concept 10.4 During Interphase, Cells Grow and Prepare for Mitosis Concept 10.5 In Mitosis, Chromosomes Segregate Concept 10.6 Events of the Cell Cycle Are Carefully Regulated Concept 10.7 Cancer Is a Failure of Cell-Cycle Control Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path PART III: Genetics and Molecular Biology 11 Sexual Reproduction and Meiosis Concept 11.1 Sexual Reproduction Requires Meiosis Concept 11.2 Meiosis Consists of Two Divisions with One Round of DNA Replication Concept 11.3 The Process of Meiosis Involves Intimate Interactions Between Homologs Concept 11.4 Meiosis Has Four Distinct Features Concept 11.5 Genetic Variation Is the Evolutionary Consequence of Sex Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 12 Patterns of Inheritance Concept 12.1 Experiments Carried Out by Mendel Explain Inheritance Concept 12.2 Mendel's Principle of Segregation Accounts for 3:1 Phenotypic Ratios Concept 12.3 Mendel's Principle of Independent Assortment Asserts That Genes Segregate Independently Concept 12.4 Probability Allows Us to Predict the Results of Crosses Concept 12.5 Extending Mendel's Model Provides a Clearer View of Genetics in Action Concept 12.6 Genotype Dictates Phenotype by Specifying Protein Sequences Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 13 The Chromosomal Basis of Inheritance Concept 13.1 Sex Linkage and the Chromosomal Theory of Inheritance Concept 13.2 There Are Two Major Exceptions to Chromosomal Inheritance Concept 13.3 Some Genes Do Not Assort Independently: Linkage Concept 13.4 Genetic Crosses Provide Data for Genetic Maps Concept 13.5 Changes in Chromosome Number Can Have Drastic Effects Concept 13.6 Inheritance in Humans Can Be Studied by Analyzing Pedigrees Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 14 DNA: The Genetic Material Concept 14.1 DNA Is the Genetic Material Concept 14.2 The DNA Molecule Is a Double Helix Concept 14.3 Both Strands Are Copied During DNA Replication Concept 14.4 Prokaryotes Organize the Enzymes Used to Duplicate DNA Concept 14.5 Eukaryotic Chromosomes Are Large and Linear Concept 14.6 Cells Repair Damaged DNA Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 15 Genes and How They Work Concept 15.1 Experiments Have Revealed the Nature of Genes Concept 15.2 The Genetic Code Relates Information in DNA and Protein Concept 15.3 Prokaryotes Exhibit All the Basic Features of Transcription Concept 15.4 Eukaryotes Use Three Polymerases and Extensively Modify Transcripts Concept 15.5 Eukaryotic Genes May Contain Noncoding Sequences Concept 15.6 The Ribosome Is the Machine of Protein Synthesis Concept 15.7 The Process of Translation Is Complex and Energy-Expensive Concept 15.8 Mutations Are Heritable Changes in Genetic Material Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 16 Control of Gene Expression Concept 16.1 All Organisms Control Expression of Their Genes Concept 16.2 Regulatory Proteins Control Genes by Interacting with Specific DNA Nucleotide Sequences Concept 16.3 Prokaryotes Regulate Their Genes in Clusters Concept 16.4 Transcription Factors Control Gene Transcription in Eukaryotes Concept 16.5 Chromatin Structure Affects Gene Expression Concept 16.6 Eukaryotic Genes Are Also Regulated After Transcription Concept 16.7 Gene Regulation Determines How Cells Will Develop Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 17 Biotechnology Concept 17.1 Enzymes Allow the Creation of Recombinant Molecules In Vitro Concept 17.2 The Polymerase Chain Reaction Is Used to Amplify Specific DNA Sequences Concept 17.3 Molecular Tools Allow Us to Analyze and Modify Genetic Variation Concept 17.4 Transgenic Organisms Are Used to Analyze Gene Function Concept 17.5 Genetic Tools Are Changing Modern Medicine Concept 17.6 Genetic Engineering Is Used in Industry and Agriculture Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 18 Genomics Concept 18.1 Mapping Identifies and Locates Functional Elements in Genomes Concept 18.2 The Modernization of DNA Sequencing Has Accelerated Discovery Concept 18.3 Genome Projects Reveal Insights into Medicine and Agriculture Concept 18.4 Genome Annotation Assigns Functional Information to Genomes Concept 18.5 Genome Comparisons Provide Information About Genomic Structure and Function Concept 18.6 Comparative Genomics Informs Evolutionary Biology Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path PART IV: Evolution 19 Genes Within Populations Concept 19.1 Natural Populations Exhibit Genetic Variation Concept 19.2 Frequencies of Alleles Can Change Concept 19.3 Five Agents Are Responsible for Evolutionary Change Concept 19.4 Selection Can Act on Traits Affected by Many Genes Concept 19.5 Natural Selection Can Be Studied Experimentally Concept 19.6 Fitness Is a Measure of Evolutionary Success Concept 19.7 Evolutionary Processes Sometimes Maintain Variation Concept 19.8 Sexual Selection Determines Reproductive Success Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 20 The Evidence for Evolution Concept 20.1 The Beaks of Darwin's Finches Provide Evidence of Natural Selection Concept 20.2 Peppered Moths and Industrial Melanism Illustrate Natural Selection in Action Concept 20.3 Human-Initiated Artificial Selection Is Also a Powerful Agent of Change Concept 20.4 Fossils Provide Direct Evidence of Evolution Concept 20.5 Anatomical Evidence for Evolution Is Extensive and Persuasive Concept 20.6 Genes Carry a Molecular Record of the Evolutionary Past Concept 20.7 Natural Selection Favors Convergent Evolution in Similar Environments Concept 20.8 Addressing Common Criticisms of Evolutionary Theory Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 21 The Origin of Species Concept 21.1 The Biological Species Concept Highlights Reproductive Isolation Concept 21.2 Natural Selection May Reinforce Reproductive Isolation Concept 21.3 Natural Selection and Genetic Drift Play Key Roles in Speciation Concept 21.4 Speciation Is Influenced by Geography Concept 21.5 Adaptive Radiation Requires Both Speciation and Habitat Diversity Concept 21.6 The Pace of Evolution Varies Concept 21.7 Speciation and Extinction Have Molded Biodiversity Through Time Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path PART V: The Diversity of Life 22 Systematics and Phylogeny Concept 22.1 Systematics Reconstructs Evolutionary Relationships Concept 22.2 Cladistics Focuses on Traits Derived from a Common Ancestor Concept 22.3 Classification Is a Labeling Process, Not an Evolutionary Reconstruction Concept 22.4 Taxonomy Attempts to Classify Organisms in an Evolutionary Context Concept 22.5 The Largest Taxa Are Domains Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 23 Prokaryotes and Viruses Concept 23.1 Prokaryotes Are the Most Ancient Organisms Concept 23.2 Prokaryotes Have an Organized but Simple Structure Concept 23.3 The Genetics of Prokaryotes Focuses on DNA Transfer Concept 23.4 Prokaryotic Metabolism Is Diverse Concept 23.5 Bacteria Cause Important Human Diseases Concept 23.6 Viruses Are Not Organisms Concept 23.7 Bacterial Viruses Infect by DNA Injection Concept 23.8 Animal Viruses Infect by Endocytosis Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 24 Protists Concept 24.1 Protists, the First Eukaryotes, Arose by Endosymbiosis Concept 24.2 Protists Are a Very Diverse Group Concept 24.3 The Rough Outlines of Protist Phylogeny Are Becoming Clearer Concept 24.4 Excavata Are Flagellated Protists Lacking Mitochondria Concept 24.5 SAR: Stramenopiles and Alveolates Exhibit Secondary Endosymbiosis Concept 24.6 SAR: Rhizaria Have Silicon Exoskeletons or Limestone Shells Concept 24.7 Archaeplastida Are Descended from a Single Endosymbiosis Event Concept 24.8 Amoebozoa and Opisthokonta Are Closely Related Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 25 Fungi Concept 25.1 Fungi Have Unique Reproductive and Nutritional Strategies Concept 25.2 Fungi Have an Enormous Ecological Impact Concept 25.3 Fungi Are Important Plant and Animal Pathogens Concept 25.4 Fungi Are Taxonomically Diverse Concept 25.5 Microsporidia Are Unicellular Parasites Concept 25.6 Chytridiomycota and Relatives: Fungi with Zoospores Concept 25.7 Zygomycota Produce Zygotes Concept 25.8 Glomeromycota Are Asexual Plant Symbionts Concept 25.9 Basidiomycota Are the Mushroom Fungi Concept 25.10 Ascomycota Are the Most Diverse Phylum of Fungi Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 26 Plants Concept 26.1 Land Plants Are Multicellular Autotrophs Adapted to Terrestrial Life Concept 26.2 Bryophytes Have a Dominant Gametophyte Generation Concept 26.3 Seedless Vascular Plants Evolved Roots, Stems, and Leaves Concept 26.4 Lycophytes Have a Dominant Sporophyte Generation Concept 26.5 Pterophytes Are Ferns and Their Relatives Concept 26.6 Seed Plants Were a Key Step in Plant Evolution Concept 26.7 Gymnosperms Are Plants with "Naked Seeds" Concept 26.8 Angiosperms Are Flowering Plants Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 27 Animal Diversity Concept 27.1 The Diversity of Animal Body Plans Arose by a Series of Evolutionary Innovations Concept 27.2 Molecular Data Are Clarifying the Animal Phylogenetic Tree Concept 27.3 True Tissue Evolved in Simple Animals Concept 27.4 Flatworms and Rotifers Are Very Simple Bilaterians Concept 27.5 Mollusks and Annelids Are the Largest Groups of Lophotrochozoans Concept 27.6 Lophophorates Are Very Simple Marine Organisms Concept 27.7 Nematodes and Arthropods Are Both Large Groups of Ecdysozoans Concept 27.8 Deuterostomes Are Composed of Echinoderms and Chordates Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 28 Vertebrates Concept 28.1 Nonvertebrate Chordates Do Not Form Bone Concept 28.2 Almost All Chordates Are Vertebrates Concept 28.3 Fishes Are the Earliest and Most Diverse Vertebrates Concept 28.4 Amphibians Are Moist-Skinned Descendants of the Early Tetrapods Concept 28.5 Reptiles Are Fully Adapted to Terrestrial Living Concept 28.6 Birds Are Essentially Flying Reptiles Concept 28.7 Mammals Are the Least Diverse of Vertebrates Concept 28.8 Primates Include Lemurs, Monkeys, Apes, and Humans Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path PART VI: Plant Form and Function 29 Plant Form Concept 29.1 Meristems Articulate the Body Plan Concept 29.2 Plants Contain Three Main Tissues Concept 29.3 Roots Have Four Growth Zones Concept 29.4 Stems Provide Support for Aboveground Organs Concept 29.5 Leaves Are a Plant's Photosynthetic Organs Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 30 Flowering Plant Reproduction Concept 30.1 Reproduction Starts with Flowering Concept 30.2 Flowers Attract Pollinators Concept 30.3 Fertilization Leads to Embryogenesis Concept 30.4 Seeds Protect Angiosperm Embryos Concept 30.5 Fruits Promote Seed Dispersal Concept 30.6 Germination Begins Seedling Growth Concept 30.7 Plant Life Spans Vary Widely Concept 30.8 Asexual Reproduction Is Common Among Flowering Plants Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 31 The Living Plant Concept 31.1 Water Moves Through Plants Based on Potential Differences Concept 31.2 Roots Absorb Minerals and Water Concept 31.3 Xylem Transports Water from Root to Shoot Concept 31.4 Transpiration Rate Reflects Environmental Conditions Concept 31.5 Plants Are Adapted to Water Stress Concept 31.6 Phloem Transports Organic Molecules Concept 31.7 Plants Require a Variety of Nutrients Concept 31.8 Plants Use Hormones to Regulate Growth Concept 31.9 Plant Growth Is Responsive to Light Concept 31.10 Plant Growth Is Sensitive to Gravity Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path PART VII: Animal Form and Function 32 The Animal Body and How It Moves Concept 32.1 The Vertebrate Body Has a Hierarchical Organization Concept 32.2 Epithelial Tissue Covers Body Surfaces Concept 32.3 Nerve Tissue Conducts Signals Rapidly Concept 32.4 Connective Tissue Supports the Body Concept 32.5 Muscle Tissue Powers the Body's Movements Concept 32.6 Skeletal Systems Anchor the Body's Muscles Concept 32.7 Vertebrate Endoskeletons Are Made of Bone Concept 32.8 Muscles Contract Because Their Myofilaments Slide Concept 32.9 Animal Locomotion Takes Many Forms Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 33 The Nervous System Concept 33.1 The Nervous System Directs the Body's Actions Concept 33.2 Neurons Maintain a Resting Potential Across the Plasma Membrane Concept 33.3 Action Potentials Propagate Nerve Impulses Concept 33.4 Synapses Are Where Neurons Communicate with Other Cells Concept 33.5 The Central Nervous System Includes the Brain and Spinal Cord Concept 33.6 The Peripheral Nervous System Consists of Both Sensory and Motor Neurons Concept 33.7 Sensory Receptors Provide Information About the Body's Environment Concept 33.8 Mechanoreceptors Sense Touch and Pressure Concept 33.9 Sounds and Body Position Are Sensed by Vibration Detectors Concept 33.10 Taste, Smell, and pH Senses Utilize Chemoreceptors Concept 33.11 Vision Employs Photoreceptors to Perceive Objects at a Distance Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 34 Fueling the Body's Metabolism Concept 34.1 Vertebrate Digestive Systems Are Tubular Tracts Concept 34.2 Food Is Processed as It Passes Through the Digestive Tract Concept 34.3 The Digestive Tract Is Regulated by the Nervous System and Hormones Concept 34.4 Respiratory Systems Promote Efficient Exchange of Gases Concept 34.5 Gills Provide for Efficient Gas Exchange in Water Concept 34.6 Lungs Are the Respiratory Organs of Terrestrial Vertebrates Concept 34.7 Oxygen and Carbon Dioxide Are Transported by Fundamentally Different Mechanisms Concept 34.8 Circulating Blood Carries Metabolites and Gases to the Tissues Concept 34.9 Vertebrate Circulatory Systems Put a Premium on Efficient Circulation Concept 34.10 The Four Chambers of the Heart Contract in a Cycle Concept 34.11 The Circulatory Highway Is Composed of Arteries, Capillaries, and Veins Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 35 Maintaining Homeostasis Concept 35.1 Homeostasis Maintains a Constant Internal Environment Concept 35.2 Hormones Are Chemical Messages That Direct Body Processes Concept 35.3 The Pituitary and the Hypothalamus Are the Body's Control Centers Concept 35.4 Peripheral Endocrine Glands Play Major Roles in Homeostasis Concept 35.5 Animals Are Osmoconformers or Osmoregulators Concept 35.6 The Kidney Maintains Osmotic Homeostasis in Mammals Concept 35.7 Hormones Control Osmoregulation Concept 35.8 The Immune System Defends the Body Concept 35.9 Cell-Mediated Immunity Involves Helper and Killer T Cells Concept 35.10 In Humoral Immunity, B Cells Produce Protective Antibodies Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 36 Reproduction and Development Concept 36.1 Mammals Are Viviparous Concept 36.2 The Human Male Reproductive System Is Typical of Mammals Concept 36.3 The Human Female Reproductive System Undergoes Cyclic Gamete Development Concept 36.4 The First Step in Development Is Fertilization Concept 36.5 Cells of the Early Embryo Are Totipotent Concept 36.6 Cleavage Leads to the Blastula Stage Concept 36.7 Gastrulation Forms the Basic Body Plan of the Embryo Concept 36.8 The Body's Organs Form in Organogenesis Concept 36.9 Human Development Takes Nine Months Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path PART VIII: Ecology and Behavior 37 Behavioral Biology Concept 37.1 An Animal's Genome Influences Its Behavior Concept 37.2 Learning Also Influences Behavior Concept 37.3 Thinking Directs the Behavior of Many Animals Concept 37.4 Migratory Behavior Is Both Innate and Learned Concept 37.5 Animal Communication Plays a Key Role in Ecological and Social Behavior Concept 37.6 Behavior Evolves Adaptively Concept 37.7 Behavioral Ecology Examines the Adaptive Significance of Behaviors Concept 37.8 Behavioral Strategies Have Evolved to Maximize Reproductive Success Concept 37.9 Some Behaviors Decrease Fitness to Benefit Other Individuals Concept 37.10 Group Living Has Evolved in Both Insects and Vertebrates Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 38 Ecology of Individuals and Populations Concept 38.1 Populations Are Groups of a Single Species in One Place Concept 38.2 Population Growth Depends upon Members' Age and Sex Concept 38.3 Evolution Favors Life Histories That Maximize Lifetime Reproductive Success Concept 38.4 Environment Limits Population Growth Concept 38.5 Resource Availability Regulates Population Growth Concept 38.6 Earth's Human Population Is Growing Explosively Concept 38.7 Pandemics and Human Health Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 39 Community Ecology and Ecosystem Dynamics Concept 39.1 Competition Shapes How Species Live Together in Communities Concept 39.2 Predator–Prey Relationships Foster Coevolution Concept 39.3 Cooperation Among Species Can Lead to Coevolution Concept 39.4 Ecological Succession Is a Consequence of Habitat Alteration Concept 39.5 Chemical Elements Move Through Ecosystems in Biogeochemical Cycles Concept 39.6 Energy Flows Through Ecosystems in One Direction Concept 39.7 Biodiversity May Increase Ecosystem Stability Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path 40 The Living World Concept 40.1 Ecosystems Are Shaped by Sun, Wind, and Water Concept 40.2 Earth Has 14 Major Terrestrial Ecosystems, Called Biomes Concept 40.3 Freshwater Habitats Occupy Less Than 2% of Earth's Surface Concept 40.4 Marine Habitats Dominate the Earth Concept 40.5 Humanity's Pollution Is Severely Impacting the Biosphere Concept 40.6 Human Activity Is Altering Earth's Climate Inquiry & Analysis Retracing the Learning Path Assessing the Learning Path Appendix: Answer Key Glossary A B C D E F G H I J K L M N O P Q R S T U V W X Y Z Index A B C D E F G H I J K L M N O P Q R S T U V W X Y Z