Campbell Biology

Lisa A. Urry Lisa Urry (Chapter 1 and Units 1, 2, and 3) is Professor of Biology and Chair of the Biology Department at Mills College in Oakland, California, and a Visiting Scholar at the University of California, Berkeley. After graduating from Tufts University with a double major in biology and French, Lisa completed her Ph.D. in molecular and developmental biology at Massachusetts Institute of Technology (MIT) in the MIT/Woods Hole Oceanographic Institution Joint Program. She has published a number of research papers, most of them focused on gene expression during embryonic and larval development in sea urchins. Lisa has taught a variety of courses, from introductory biology to developmental biology and senior seminar. As a part of her mission to increase understanding of evolution, Lisa also teaches a nonmajors course called Evolution for Future Presidents and is on the Teacher Advisory Board for the Understanding Evolution website developed by the University of California Museum of Paleontology. Lisa is also deeply committed to promoting opportunities for women and underrepresented minorities in science. Michael L. CainMichael Cain (Units 4, 5, and 8) is an ecologist and evolutionary biologist who is now writing full-time. Michael earned a joint degree in biology and math at Bowdoin College, an M.Sc. from Brown University, and a Ph.D. in ecology and evolutionary biology from Cornell University. As a faculty member at NEW! Mexico State University and Rose-Hulman Institute of Technology, he taught a wide range of courses, including introductory biology, ecology, evolution, botany, and conservation biology. Michael is the author of dozens of scientific papers on topics that include foraging behavior in insects and plants, long-distance seed dispersal, and speciation in crickets. Michael is also the lead author of an ecology textbook. Steven A. WassermanSteve Wasserman (Unit 7) is Professor of Biology at the University of California, San Diego (UCSD). He earned his A.B. in biology from Harvard University and his Ph.D. in biological sciences from MIT. Through his research on regulatory pathway mechanisms in the fruit fly Drosophila, Steve has contributed to the fields of developmental biology, reproduction, and immunity. As a faculty member at the University of Texas Southwestern Medical Center and UCSD, he has taught genetics, development, and physiology to undergraduate, graduate, and medical students. He currently focuses on teaching introductory biology. He has also served as the research mentor for more than a dozen doctoral students and more than 50 aspiring scientists at the undergraduate and high school levels. Steve has been the recipient of distinguished scholar awards from both the Markey Charitable Trust and the David and Lucille Packard Foundation. In 2007, he received UCSD’s Distinguished Teaching Award for undergraduate teaching. Peter V. MinorskyPeter Minorsky (Unit 6) is Professor of Biology at Mercy College in New York, where he teaches introductory biology, evolution, ecology, and botany. He received his A.B. in biology from Vassar College and his Ph.D. in plant physiology from Cornell University. He is also the science writer for the journal Plant Physiology. After a postdoctoral fellowship at the University of Wisconsin at Madison, Peter taught at Kenyon College, Union College, Western Connecticut State University, and Vassar College. His research interests concern how plants sense environmental change. Peter received the 2008 Award for Teaching Excellence at Mercy College. Jane B. ReeceThe head of the author team for recent editions of CAMPBELL BIOLOGY, Jane Reece was Neil Campbell’s longtime collaborator.  Earlier, Jane taught biology at Middlesex County College and Queensborough Community College. She holds an A.B. in biology from Harvard University, an M.S. in microbiology from Rutgers University, and a Ph.D. in bacteriology from the University of California, Berkeley. Jane’s research as a doctoral student and postdoctoral fellow focused on genetic recombination in bacteria. Besides her work on the Campbell textbooks for biology majors, she has been an author of Campbell Biology: Concepts & Connections, Campbell Essential Biology, and The World of the Cell. Neil A. CampbellNeil Campbell (1946–2004) combined the investigative nature of a research scientist with the soul of an experienced and caring teacher. He earned his M.A. in zoology from the University of California, Los Angeles, and his Ph.D. in plant biology from the University of California, Riverside, where he received the Distinguished Alumnus Award in 2001. Neil published numerous research articles on desert and coastal plants and how the sensitive plant (Mimosa) and other legumes move their leaves. His 30 years of teaching in diverse environments included introductory biology courses at Cornell University, Pomona College, and San Bernardino Valley College, where he received the college’s first Outstanding Professor Award in 1986. He was a visiting scholar in the Department of Botany and Plant Sciences at the University of California, Riverside. Neil was the lead author of Campbell Biology: Concepts & Connections, Campbell Essential Biology, and CAMPBELL BIOLOGY.

• 1  Evolution, the Themes of Biology, and Scientific Inquiry  Inquiring About Life CONCEPT 1.1 The study of life reveals common themes CONCEPT 1.2 The Core Theme: Evolution accounts for the unity and diversity of life CONCEPT 1.3 In studying nature, scientists make observations and form and test hypotheses CONCEPT 1.4 Science benefits from a cooperative approach and diverse viewpoints  UNIT 1  THE CHEMISTRY OF LIFE 2  The Chemical Context of Life A Chemical Connection to Biology CONCEPT 2.1 Matter consists of chemical elements in pure form and in combinations called compounds CONCEPT 2.2 An element’s properties depend on the structure of its atoms CONCEPT 2.3 The formation and function of molecules depend on chemical bonding between atoms CONCEPT 2.4 Chemical reactions make and break chemical bonds 3  Water and Life The Molecule That Supports All of Life CONCEPT 3.1 Polar covalent bonds in water molecules result in hydrogen bonding CONCEPT 3.2 Four emergent properties of water contribute to Earth’s suitability for life CONCEPT 3.3 Acidic and basic conditions affect living organisms 4  Carbon and the Molecular Diversity of Life Carbon: The Backbone of Life CONCEPT 4.1 Organic chemistry is the study of carbon compounds CONCEPT 4.2 Carbon atoms can form diverse molecules by bonding to four other atoms CONCEPT 4.3 A few chemical groups are key to molecular function 5  The Structure and Function of Large Biological Molecules The Molecules of Life CONCEPT 5.1 Macromolecules are polymers, built from monomers CONCEPT 5.2 Carbohydrates serve as fuel and building material CONCEPT 5.3 Lipids are a diverse group of hydrophobic molecules CONCEPT 5.4 Proteins include a diversity of structures, resulting in a wide range of functions CONCEPT 5.5 Nucleic acids store, transmit, and help express hereditary information CONCEPT 5.6 Genomics and proteomics have transformed biological inquiry and applications   UNIT 2  THE CELL 6  A Tour of the Cell The Fundamental Units of Life CONCEPT 6.1 Biologists use microscopes and biochemistry to study cells CONCEPT 6.2 Eukaryotic cells have internal membranes that compartmentalize their functions CONCEPT 6.3 The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes CONCEPT 6.4 The endomembrane system regulates protein traffic and performs metabolic functions CONCEPT 6.5 Mitochondria and chloroplasts change energy from one form to another CONCEPT 6.6 The cytoskeleton is a network of fibers that organizes structures and activities in the cell CONCEPT 6.7 Extracellular components and connections between cells help coordinate cellular activities CONCEPT 6.8 A cell is greater than the sum of its parts7  Membrane Structure and Function Life at the Edge CONCEPT 7.1 Cellular membranes are fluid mosaics of lipids and proteins CONCEPT 7.2 Membrane structure results in selective permeability CONCEPT 7.3 Passive transport is diffusion of a substance across a membrane with no energy investment CONCEPT 7.4 Active transport uses energy to move solutes against their gradients CONCEPT 7.5 Bulk transport across the plasma membrane occurs by exocytosis and endocytosis 8  An Introduction to MetabolismThe Energy of Life CONCEPT 8.1 An organism’s metabolism transforms matter and energy, subject to the laws of thermodynamics CONCEPT 8.2 The free-energy change of a reaction tells us whether or not the reaction occurs spontaneously CONCEPT 8.3 ATP powers cellular work by coupling exergonic reactions to endergonic reactions CONCEPT 8.4 Enzymes speed up metabolic reactions by lowering energy barriers CONCEPT 8.5 Regulation of enzyme activity helps control metabolism 9  Cellular Respiration and Fermentation Life Is Work CONCEPT 9.1 Catabolic pathways yield energy by oxidizing organic fuels CONCEPT 9.2 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate CONCEPT 9.3 After pyruvate is oxidized, the citric acid cycle completes the energy-yielding oxidation of organic molecules CONCEPT 9.4 During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis CONCEPT 9.5 Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen CONCEPT 9.6 Glycolysis and the citric acid cycle connect to many other metabolic pathways 10  Photosynthesis The Process That Feeds the Biosphere CONCEPT 10.1 Photosynthesis converts light energy to the chemical energy of food CONCEPT 10.2 The light reactions convert solar energy to the chemical energy of ATP and NADPH CONCEPT 10.3 The Calvin cycle uses the chemical energy of ATP and NADPH to reduce CO2 to sugar CONCEPT 10.4 Alternative mechanisms of carbon fixation have evolved in hot, arid climatesCONCEPT 10.5Life depends on photosynthesis  11  Cell Communication Cellular Messaging CONCEPT 11.1 External signals are converted to responses within the cell CONCEPT 11.2 Reception: A signaling molecule binds to a receptor protein, causing it to change shape CONCEPT 11.3 Transduction: Cascades of molecular interactions relay signals from receptors to target molecules in the cell CONCEPT 11.4 Response: Cell signaling leads to regulation of transcription or cytoplasmic activities CONCEPT 11.5 Apoptosis integrates multiple cell-signaling pathways 12  The Cell Cycle The Key Roles of Cell Division CONCEPT 12.1 Most cell division results in genetically identical daughter cells CONCEPT 12.2 The mitotic phase alternates with interphase in the cell cycle CONCEPT 12.3 The eukaryotic cell cycle is regulated by a molecular control system  UNIT 3  GENETICS 13  Meiosis and Sexual Life Cycles Variations on a Theme CONCEPT 13.1 Offspring acquire genes from parents by inheriting chromosomes CONCEPT 13.2 Fertilization and meiosis alternate in sexual life cycles CONCEPT 13.3 Meiosis reduces the number of chromosome sets from diploid to haploid CONCEPT 13.4 Genetic variation produced in sexual life cycles contributes to evolution 14  Mendel and the Gene Idea Drawing from the Deck of Genes CONCEPT 14.1 Mendel used the scientific approach to identify two laws of inheritance CONCEPT 14.2 Probability laws govern Mendelian inheritance CONCEPT 14.3 Inheritance patterns are often more complex than predicted by simple Mendelian genetics CONCEPT 14.4 Many human traits follow Mendelian patterns of inheritance 15 The Chromosomal Basis of Inheritance Locating Genes Along Chromosomes CONCEPT 15.1 Morgan showed that Mendelian inheritance has its physical basis in the behavior of chromosomes: scientific inquiry CONCEPT 15.2 Sex-linked genes exhibit unique patterns of inheritance CONCEPT 15.3 Linked genes tend to be inherited together because they are located near each other on the same chromosome CONCEPT 15.4 Alterations of chromosome number or structure cause some genetic disorders CONCEPT 15.5 Some inheritance patterns are exceptions to standard Mendelian inheritance 16  The Molecular Basis of Inheritance Life’s Operating Instructions CONCEPT 16.1 DNA is the genetic material CONCEPT 16.2 Many proteins work together in DNA replication and repair CONCEPT 16.3 A chromosome consists of a DNA molecule packed together with proteins 17  Gene Expression: From Gene to Protein The Flow of Genetic Information CONCEPT 17.1 Genes specify proteins via transcription and translation CONCEPT 17.2 Transcription is the DNA-directed synthesis of RNA: a closer look CONCEPT 17.3 Eukaryotic cells modify RNA after transcription CONCEPT 17.4 Translation is the RNA-directed synthesis of a polypeptide: a closer look CONCEPT 17.5 Mutations of one or a few nucleotides can affect protein structure and function 18  Regulation of Gene Expression Beauty in the Eye of the BeholderCONCEPT 18.1 Bacteria often respond to environmental change by regulating transcription CONCEPT 18.2 Eukaryotic gene expression is regulated at many stages CONCEPT 18.3 Noncoding RNAs play multiple roles in controlling gene expression CONCEPT 18.4 A program of differential gene expression leads to the different cell types in a multicellular organism CONCEPT 18.5 Cancer results from genetic changes that affect cell cycle control 19  Viruses A Borrowed Life CONCEPT 19.1 A virus consists of a nucleic acid surrounded by a protein coat CONCEPT 19.2 Viruses replicate only in host cells CONCEPT 19.3 Viruses and prions are formidable pathogens in animals and plants 20  DNA Tools and Biotechnology The DNA Toolbox CONCEPT 20.1 DNA sequencing and DNA cloning are valuable tools for genetic engineering and biological inquiry CONCEPT 20.2 Biologists use DNA technology to study gene expression and function CONCEPT 20.3 Cloned organisms and stem cells are useful for basic research and other applications CONCEPT 20.4 The practical applications of DNA-based biotechnology affect our lives in many ways 21  Genomes and Their Evolution Reading the Leaves from the Tree of Life CONCEPT 21.1 The Human Genome Project fostered development of faster, less expensive sequencing techniques CONCEPT 21.2 Scientists use bioinformatics to analyze genomes and their functions CONCEPT 21.3 Genomes vary in size, number of genes, and gene density CONCEPT 21.4 Multicellular eukaryotes have a lot of noncoding DNA and many multigene families CONCEPT 21.5 Duplication, rearrangement, and mutation of DNA contribute to genome evolution CONCEPT 21.6 Comparing genome sequences provides clues to evolution and development  UNIT 4  MECHANISMS OF EVOLUTION 22  Descent with Modification: A Darwinian View of Life Endless Forms Most Beautiful CONCEPT 22.1 The Darwinian revolution challenged traditional views of a young Earth inhabited by unchanging speciesCONCEPT 22.2 Descent with modification by natural selection explains the adaptations of organisms and the unity and diversity of life CONCEPT 22.3 Evolution is supported by an overwhelming amount of scientific evidence 23  The Evolution of Populations The Smallest Unit of Evolution CONCEPT 23.1 Genetic variation makes evolution possibleCONCEPT 23.2 The Hardy-Weinberg equation can be used to test whether a population is evolving CONCEPT 23.3 Natural selection, genetic drift, and gene flow can alter allele frequencies in a population CONCEPT 23.4 Natural selection is the only mechanism that consistently causes adaptive evolution 24  The Origin of Species That “Mystery of Mysteries” CONCEPT 24.1 The biological species concept emphasizes reproductive isolation CONCEPT 24.2 Speciation can take place with or without geographic separation CONCEPT 24.3 Hybrid zones reveal factors that cause reproductive isolation CONCEPT 24.4 Speciation can occur rapidly or slowly and can result from changes in few or many genes 25  The History of Life on EarthA Surprise in the Desert CONCEPT 25.1 Conditions on early Earth made the origin of life possible CONCEPT 25.2 The fossil record documents the history of life CONCEPT 25.3 Key events in life’s history include the origins of unicellular and multicellular organisms and the colonization of land CONCEPT 25.4 The rise and fall of groups of organisms reflect differences in speciation and extinction rates CONCEPT 25.5 Major changes in body form can result from changes in the sequences and regulation of developmental genes CONCEPT 25.6 Evolution is not goal oriented  UNIT 5  THE EVOLUTIONARY HISTORY OF BIOLOGICAL DIVERSITY 26  Phylogeny and the Tree of Life Investigating the Tree of Life CONCEPT 26.1 Phylogenies show evolutionary relationships CONCEPT 26.2 Phylogenies are inferred from morphological and molecular dataCONCEPT 26.3 Shared characters are used to construct phylogenetic trees CONCEPT 26.4 An organism’s evolutionary history is documented in its genome CONCEPT 26.5 Molecular clocks help track evolutionary time CONCEPT 26.6 Our understanding of the tree of life continues to change based on new data 27  Bacteria and Archaea Masters of Adaptation CONCEPT 27.1 Structural and functional adaptations contribute to prokaryotic success CONCEPT 27.2 Rapid reproduction, mutation, and genetic recombination promote genetic diversity in prokaryotes CONCEPT 27.3 Diverse nutritional and metabolic adaptations have evolved in prokaryotes CONCEPT 27.4 Prokaryotes have radiated into a diverse set of lineages CONCEPT 27.5 Prokaryotes play crucial roles in the biosphere CONCEPT 27.6 Prokaryotes have both beneficial and harmful impacts on humans 28  Protists Living Small CONCEPT 28.1 Most eukaryotes are single-celled organisms CONCEPT 28.2 Excavates include protists with modified mitochondria and protists with unique flagella CONCEPT 28.3 SAR is a highly diverse group of protists defined by DNA similarities CONCEPT 28.4 Red algae and green algae are the closest relatives of land plants CONCEPT 28.5 Unikonts include protists that are closely related to fungi and animals CONCEPT 28.6 Protists play key roles in ecological communities 29  Plant Diversity I: How Plants Colonized Land The Greening of Earth CONCEPT 29.1 Plants evolved from green algae CONCEPT 29.2 Mosses and other nonvascular plants have life cycles dominated by gametophytes CONCEPT 29.3 Ferns and other seedless vascular plants were the first plants to grow tall 30  Plant Diversity II: The Evolution of Seed Plants Transforming the World CONCEPT 30.1 Seeds and pollen grains are key adaptations for life on land CONCEPT 30.2 Gymnosperms bear “naked” seeds, typically on cones CONCEPT 30.3 The reproductive adaptations of angiosperms include flowers and fruits CONCEPT 30.4 Human welfare depends on seed plants 31  Fungi Mighty Mushrooms CONCEPT 31.1 Fungi are heterotrophs that feed by absorption CONCEPT 31.2 Fungi produce spores through sexual or asexual life cycles CONCEPT 31.3 The ancestor of fungi was an aquatic, single-celled, flagellated protist CONCEPT 31.4 Fungi have radiated into a diverse set of lineages CONCEPT 31.5 Fungi play key roles in nutrient cycling, ecological interactions, and human welfare 32  An Overview of Animal Diversity A Kingdom of Consumers CONCEPT 32.1 Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers CONCEPT 32.2 The history of animals spans more than half a billion years CONCEPT 32.3 Animals can be characterized by “body plans” CONCEPT 32.4 Views of animal phylogeny continue to be shaped by new molecular and morphological data 33  An Introduction to Invertebrates A Dragon Without a Backbone CONCEPT 33.1 Sponges are basal animals that lack tissues CONCEPT 33.2 Cnidarians are an ancient phylum of eumetazoans CONCEPT 33.3 Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms CONCEPT 33.4 Ecdysozoans are the most species-rich animal groupCONCEPT 33.5 Echinoderms and chordates are deuterostomes 34  The Origin and Evolution of Vertebrates Half a Billion Years of Backbones CONCEPT 34.1 Chordates have a notochord and a dorsal, hollow nerve cord CONCEPT 34.2 Vertebrates are chordates that have a backbone CONCEPT 34.3 Gnathostomes are vertebrates that have jaws CONCEPT 34.4 Tetrapods are gnathostomes that have limbs CONCEPT 34.5 Amniotes are tetrapods that have a terrestrially adapted egg CONCEPT 34.6 Mammals are amniotes that have hair and produce milk CONCEPT 34.7 Humans are mammals that have a large brain and bipedal locomotion  UNIT 6  PLANT FORM AND FUNCTION 35  Vascular Plant Structure, Growth, and Development Are Plants Computers? CONCEPT 35.1 Plants have a hierarchical organization consisting of organs, tissues, and cells CONCEPT 35.2 Different meristems generate new cells for primary and secondary growth CONCEPT 35.3 Primary growth lengthens roots and shoots CONCEPT 35.4 Secondary growth increases the diameter of stems and roots in woody plants CONCEPT 35.5 Growth, morphogenesis, and cell differentiation produce the plant body 36  Resource Acquisition and Transport in Vascular Plants A Whole Lot of Shaking Going On CONCEPT 36.1 Adaptations for acquiring resources were key steps in the evolution of vascular plants CONCEPT 36.2 Different mechanisms transport substances over short or long distances CONCEPT 36.3 Transpiration drives the transport of water and minerals from roots to shoots via the xylem CONCEPT 36.4 The rate of transpiration is regulated by stomata CONCEPT 36.5 Sugars are transported from sources to sinks via the phloem CONCEPT 36.6 The symplast is highly dynamic 37  Soil and Plant Nutrition The Corkscrew Carnivore CONCEPT 37.1 Soil contains a living, complex ecosystemCONCEPT 37.2 Plant roots absorb essential elements from the soilCONCEPT 37.3 Plant nutrition often involves relationships with other organisms 38  Angiosperm Reproduction and Biotechnology Flowers of Deceit CONCEPT 38.1 Flowers, double fertilization, and fruits are key features of the angiosperm life cycle CONCEPT 38.2 Flowering plants reproduce sexually, asexually, or both CONCEPT 38.3 People modify crops by breeding and genetic engineering 39  Plant Responses to Internal and External Signals Stimuli and a Stationary Life CONCEPT 39.1 Signal transduction pathways link signal reception to response CONCEPT 39.2 Plant hormones help coordinate growth, development, and responses to stimuli CONCEPT 39.3 Responses to light are critical for plant success CONCEPT 39.4 Plants respond to a wide variety of stimuli other than lightCONCEPT 39.5 Plants respond to attacks by pathogens and herbivores  UNIT 7  ANIMAL FORM AND FUNCTION 40  Basic Principles of Animal Form and Function Diverse Forms, Common Challenges CONCEPT 40.1 Animal form and function are correlated at all levels of organization CONCEPT 40.2 Feedback control maintains the internal environment in many animals CONCEPT 40.3 Homeostatic processes for thermoregulation involve form, function, and behavior CONCEPT 40.4 Energy requirements are related to animal size, activity, and environment 41  Animal Nutrition The Need to FeedCONCEPT 41.1 An animal’s diet must supply chemical energy, organic building blocks, and essential nutrients CONCEPT 41.2 Food processing involves ingestion, digestion, absorption, and elimination CONCEPT 41.3 Organs specialized for sequential stages of food processing form the mammalian digestive system CONCEPT 41.4 Evolutionary adaptations of vertebrate digestive systems correlate with diet CONCEPT 41.5 Feedback circuits regulate digestion, energy storage, and appetite 42  Circulation and Gas Exchange Trading Places CONCEPT 42.1 Circulatory systems link exchange surfaces with cells throughout the body CONCEPT 42.2 Coordinated cycles of heart contraction drive double circulation in mammals CONCEPT 42.3 Patterns of blood pressure and flow reflect the structure and arrangement of blood vessels CONCEPT 42.4 Blood components function in exchange, transport, and defense CONCEPT 42.5 Gas exchange occurs across specialized respiratory surfaces CONCEPT 42.6 Breathing ventilates the lungs CONCEPT 42.7 Adaptations for gas exchange include pigments that bind and transport gases 43  The Immune SystemRecognition and Response CONCEPT 43.1 In innate immunity, recognition and response rely on traits common to groups of pathogens CONCEPT 43.2 In adaptive immunity, receptors provide pathogen-specific recognition CONCEPT 43.3 Adaptive immunity defends against infection of body fluids and body cells CONCEPT 43.4 Disruptions in immune system function can elicit or exacerbate disease 44  Osmoregulation and ExcretionA Balancing Act CONCEPT 44.1 Osmoregulation balances the uptake and loss of water and solutes CONCEPT 44.2 An animal’s nitrogenous wastes reflect its phylogeny and habitat CONCEPT 44.3 Diverse excretory systems are variations on a tubular theme CONCEPT 44.4 The nephron is organized for stepwise processing of blood filtrate CONCEPT 44.5 Hormonal circuits link kidney function, water balance, and blood pressure 45  Hormones and the Endocrine System The Body’s Long-Distance Regulators CONCEPT 45.1 Hormones and other signaling molecules bind to target receptors, triggering specific response pathways CONCEPT 45.2 Feedback regulation and coordination with the nervous system are common in hormone pathways CONCEPT 45.3 Endocrine glands respond to diverse stimuli in regulating homeostasis, development, and behavior 46  Animal Reproduction Let Me Count the WaysCONCEPT 46.1 Both asexual and sexual reproduction occur in the animal kingdom CONCEPT 46.2 Fertilization depends on mechanisms that bring together sperm and eggs of the same species CONCEPT 46.3 Reproductive organs produce and transport gametes CONCEPT 46.4 The interplay of tropic and sex hormones regulates mammalian reproduction CONCEPT 46.5 In placental mammals, an embryo develops fully within the mother’s uterus 47  Animal Development A Body-Building Plan CONCEPT 47.1 Fertilization and cleavage initiate embryonic development CONCEPT 47.2 Morphogenesis in animals involves specific changes in cell shape, position, and survival CONCEPT 47.3 Cytoplasmic determinants and inductive signals regulate cell fate 48  Neurons, Synapses, and Signaling Lines of Communication CONCEPT 48.1 Neuron structure and organization reflect function in information transfer CONCEPT 48.2 Ion pumps and ion channels establish the resting potential of a neuron CONCEPT 48.3 Action potentials are the signals conducted by axons CONCEPT 48.4 Neurons communicate with other cells at synapses 49  Nervous Systems Command and Control Center CONCEPT 49.1 Nervous systems consist of circuits of neurons and supporting cells CONCEPT 49.2 The vertebrate brain is regionally specialized CONCEPT 49.3 The cerebral cortex controls voluntary movement and cognitive functions CONCEPT 49.4 Changes in synaptic connections underlie memory and learning CONCEPT 49.5 Many nervous system disorders can be explained in molecular terms 50  Sensory and Motor Mechanisms Sense and Sensibility CONCEPT 50.1 Sensory receptors transduce stimulus energy and transmit signals to the central nervous system CONCEPT 50.2 In hearing and equilibrium, mechanoreceptors detect moving fluid or settling particles CONCEPT 50.3 The diverse visual receptors of animals depend on light-absorbing pigmentsCONCEPT 50.4 The senses of taste and smell rely on similar sets of sensory receptors CONCEPT 50.5 The physical interaction of protein filaments is required for muscle functionCONCEPT 50.6 Skeletal systems transform muscle contraction into locomotion 51  Animal Behavior The How and Why of Animal Activity CONCEPT 51.1 Discrete sensory inputs can stimulate both simple and complex behaviors CONCEPT 51.2 Learning establishes specific links between experience and behavior CONCEPT 51.3 Selection for individual survival and reproductive success can explain diverse behaviors CONCEPT 51.4 Genetic analyses and the concept of inclusive fitness provide a basis for studying the evolution of behavior  UNIT 8  ECOLOGY 52  An Introduction to Ecology and the Biosphere Discovering Ecology CONCEPT 52.1 Earth’s climate varies by latitude and season and is changing rapidly CONCEPT 52.2 The distribution of terrestrial biomes is controlled by climate and disturbance CONCEPT 52.3 Aquatic biomes are diverse and dynamic systems that cover most of EarthCONCEPT 52.4 Interactions between organisms and the environment limit the distribution of species CONCEPT 52.5Ecological change and evolution affect one another over long and short periods of time53  Population EcologyTurtle Tracks CONCEPT 53.1 Biotic and abiotic factors affectpopulation density, dispersion, and demographics CONCEPT 53.2 The exponential model describes population growth in an idealized, unlimited environment CONCEPT 53.3 The logistic model describes how a population grows more slowly as it nears its carrying capacity CONCEPT 53.4 Life history traits are products of natural selection CONCEPT 53.5 Density-dependent factors regulate population growthCONCEPT 53.6 The human population is no longer growing exponentially but is still increasing rapidly 54  Community Ecology Communities in Motion CONCEPT 54.1 Community interactions are classified by whether they help, harm, or have no effect on the species involved CONCEPT 54.2 Diversity and trophic structure characterize biological communities CONCEPT 54.3 Disturbance influences species diversity and composition CONCEPT 54.4 Biogeographic factors affect community diversity CONCEPT 54.5 Pathogens alter community structure locally and globally 55  Ecosystems and Restoration Ecology Transformed to Tundra CONCEPT 55.1 Physical laws govern energy flow and chemical cycling in ecosystems CONCEPT 55.2 Energy and other limiting factors control primary production in ecosystems CONCEPT 55.3 Energy transfer between trophic levels is typically only 10% efficient CONCEPT 55.4 Biological and geochemical processes cycle nutrients and water in ecosystems CONCEPT 55.5 Restoration ecologists return degraded ecosystems to a more natural state 56  Conservation Biology and Global ChangePsychedelic Treasure CONCEPT 56.1 Human activities threaten Earth’s biodiversity CONCEPT 56.2 Population conservation focuses on population size, genetic diversity, and critical habitat CONCEPT 56.3 Landscape and regional conservation help sustain biodiversity CONCEPT 56.4 Earth is changing rapidly as a result of human actionsCONCEPT 56.5 Sustainable development can improve human lives while conserving biodiversity