Campbell Biology Concepts and Connections TENTH EDITION Global Edition 2022

Cover Brief Contents Title Page Copyright About the Authors Visual Walkthrough Open up the World of Biology Build Science Literacy Skills Visualize Tough Topics and Develop Understanding (I) Visualize Tough Topics and Develop Understanding (II) Encourage Focus on Key Concepts and Active Learning Dynamic Digital Resources Bring Biology to Life Everything Students and Instructors Need to Succeed in Mastering Biology Engage in Biology Anytime, Anywhere with Mastering Biology (I) Engage in Biology Anytime, Anywhere with Mastering Biology (II) Preface Organization and New Content Acknowledgments Reviewers Acknowledgments for the Global Edition Detailed Contents Chapter 1: Biology: Exploring Life Biology: The Scientific Study of Life 1.1 Biology is the scientific study of life 1.2 Biologists arrange the diversity of life into three domains 1.3 Visualizing The Concept In life’s hierarchy of organization, new properties emerge at each level The Process of Science 1.4 What is science? 1.5 Hypotheses can be tested using controlled experiments 1.6 Scientific Thinking Hypotheses can be tested using observational data 1.7 The process of science is repetitive, nonlinear, and collaborative 1.8 Connection Biology, technology, and society are connected in important ways Five Unifying Themes in Biology 1.9 Theme: Evolution is the core theme of biology 1.10 Evolution Connection Evolution is connected to our everyday lives 1.11 Theme: Life depends on the flow of information 1.12 Theme: Structure and function are related 1.13 Theme: Life depends on the transfer and transformation of energy and matter 1.14 Theme: Life depends on interactions within and between systems Chapter Review Unit I: The Life of the Cell Chapter 2: The Chemical Basis of Life Elements, Atoms, and Compounds 2.1 Organisms are composed of elements, usually combined into compounds 2.2 Connection Trace elements are common additives to food and water 2.3 Atoms consist of protons, neutrons, and electrons 2.4 Connection Radioactive isotopes can help or harm us Chemical Bonds 2.5 The distribution of electrons determines an atom’s chemical properties 2.6 Visualizing The Concept Covalent bonds join atoms into molecules through electron sharing 2.7 Ionic bonds are attractions between ions of opposite charge 2.8 Hydrogen bonds are weak bonds important in the chemistry of life 2.9 Chemical reactions make and break chemical bonds Water’s Life-Supporting Properties 2.10 Hydrogen bonds make liquid water cohesive 2.11 Water’s hydrogen bonds moderate temperature 2.12 Ice floats because it is less dense than liquid water 2.13 Water is the solvent of life 2.14 The chemistry of life is sensitive to acidic and basic conditions 2.15 Scientific Thinking Scientists study the effects of rising atmospheric CO2 on coral reef ecosystems 2.16 Evolution Connection The search for extraterrestrial life centers on the search for water Chapter Review Chapter 3: The Molecules of Cells Introduction to Organic Compounds 3.1 Life’s molecular diversity is based on the properties of carbon 3.2 A few chemical groups are key to the functioning of biological molecules 3.3 Cells make large molecules from a limited set of small molecules Carbohydrates 3.4 Monosaccharides are the simplest carbohydrates 3.5 Two monosaccharides are linked to form a disaccharide 3.6 Connection Are we eating too much sugar? 3.7 Polysaccharides are long chains of sugar units Lipids 3.8 Fats are lipids that are mostly energy-storage molecules 3.9 Scientific Thinking Scientific studies document the health risks of trans fats 3.10 Phospholipids and steroids are important lipids with a variety of functions 3.11 Connection Anabolic steroids pose health risks Proteins 3.12 Proteins have a wide range of functions and structures 3.13 Proteins are made from amino acids linked by peptide bonds 3.14 Visualizing The Concept A protein’s functional shape results from four levels of structure Nucleic Acids 3.15 The nucleic acids DNA and RNA are information-rich polymers of nucleotides 3.16 Evolution Connection Lactose tolerance is a recent event in human evolution Chapter Review Chapter 4: A Tour of the Cell Introduction to the Cell 4.1 Microscopes reveal the world of the cell 4.2 The small size of cells relates to the need to exchange materials across the plasma membrane 4.3 Prokaryotic cells are structurally simpler than eukaryotic cells 4.4 Eukaryotic cells are partitioned into functional compartments The Nucleus and Ribosomes 4.5 The nucleus contains the cell’s genetic instructions 4.6 Ribosomes make proteins for use in the cell and for export The Endomembrane System 4.7 Many organelles are connected in the endomembrane system 4.8 The endoplasmic reticulum is a biosynthetic workshop 4.9 The Golgi apparatus modifies, sorts, and ships cell products 4.10 Lysosomes are digestive compartments within a cell 4.11 Vacuoles function in the general maintenance of the cell 4.12 A review of the structures involved in manufacturing and breakdown Energy-Converting Organelles 4.13 Mitochondria harvest chemical energy from food 4.14 Chloroplasts convert solar energy to chemical energy 4.15 Evolution Connection Mitochondria and chloroplasts evolved by endosymbiosis The Cytoskeleton and Cell Surfaces 4.16 The cell’s internal skeleton helps organize its structure and activities 4.17 Scientific Thinking Scientists discovered the cytoskeleton using the tools of biochemistry and microscopy 4.18 Cilia and flagella move when microtubules bend 4.19 The extracellular matrix of animal cells functions in support and regulation 4.20 Three types of cell junctions are found in animal tissues 4.21 Cell walls enclose and support plant cells 4.22 Review: Eukaryotic cell structures can be grouped on the basis of four main functions Chapter Review Chapter 5: The Working Cell Membrane Structure and Function 5.1 Visualizing The Concept Membranes are fluid mosaics of lipids and proteins with many functions 5.2 Evolution Connection The spontaneous formation of membranes was a critical step in the origin of life 5.3 Passive transport is diffusion across a membrane with no energy investment 5.4 Osmosis is the diffusion of water across a membrane 5.5 Water balance between cells and their surroundings is crucial to organisms 5.6 Transport proteins can facilitate diffusion across membranes 5.7 Scientific Thinking Research on another membrane protein led to the discovery of aquaporins 5.8 Cells expend energy in the active transport of a solute 5.9 Exocytosis and endocytosis transport large molecules across membranes Energy and the Cell 5.10 Cells transform energy and matter as they perform work 5.11 Chemical reactions either release or store energy 5.12 ATP drives cellular work by coupling exergonic and endergonic reactions How Enzymes Function 5.13 Enzymes speed up the cell’s chemical reactions by lowering energy barriers 5.14 A specific enzyme catalyzes each cellular reaction 5.15 Enzyme inhibition can regulate enzyme activity in a cell 5.16 Connection Many drugs, pesticides, and poisons are enzyme inhibitors Chapter Review Chapter 6: How Cells Harvest Chemical Energy Cellular Respiration: Aerobic Harvesting of Energy 6.1 Photosynthesis and cellular respiration provide energy for life 6.2 Breathing supplies O2 for use in cellular respiration and removes CO2 6.3 Cellular respiration banks energy in ATP molecules 6.4 Connection The human body uses energy from ATP for all its activities 6.5 Cells capture energy from electrons “falling” from organic fuels to oxygen Stages of Cellular Respiration 6.6 Overview: Cellular respiration occurs in three main stages 6.7 Stage 1: Glycolysis harvests chemical energy by oxidizing glucose to pyruvate 6.8 Multiple reactions in glycolysis split glucose into two molecules 6.9 Stage 2: The citric acid cycle completes the energy-yielding oxidation of organic molecules 6.10 The multiple reactions of the citric acid cycle finish off the dismantling of glucose 6.11 Visualizing The Concept Stage 3: Most ATP production occurs by oxidative phosphorylation 6.12 Scientific Thinking Scientists have discovered heat-producing, calorie-burning brown fat in adults 6.13 Review: Each molecule of glucose yields many molecules of ATP Fermentation: Anaerobic Harvesting of Energy 6.14 Fermentation enables cells to produce ATP without oxygen 6.15 Evolution Connection Glycolysis evolved early in the history of life on Earth Connections Between Metabolic Pathways 6.16 Cells use many kinds of organic molecules as fuel for cellular respiration 6.17 Organic molecules from food provide raw materials for biosynthesis Chapter Review Chapter 7: Photosynthesis: Using Light to Make Food An Introduction to Photosynthesis 7.1 Photosynthesis powers most life on Earth 7.2 Photosynthesis occurs in chloroplasts in plant cells 7.3 Scientists traced the process of photosynthesis using isotopes 7.4 Photosynthesis is a redox process 7.5 Photosynthesis occurs in two stages, which are linked by ATP and NADPH The Light Reactions: Converting Solar Energy to Chemical Energy 7.6 Visible radiation absorbed by pigments drives the light reactions 7.7 Photosystems capture solar energy 7.8 Two photosystems connected by an electron transport chain convert light energy to the chemical energy of ATP and NADPH 7.9 Visualizing The Concept The light reactions take place within the thylakoid membranes The Calvin Cycle: Reducing CO2 to Sugar 7.10 ATP and NADPH power sugar synthesis in the Calvin cycle 7.11 Evolution Connection Other methods of carbon fixation have evolved in hot, dry climates The Global Significance of Photosynthesis 7.12 Photosynthesis provides food and O2 for almost all living organisms 7.13 Scientific Thinking Rising atmospheric levels of carbon dioxide may affect plants in various ways 7.14 Connection Reducing both fossil fuel use and deforestation may moderate climate change Chapter Review Unit II: Cellular Reproduction and Genetics Chapter 8: The Cellular Basis of Reproduction and Inheritance Cell Division and Reproduction 8.1 Cell division plays many important roles in the lives of organisms 8.2 Prokaryotes reproduce by binary fission The Eukaryotic Cell Cycle and Mitosis 8.3 The large, complex chromosomes of eukaryotes duplicate with each cell division 8.4 The cell cycle includes growth and division phases 8.5 Cell division is a continuum of dynamic changes 8.6 Cytokinesis differs for plant and animal cells 8.7 The rate of cell division is affected by environmental factors 8.8 Growth factors signal the cell cycle control system 8.9 Connection Growing out of control, cancer cells produce malignant tumors 8.10 Scientific Thinking The best cancer treatment may vary by individual Meiosis and Crossing Over 8.11 Chromosomes are matched in homologous pairs 8.12 Gametes have a single set of chromosomes 8.13 Meiosis reduces the chromosome number from diploid to haploid 8.14 Visualizing The Concept Mitosis and meiosis have important similarities and differences 8.15 Independent orientation of chromosomes in meiosis and random fertilization lead to varied offspring 8.16 Homologous chromosomes may carry different versions of genes 8.17 Visualizing The Concept Crossing over further increases genetic variability Alterations of Chromosome Number and Structure 8.18 Accidents during meiosis can alter chromosome number 8.19 A karyotype is a photographic inventory of an individual’s chromosomes 8.20 Connection An extra copy of chromosome 21 causes Down syndrome 8.21 Connection Abnormal numbers of sex chromosomes do not usually affect survival 8.22 Evolution Connection New species can arise from errors in cell division 8.23 Connection Alterations of chromosome structure can cause birth defects and cancer Chapter Review Chapter 9: Patterns of Inheritance Mendel’s Laws 9.1 The study of genetics has ancient roots 9.2 The science of genetics began in an abbey garden 9.3 Mendel’s law of segregation describes the inheritance of a single character 9.4 Homologous chromosomes bear the alleles for each character 9.5 The law of independent assortment is revealed by tracking two characters at once 9.6 Geneticists can use a testcross to determine unknown genotypes 9.7 Mendel’s laws reflect the rules of probability 9.8 Visualizing The Concept Genetic traits in humans can be tracked through family pedigrees 9.9 Connection Many inherited traits in humans are controlled by a single gene 9.10 Connection New technologies can provide insight into one’s genetic legacy Variations on Mendel’s Laws 9.11 Incomplete dominance results in intermediate phenotypes 9.12 Many genes have more than two alleles that may be codominant 9.13 A single gene may affect many phenotypic characters 9.14 A single character may be influenced by many genes 9.15 The environment affects many characters The Chromosomal Basis of Inheritance 9.16 Chromosome behavior accounts for Mendel’s laws 9.17 Scientific Thinking Genes on the same chromosome tend to be inherited together 9.18 Crossing over produces new combinations of alleles 9.19 Geneticists use crossover data to map genes Sex Chromosomes and Sex-Linked Genes 9.20 Chromosomes determine sex in many species 9.21 Sex-linked genes exhibit a unique pattern of inheritance 9.22 Connection Human sex-linked disorders affect mostly males 9.23 Evolution Connection The Y chromosome provides clues about human male evolution Chapter Review Chapter 10: Molecular Biology of the Gene The Structure of the Genetic Material 10.1 Scientific Thinking Experiments showed that DNA is the genetic material 10.2 DNA and RNA are polymers of nucleotides 10.3 DNA is a double-stranded helix DNA Replication 10.4 DNA replication depends on specific base pairing 10.5 DNA replication proceeds in two directions at many sites simultaneously The Flow of Genetic Information from DNA to RNA to Protein 10.6 Genes control phenotypic traits through the expression of proteins 10.7 Genetic information written in codons is translated into amino acid sequences 10.8 The genetic code dictates how codons are translated into amino acids 10.9 Visualizing The Concept Transcription produces genetic messages in the form of RNA 10.10 Eukaryotic RNA is processed before leaving the nucleus as mRNA 10.11 Transfer RNA molecules serve as interpreters during translation 10.12 Ribosomes build polypeptides 10.13 An initiation codon marks the start of an mRNA message 10.14 Elongation adds amino acids to the polypeptide chain until a stop codon terminates translation 10.15 Review: The flow of genetic information in the cell is DNA → RNA → protein 10.16 Mutations can affect genes The Genetics of Viruses and Bacteria 10.17 Viral DNA may become part of the host chromosome 10.18 Connection Many viruses cause disease in animals and plants 10.19 Evolution Connection Emerging viruses threaten human health 10.20 The AIDS virus makes DNA on an RNA template 10.21 Prions are infectious proteins 10.22 Bacteria can transfer DNA in three ways 10.23 Bacterial plasmids can serve as carriers for gene transfer Chapter Review Chapter 11: How Genes Are Controlled Control of Gene Expression 11.1 Proteins interacting with DNA turn prokaryotic genes on or off in response to environmental changes 11.2 Chromosome structure and chemical modifications can affect gene expression 11.3 Complex assemblies of proteins control eukaryotic transcription 11.4 Eukaryotic RNA may be spliced in more than one way 11.5 Later stages of gene expression are also subject to regulation 11.6 Noncoding RNAs play multiple roles in controlling gene expression 11.7 Visualizing The Concept Multiple mechanisms regulate gene expression in eukaryotes 11.8 Fruit fly development provides an opportunity to examine gene expression 11.9 Connection Researchers can monitor the expression of specific genes 11.10 Cells respond to their neighboring cells with changes in gene expression 11.11 Evolution Connection Cell-signaling systems appeared early in the evolution of life Cloning of Plants and Animals 11.12 Plant cloning shows that differentiated cells may retain all of their genetic potential 11.13 Scientific Thinking Biologists can clone animals via nuclear transplantation 11.14 Connection Therapeutic cloning can produce stem cells with great medical potential The Genetic Basis of Cancer 11.15 Cancer results from mutations in genes that control cell division 11.16 Multiple genetic changes underlie the development of cancer 11.17 Faulty proteins can interfere with normal signal transduction pathways 11.18 Connection Lifestyle choices can reduce the risk of cancer Chapter Review Chapter 12: DNA Technology and Genomics Gene Cloning and Editing 12.1 Genes can be cloned in recombinant plasmids 12.2 Visualizing The Concept Enzymes are used to “cut and paste” DNA 12.3 Nucleic acid probes can label specific DNA segments 12.4 Reverse transcriptase can help make genes for cloning 12.5 New techniques allow a specific gene to be edited Genetically Modified Organisms 12.6 Recombinant cells and organisms can mass-produce gene products 12.7 Connection DNA technology has changed the pharmaceutical industry and medicine 12.8 Connection Genetically modified organisms are transforming agriculture 12.9 Scientific Thinking The use of genetically modified organisms raises questions and concerns 12.10 Connection Gene therapy may someday help treat a variety of diseases DNA Profiling 12.11 The analysis of genetic markers can produce a DNA profile 12.12 The PCR method is used to amplify DNA sequences 12.13 Gel electrophoresis sorts DNA molecules by size 12.14 Short tandem repeat analysis is used for DNA profiling 12.15 Connection DNA profiling has provided evidence in many forensic investigations Genomics and Bioinformatics 12.16 Small segments of DNA can be sequenced directly 12.17 Genomics is the scientific study of whole genomes 12.18 Connection The Human Genome Project revealed that most of the human genome does not consist of genes 12.19 The whole-genome shotgun method of sequencing a genome can provide a wealth of data quickly 12.20 The field of bioinformatics is expanding our understanding of genomes 12.21 Evolution Connection Genomes hold clues to human evolution Chapter Review Unit III: Concepts of Evolution Chapter 13: How Populations Evolve Darwin’s Theory of Evolution 13.1 A sea voyage helped Darwin frame his theory of evolution 13.2 The study of fossils provides strong evidence for evolution 13.3 Scientific Thinking Fossils of transitional forms support Darwin’s theory of evolution 13.4 Homologies provide strong evidence for evolution 13.5 Homologies indicate patterns of descent that can be shown on an evolutionary tree 13.6 Darwin proposed natural selection as the mechanism of evolution 13.7 Scientists can observe natural selection in action The Evolution of Populations 13.8 Mutation and sexual reproduction produce the genetic variation that makes evolution possible 13.9 Evolution occurs within populations 13.10 The Hardy-Weinberg equation can test whether a population is evolving 13.11 Connection The Hardy-Weinberg equation is useful in public health science Mechanisms of Microevolution 13.12 Natural selection, genetic drift, and gene flow can cause microevolution 13.13 Natural selection is the only mechanism that consistently leads to adaptive evolution 13.14 Visualizing The Concept Natural selection can alter variation in a population in three ways 13.15 Sexual selection may lead to phenotypic differences between males and females 13.16 Evolution Connection The evolution of drugresistant microorganisms is a serious public health concern 13.17 Diploidy and balancing selection preserve genetic variation 13.18 Natural selection cannot fashion perfect organisms Chapter Review Chapter 14: The Origin of Species Defining Species 14.1 The origin of species is the source of biological diversity 14.2 There are several ways to define a species 14.3 Visualizing The Concept Reproductive barriers keep species separate Mechanisms of Speciation 14.4 In allopatric speciation, geographic isolation leads to speciation 14.5 Reproductive barriers can evolve as populations diverge 14.6 Sympatric speciation takes place without geographic isolation 14.7 Scientific Thinking Sexual selection can lead to speciation 14.8 Isolated islands are often showcases of speciation 14.9 Evolution Connection Long-term field studies document evolution in Darwin’s finches 14.10 Hybrid zones provide opportunities to study reproductive isolation 14.11 Speciation can occur rapidly or slowly Chapter Review Chapter 15: Tracing Evolutionary History Early Earth and the Origin of Life 15.1 Conditions on early Earth made the origin of life possible 15.2 Scientific Thinking Experiments show that the abiotic synthesis of organic molecules is possible 15.3 Stages in the origin of the first cells probably included the formation of polymers, protocells, and self-replicating RNA Major Events in the History of Life 15.4 The origins of single-celled and multicellular organisms and the colonization of land were key events in life’s history 15.5 The actual ages of rocks and fossils mark geologic time 15.6 The fossil record documents the history of life Mechanisms of Macroevolution 15.7 Continental drift has played a major role in macroevolution 15.8 Connection Plate tectonics may imperil human life 15.9 Five mass extinctions have altered the course of evolution 15.10 Adaptive radiations have increased the diversity of life 15.11 Genes that control development play a major role in evolution 15.12 Evolution Connection Novel traits may arise in several ways 15.13 Evolutionary trends do not mean that evolution is goal directed Phylogeny and the Tree of Life 15.14 Taxonomy names and classifies the diversity of life 15.15 Phylogenies based on homologies reflect evolutionary history 15.16 Shared characters are used to construct phylogenetic trees 15.17 An organism’s evolutionary history is documented in its genome 15.18 Molecular clocks help track evolutionary time 15.19 Constructing the tree of life is a work in progress Chapter Review Unit IV: The Evolution of Biological Diversity Chapter 16: Microbial Life: Prokaryotes and Protists Prokaryotes 16.1 Prokaryotes are diverse and widespread 16.2 External features contribute to the success of prokaryotes 16.3 Populations of prokaryotes can adapt rapidly to changes in the environment 16.4 Prokaryotes have unparalleled nutritional diversity 16.5 Connection Biofilms are complex associations of microbes 16.6 Connection Prokaryotes help clean up the environment 16.7 Bacteria and archaea are the two main branches of prokaryotic evolution 16.8 Archaea thrive in extreme environments—and in other habitats 16.9 Bacteria include a diverse assemblage of prokaryotes 16.10 Connection Some bacteria cause disease 16.11 Scientific Thinking Stomach microbiota affect health and disease Protists 16.12 Protists are an extremely diverse assortment of eukaryotes 16.13 Protist diversity is organized in supergroups 16.14 The SAR supergroup represents the range of protist diversity 16.15 Connection Can algae provide a renewable source of energy? 16.16 Some excavates have modified mitochondria 16.17 Unikonts include protists that are closely related to fungi and animals 16.18 Archaeplastids include red algae, green algae, and land plants 16.19 Evolution Connection Multicellularity evolved several times in eukaryotes Chapter Review Chapter 17: The Evolution of Plant and Fungal Diversity Plant Evolution and Diversity 17.1 Plants have adaptations for life on land 17.2 Plant diversity reflects the evolutionary history of the plant kingdom Alternation of Generations and Plant Life Cycles 17.3 Visualizing The Concept Haploid and diploid generations alternate in plant life cycles 17.4 Seedless vascular plants dominated vast “coal forests” 17.5 Pollen and seeds are key adaptations for life on land 17.6 The flower is the centerpiece of angiosperm reproduction 17.7 The angiosperm plant is a sporophyte with gametophytes in its flowers 17.8 The structure of a fruit reflects its function in seed dispersal 17.9 Connection Angiosperms sustain us—and add spice to our diets 17.10 Evolution Connection Pollination by animals has influenced angiosperm evolution 17.11 Connection Plant diversity is vital to the future of the world’s food supply Diversity of Fungi 17.12 Fungi absorb food after digesting it outside their bodies 17.13 Fungi produce spores in both asexual and sexual life cycles 17.14 Fungi are classified into five groups 17.15 Connection Fungi have enormous ecological benefits 17.16 Connection Fungi have many practical uses 17.17 Lichens are symbiotic associations of fungi and photosynthetic organisms 17.18 Scientific Thinking Mycorrhizae may have helped plants colonize land 17.19 Connection Parasitic fungi harm plants and animals Chapter Review Chapter 18: The Evolution of Invertebrate Diversity Animal Evolution and Diversity 18.1 What is an animal? 18.2 Animal diversification began more than half a billion years ago 18.3 Visualizing The Concept Animals can be characterized by basic features of their “body plan” 18.4 Body plans and molecular comparisons of animals can be used to build phylogenetic trees Invertebrate Diversity 18.5 Sponges have a relatively simple, porous body 18.6 Cnidarians are radial animals with tentacles and stinging cells 18.7 Flatworms are the simplest bilateral animals 18.8 Nematodes have a body cavity and a complete digestive tract 18.9 Diverse molluscs are variations on a common body plan 18.10 Annelids are segmented worms 18.11 Arthropods are segmented animals with jointed appendages and an exoskeleton 18.12 Evolution Connection Insects are the most successful group of animals 18.13 Scientific Thinking The genes that build animal bodies are ancient 18.14 Echinoderms have spiny skin, an endoskeleton, and a water vascular system for movement 18.15 Our own phylum, Chordata, is distinguished by four features 18.16 Connection Invertebrate diversity is a valuable but threatened resource Chapter Review Chapter 19: The Evolution of Vertebrate Diversity Vertebrate Evolution and Diversity 19.1 Shared derived characters define the major clades of chordates 19.2 Hagfishes and lampreys lack hinged jaws 19.3 Jawed vertebrates with gills and paired fins include sharks, ray-finned fishes, and lobe-finned fishes 19.4 Evolution Connection New fossil discoveries are filling in the gaps of tetrapod evolution 19.5 Amphibians are tetrapods—vertebrates with two pairs of limbs 19.6 Reptiles are amniotes—tetrapods with a terrestrially adapted egg 19.7 Birds are feathered reptiles with adaptations for flight 19.8 Mammals are amniotes that have hair and produce milk Primate Diversity 19.9 Visualizing The Concept Many primate characters are adaptations to life in the trees 19.10 The human story begins with our primate heritage Hominin Evolution 19.11 The hominin branch of the primate tree includes species that coexisted 19.12 Australopiths were bipedal and had small brains 19.13 Larger brains mark the evolution of Homo 19.14 From origins in Africa, Homo sapiens spread around the world 19.15 Scientific Thinking New discoveries raise new questions about the history of hominins 19.16 Evolution Connection Human skin color reflects adaptations to varying amounts of sunlight 19.17 Connection Our knowledge of animal diversity is far from complete Chapter Review Unit V: Animals: Form and Function Chapter 20: Unifying Concepts of Animal Structure and Function Structure and Function in Animal Tissues 20.1 Evolution Connection An animal’s form is not the perfect design 20.2 Structure fits function at all levels of organization in the animal body 20.3 Tissues are groups of cells with a common structure and function 20.4 Epithelial tissue covers the body and lines its organs and cavities 20.5 Connective tissue binds and supports other tissues 20.6 Muscle tissue functions in movement 20.7 Nervous tissue forms a communication network Organs and Organ Systems 20.8 Organs are made up of tissues 20.9 Connection Bioengineers are learning to produce organs for transplants 20.10 Organ systems work together to perform life’s functions 20.11 The integumentary system protects the body 20.12 Scientific Thinking Well-designed experiments help answer scientific questions External Exchange and Internal Regulation 20.13 Structural adaptations enhance exchange with the environment 20.14 Animals regulate their internal environment 20.15 Homeostasis depends on negative feedback Chapter Review Chapter 21: Nutrition and Digestion Obtaining and Processing Food 21.1 Animals obtain and ingest their food in a variety of ways 21.2 Overview: Food processing occurs in four stages 21.3 Digestion occurs in specialized compartments The Human Digestive System 21.4 The human digestive system consists of an alimentary canal and accessory organs 21.5 Digestion begins in the oral cavity 21.6 After swallowing, peristalsis moves food through the esophagus to the stomach 21.7 Connection The Heimlich maneuver can save lives 21.8 The stomach stores food and breaks it down with acid and enzymes 21.9 Connection Digestive ailments include acid reflux and gastric ulcers 21.10 The small intestine is the major organ of chemical digestion and nutrient absorption 21.11 The liver processes and detoxifies blood from the intestines 21.12 The large intestine reclaims water and compacts the feces 21.13 Evolution Connection Evolutionary adaptations of vertebrate digestive systems relate to diet Nutrition 21.14 An animal’s diet must provide sufficient energy 21.15 An animal’s diet must supply essential nutrients 21.16 A proper human diet must include sufficient vitamins and minerals 21.17 Connection Food labels provide nutritional information 21.18 Connection Dietary deficiencies can have a number of causes 21.19 Evolution Connection The human health problem of obesity may reflect our evolutionary past 21.20 Scientific Thinking Scientists use a variety of methods