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Contents<br/>Chemical Biology<br/>Part I The Origin of Living Things<br/>1<br/>The Science of Biology <br/>Science is the process of testing ideas against observation. Darwin <br/>developed his ideas about evolution by testing them against a wealth of <br/>observation. In this text science will provide the framework for your <br/>exploration of life.<br/> 1.1 Biology is the science of life.<br/> 1.2 Scientists form generalizations from observations.<br/> 1.3 Darwin's theory of evolution illustrates how science works.<br/> 1.4 This book is organized to help you learn biology.<br/>2<br/>The Nature of Molecules <br/>Organisms are chemical machines, and to understand them we must first <br/>learn a little chemistry. We first explore how atoms are linked together <br/>into molecules. The character of the water molecule in large measure <br/>determines what organisms are like.<br/> 2.1 Atoms are nature's building material.<br/> 2.2 The atoms of living things are among the smallest.<br/> 2.3 Chemical bonds hold molecules together.<br/> 2.4 Water is the cradle of life.<br/>3<br/>The Chemical Building Blocks of Life <br/>The four kinds of large macromolecules that are the building blocks of <br/>organisms are each built up of long chains of carbon atoms. In each, the <br/>macromolecule is assembled as a long chain of subunits, like pearls in a <br/>necklace or cars of a railway train.<br/> 3.1 Molecules are the building blocks of life.<br/> 3.2 Proteins perform the chemistry of the cell.<br/> 3.3 Nucleic acids store and transfer genetic information.<br/> 3.4 Lipids make membranes and store energy.<br/> 3.5 Carbohydrates store energy and provide building materials.<br/>4<br/>The Origin and Early History of Life <br/>Little is known about how life originated on earth. If it originated <br/>spontaneously, as most biologists surmise, then it must have evolved <br/>very quickly, as microfossils of bacteria are found in rocks formed soon <br/>after earth's surface cooled.<br/> 4.1 All living things share key characteristics.<br/> 4.2 There are many ideas about the origin of life.<br/> 4.3 The first cells had little internal structure.<br/> 4.4 The first eukaryotic cells were larger and more complex than <br/>bacteria. <br/>Cell Biology<br/>Part II Biology of the Cell<br/>5<br/>Cell Structure <br/>Bacterial cells have little internal organization, while the cells of <br/>eukaryotes are subdivided by internal membranes into numerous <br/>compartments with different functions. Compartmentalization is the <br/>hallmark of the eukaryotic cell.<br/> 5.1 All organisms are composed of cells.<br/> 5.2 Eukaryotic cells are far more complex than bacterial cells.<br/> 5.3 Take a tour of a eukaryotic cell.<br/> 5.4 Symbiosis played a key role in the origin of some eukaryotic <br/>organelles.<br/>6<br/>Membranes <br/>Every cell is encased within a thin membrane that separates it from its <br/>environment. The membrane is a mosaic of proteins floating on a sheet of <br/>lipid that provide channels into the cell for both molecules and <br/>information. <br/> 6.1 Biological membranes are fluid layers of lipid.<br/> 6.2 Proteins embedded within the plasma membrane determine its <br/>character.<br/> 6.3 Passive transport across membranes moves down the <br/>concentration gradient.<br/> 6.4 Bulk transport utilizes endocytosis.<br/> 6.5 Active transport across membranes is powered by energy from <br/>ATP.<br/>7<br/>Cell-Cell Interactions <br/>Cells receive molecular signals with protein receptors on or within the <br/>plasma membrane. The information passes into the cell interior as a <br/>cascade of interactions that greatly amplify the strength of the <br/>original signal.<br/> 7.1 Cells signal one another with chemicals.<br/> 7.2 Proteins in the cell and on its surface receive signals from <br/>other cells.<br/> 7.3 Follow the journey of information into the cell.<br/> 7.4 Cell surface proteins mediate cell-cell interactions.<br/>Cell Biology<br/>Part III Energetics<br/>8<br/>Energy and Metabolism <br/>Organisms use proteins called enzymes to facilitate chemical reactions. <br/>When the products of a reaction contain more energy than the starting <br/>materials, the extra amount is supplied by ATP, the energy currency of <br/>the cell.<br/> 8.1 The laws of thermodynamics describe how energy changes.<br/> 8.2 Enzymes are biological catalysts.<br/> 8.3 ATP is the energy currency of life.<br/> 8.4 Metabolism is the chemical life of a cell.<br/>9<br/>How Cells Harvest Energy <br/>Cells harvest chemical energy from the C-H chemical bonds of food <br/>molecules. Some of this energy is captured by rearranging chemical <br/>bonds, but most of it is harvested by oxidation, in reactions where the <br/>electrons of C-H bonds are used to reduce atmospheric oxygen to water.<br/> 9.1 Cells harvest the energy in chemical bonds.<br/> 9.2 Cellular respiration oxidizes food molecules.<br/> 9.3 Catabolism of proteins and fats can yield considerable <br/>energy.<br/> 9.4 Cells can metabolize food without oxygen.<br/>10<br/>Photosynthesis <br/>Photosynthesis is the reverse of respiration, the energy of sunlight <br/>being harnessed to reduce carbon dioxide with electrons obtained from <br/>water, leaving oxygen gas as the by-product. All organic molecules are <br/>the direct or indirect products of photosynthetic carbon fixation.<br/> 10.1 What is photosynthesis?<br/> 10.2 Learning about photosynthesis: An experimental journey.<br/> 10.3 Pigments capture energy from sunlight.<br/> 10.4 Cells use the energy and reducing power captured by the <br/>light reactions to make organic molecules. <br/> Genetics<br/> Part IV Reproduction and Heredity<br/>11<br/>How Cells Divide <br/>The division of a eukaryotic cell involves a complex and carefully <br/>orchestrated division of chromosome copies to the daughter cells. The <br/>genes which control cell division are among the most crucial in the <br/>genome. Damage to them often results in cancer. <br/> 11.1 Bacteria divide far more simply than do eukaryotes.<br/> 11.2 Chromosomes are highly ordered structures.<br/> 11.3 Mitosis is a key phase of the cell cycle.<br/> 11.4 The cell cycle is carefully controlled.<br/>12<br/>Sexual Reproduction and Meiosis <br/>Sexual reproduction is only possible because of a special form of cell <br/>division called meiosis that reduces the diploid number of chromosomes <br/>in half; fertilization then restores the diploid number. Sexual <br/>reproduction may have evolved as a way to repair damaged DNA, although <br/>other explanations are also being actively considered.<br/> 12.1 Meiosis produces haploid cells from diploid cells.<br/> 12.2 Meiosis has three unique features.<br/> 12.3 The sequence of events during meiosis involves two nuclear <br/>divisions.<br/> 12.4 The evolutionary origin of sex is a puzzle.<br/>13<br/>Patterns of Inheritance <br/>Mendel's theory of heredity rests squarely on the assumption that what <br/>is inherited is information rather than the traits themselves. Once <br/>researchers understood that the information resided on chromosomes, the <br/>reason for Mendelian segregation became clear.<br/> 13.1 Mendel solved the mystery of heredity.<br/> 13.2 Human genetics follows Mendelian principles.<br/> 13.3 Genes are on chromosomes.<br/>Genetics<br/>Part V Molecular Genetics<br/>14<br/>DNA: The Genetic Material <br/>The experiments demonstrating that DNA is the hereditary material are <br/>among the most elegant in biology. Its double helical structure leads <br/>directly to a mechanism for replicating the molecule that is simple and <br/>relatively free of errors.<br/> 14.1 What is the genetic material?<br/> 14.2 What is the structure of DNA?<br/> 14.3 How does DNA replicate?<br/> 14.4 What is a gene?<br/>15<br/>Genes and How They Work <br/>Gene expression is the mechanism translating the genetic information <br/>into the practical reality of what organisms are like. It involves first <br/>transcribing a working copy of a gene, then using that copy to direct <br/>the assembly of a specific protein.<br/> 15.1 The Central Dogma traces the flow of gene-encoded <br/>information.<br/> 15.2 Genes encode information in three-nucleotide code words.<br/> 15.3 Genes are first transcribed, then translated.<br/> 15.4 Eukaryotic gene transcripts are spliced.<br/>16<br/>Control of Gene Expression <br/>The key to controlling development is to control when particular genes <br/>are transcribed. This is done by proteins that can read the DNA double <br/>helix without unwinding it, slipping protein segments called "motifs" <br/>into the major groove of the double helix.<br/> 16.1 Gene expression is controlled by regulating transcription.<br/> 16.2 Regulatory proteins read DNA without unwinding it.<br/> 16.3 Bacteria limit transcription by blocking RNA polymerase.<br/> 16.4 Transcriptional control in eukaryotes operates at a <br/>distance. <br/>17<br/>Cellular Mechanisms of Development <br/>Vertebrate development is quite different from that of solid worms, <br/>insects, or plants, although it shares with these other approaches a <br/>common set of basic mechanisms. Detailed study of a few "model systems" <br/>has told us a great deal about how development occurs.<br/> 17.1 Development is a regulated process.<br/> 17.2 Multicellular organisms employ the same basic mechanisms of <br/>development.<br/> 17.3 Four model developmental systems have been extensively <br/>researched.<br/> 17.4 Aging can be considered a developmental process.<br/>18<br/>Altering the Genetic Message <br/>The genetic message can be altered by mutation, which changes or <br/>destroys its content, and by recombination, which alters gene location. <br/>Cancer results from mutation of growth-regulating genes, often as the <br/>result of cigarette smoking or diet.<br/> 18.1 Mutations are changes in the genetic message.<br/> 18.2 Cancer results from mutation of growth-regulating genes.<br/> 18.3 Recombination alters gene location.<br/> 18.4 Genomes are continually evolving.<br/>19<br/>Gene Technology <br/>Enzymes that cleave DNA at particular sites have allowed scientists to <br/>manipulate the genetic message, creating new combinations of genes that <br/>are revolutionizing medicine and agriculture. Every one of us will be <br/>affected by gene technology.<br/> 19.1 The ability to manipulate DNA has led to a new genetics.<br/> 19.2 Genetic engineering involves easily understood procedures.<br/> 19.3 Biotechnology is producing a scientific revolution.<br/>Evolution and Ecology <br/>Part VI Evolution<br/>20<br/>Genes within Populations <br/>Evolution occurs within populations when one allele becomes more <br/>frequent than another. The study of why allele frequencies change within <br/>populations has occupied geneticists for over a century, and a clear <br/>picture is now beginning to emerge.<br/> 20.1 Genes vary in natural populations.<br/> 20.2 Why do allele frequencies change in populations?<br/> 20.3 Selection can act on traits affected by many genes.<br/>21<br/>The Evidence for Evolution <br/>Adaptive allele changes within populations have been demonstrated many <br/>times, and a variety of evidence, much of it compelling, argues that <br/>these changes lead to the macroevolutionary changes familiar to us as <br/>the fossil record.<br/> 21.1 Fossil evidence indicates that evolution has occurred.<br/> 21.2 Natural selection can produce evolutionary change.<br/> 21.3 Evidence for evolution can be found in other fields of <br/>biology.<br/> 21.4 The theory of evolution has proven controversial.<br/>22<br/>The Origin of Species <br/>Species, the basic units of evolution, originate when two populations of <br/>a species adapt to different environments. Selection will tend to favor <br/>changes that inhibit gene flow between them, eventually creating a <br/>genetic barrier that isolates the populations.<br/> 22.1 Species are the basic units of evolution.<br/> 22.2 Species maintain their genetic distinctiveness through <br/>barriers to reproduction.<br/> 22.3 We have learned a great deal about how species form.<br/> 22.4 Clusters of species reflect rapid evolution.<br/>23<br/>How Humans Evolved <br/>Humans evolved in Africa from a bipedal kind of ape called an <br/>australopithecine some two million years ago. The first humans to leave <br/>Africa, H. erectus, spread across the earth over a million years ago. <br/>How modern humans replaced them is a matter of some controversy.<br/> 23.1 The evolutionary path to humans starts with the advent of <br/>primates.<br/> 23.2 The first hominids to evolve were australopithecines.<br/> 23.3 The genus Homo evolved in Africa.<br/> 23.4 Modern humans evolved quite recently.<br/> Part VII Ecology and Behavior<br/>24<br/>Population Ecology <br/>The way in which a population grows depends importantly upon how many <br/>young individuals it contains. The way in which a species reproduces <br/>represents an evolutionary trade-off between reproductive cost and <br/>investment in survival.<br/> 24.1 Populations are individuals of the same species that live <br/>together.<br/> 24.2 Population dynamics depend critically upon age distribution.<br/> 24.3 Life histories often reflect trade-offs between reproduction <br/>and survival.<br/> 24.4 Population growth is limited by the environment.<br/> 24.5 The human population has grown explosively in the last three <br/>centuries.<br/>25<br/>Community Ecology <br/>Organisms make complex evolutionary adjustments to living together <br/>within communities. Some adjustments involve cooperation, others <br/>capturing prey or avoiding being captured. <br/> 25.1 Interactions among competing species shape ecological <br/>niches.<br/> 25.2 Predators and their prey coevolve.<br/> 25.3 Evolution sometimes fosters cooperation.<br/> 25.4 Ecological succession may increase species richness.<br/>26<br/>Animal Behavior <br/>The study of animal behavior has historically been carried out in two <br/>quite different ways, which are only now merging into a unified view. <br/>One stressed fixed behaviors constrained by neural organization, the <br/>other flexible behaviors influenced by learning.<br/> 26.1 Ethology focuses on the natural history of behavior.<br/> 26.2 Comparative psychology focuses on how learning influences <br/>behavior.<br/> 26.3 Communication is a key element of many animal behaviors.<br/> 26.4 Migratory behavior presents many puzzles.<br/> 26.5 To what degree animals "think" is a subject of lively dispute.<br/>27<br/>Behavioral Ecology <br/>Much of the excitement in behavioral science today comes from analysis <br/>of how evolution has shaped, and is shaping, the behavior of animal <br/>species in natural populations. Often quite controversial, these studies <br/>combine theory and careful field observation.<br/> 27.1 Evolutionary forces shape behavior.<br/> 27.2 Reproductive behavior involves many choices influenced by natural <br/>selection.<br/> 27.3 There is considerable controversy about the evolution of <br/>social behavior.<br/> 27.4 Vertebrates exhibit a broad range of social behaviors.<br/>Evolution and Ecology <br/>Part VIII The Global Environment<br/>28<br/>Dynamics of Ecosystems <br/>Ecological systems are dynamic "machines" in which chemicals cycle <br/>between organisms and the environment and energy is used as it passes <br/>through the system. Much energy is lost to heat at each step of its <br/>journey through living things. In general, communities with more species <br/>interacting with one another are more stable.<br/> 28.1 Chemicals cycle within ecosystems.<br/> 28.2 Ecosystems are structured by who eats whom.<br/> 28.3 Energy flows through ecosystems.<br/> 28.4 Biodiversity promotes ecosystem stability.<br/>29<br/>The Biosphere <br/>The sun powers major movements of the atmosphere that circulate heat and <br/>moisture over the surface of the globe, creating different climates in <br/>different locales. Each characteristic climate favors a particular <br/>community of organisms adapted to living there.<br/> 29.1 Organisms must cope with a varied environment.<br/> 29.2 Climate shapes the character of ecosystems.<br/> 29.3 Biomes are widespread terrestrial ecosystems.<br/> 29.4 Aquatic ecosystems cover much of the earth.<br/>30<br/>The Future of the Biosphere <br/>The world's human population is growing at an explosive rate, placing a <br/>severe strain on the world's ecosystems. No one knows if the world can <br/>sustain the 6 billion people it now contains-and the population will <br/>soon grow much larger.<br/> 30.1 The world's human population is growing explosively.<br/> 30.2 Improvements in agriculture are needed to feed a hungry <br/>world.<br/> 30.3 Human activity is placing the environment under increasing <br/>stress.<br/> 30.4 Solving environmental problems requires individual <br/>involvement.<br/>31<br/>Conservation Biology <br/>The successive efforts to halt the world's alarming loss of biodiversity <br/>will depend critically on our gaining a better understanding of what <br/>forces threaten species survival, and how they can be counteracted.<br/> 31.1 The new science of conservation biology is focused on <br/>conserving biodiversity.<br/> 31.2 Vulnerable species are more likely to become extinct.<br/> 31.3 Causes of endangerment usually reflect human activities.<br/> 31.4 Successful recovery plans will need to be multidimensional.<br/> Simple Organisms<br/> Part IX Viruses and Simple Organisms<br/>32<br/>How We Classify Organisms <br/>The living world is a rich tapestry of diversity, teeming with different <br/>kinds of organisms. One of the great challenges of biology is to find <br/>sensible ways to name and classify kinds of organisms, ways that tell us <br/>about them and how they relate to each other.<br/> 32.1 Biologists name organisms in a systematic way.<br/> 32.2 Scientists construct phylogenies to understand the <br/>evolutionary relationships among organisms.<br/> 32.3 All living organisms are grouped into one of a few major <br/>categories.<br/>33<br/>Viruses <br/>Viruses are not considered organisms because they lack cellular <br/>structure. However, because they can replicate themselves within the <br/>cells of organisms, viruses are able to evolve, and are responsible for <br/>a broad array of serious diseases.<br/> 33.1 Viruses are strands of nucleic acid encased within a protein <br/>coat.<br/> 33.2 Bacterial viruses exhibit two sorts of reproductive cycles.<br/> 33.3 HIV is a complex animal virus.<br/> 33.4 Non-living infectious agents are responsible for many human <br/>diseases.<br/>34<br/>Bacteria <br/>Bacteria are the simplest organisms, composed of single cells that lack <br/>the complex internal organization seen in all other cells. Biologists <br/>believe bacteria were the first organisms to evolve on earth, and they <br/>are easily the most numerous and successful.<br/> 34.1 Bacteria are the smallest and most numerous organisms.<br/> 34.2 Bacterial cell structure is more complex than commonly <br/>supposed.<br/> 34.3 Bacteria exhibit considerable diversity in both structure <br/>and metabolism.<br/> 34.4 Bacteria are responsible for many diseases but also make <br/>important contributions to ecosystems.<br/>35<br/>Protists <br/>All eukaryotic organisms that are not fungi, plants, or animals are <br/>lumped together in a catch-all category called protists. Except for the <br/>marine algae, all protists are unicellular, but the diversity among <br/>protists is so great that it is difficult to compare them.<br/> 35.1 Eukaryotes probably arose by endosymbiosis.<br/> 35.1 The kingdom Protista is by far the most diverse of any <br/>kingdom.<br/> 35.2 Protists can be categorized into five groups.<br/>36<br/>Fungi <br/>Fungi are extraordinarily strange multicellular organisms whose cells <br/>share cytoplasm and nuclei. Fungi absorb their food from their <br/>surroundings, first excreting digestive enzymes, then soaking up the <br/>resulting soup of molecular fragments. <br/> 36.1 Fungi are unlike any other kind of organism.<br/> 36.2 Fungi are classified by their reproductive structures.<br/> 36.3 Fungi form two key mutualistic symbiotic associations.<br/>Plants<br/>Part X Plant Form and Function<br/>37<br/>Evolutionary History of Plants <br/>Plants are responsible for much of the photosynthesis that supports life <br/>on earth. Early plants resembled nonvascular mosses in having no <br/>internal structures to move water up and down the stem. Their vascular <br/>descendants added seeds and then flowers.<br/> 37.1 Plants have multicellular haploid and diploid stages in <br/>their life cycles.<br/> 37.2 Nonvascular plants are relatively unspecialized but <br/>successful in many terrestrial environments.<br/> 37.3 Seedless vascular plants have well-developed conducting <br/>tissues in their sporophytes.<br/> 37.4 Seeds protect and aid in the dispersal of plant embryos.<br/>38<br/>The Plant Body <br/>A plant is basically a tubular stem with roots attached to the bottom <br/>and leaves to the top. Growth occurs at the tip of the shoot, at the <br/>ends of the roots, and in a sheath around the plant stem. Roots gather <br/>in nutrients from the soil, while leaves carry out photosynthesis.<br/> 38.1 Meristems elaborate the plant body plan after germination.<br/> 38.2 Plants have three basic tissues, each composed of several <br/>cell types.<br/> 38.3 Root cells differentiate as they become distanced from the <br/>dividing root apical meristem.<br/> 38.4 Stems are the backbone of the shoot, transporting nutrients <br/>and supporting the aerial plant organs.<br/> 38.5 Leaves are adapted to support basic plant functions.<br/>39<br/>Nutrition and Transport in Plants <br/>Plants require a variety of mineral nutrients that they obtain from the <br/>soil. Nutrients are carried from the roots to the leaves dissolved in <br/>water, which is sucked up the stem through the xylem by transpiration <br/>from the leaves. Carbohydrates are carried from the leaves to the roots <br/>dissolved in water that travels down the phloem. <br/> 39.1 Plants require a variety of nutrients in addition to the <br/>direct products of photosynthesis.<br/> 39.2 Some plants have novel strategies for obtaining nutrients.<br/> 39.3 Water and minerals move upward through the xylem.<br/> 39.4 Dissolved sugars and hormones are transported in the phloem.<br/>Part XI Plant Growth and Reproduction<br/>40<br/>Early Plant Development <br/>The plant body develops in modules of leaf, shoot, and root. The course <br/>of the plant body's development is strongly influenced by the <br/>environment. Many plant structures, including seeds and fruits, have <br/>evolved to aid dispersal of offspring to new locations.<br/> 40.1 Plant embryo development establishes a basic body plan.<br/> 40.2 The seed protects the dormant embryo from water loss.<br/> 40.3 Fruit formation enhances the dispersal of seeds.<br/> 40.4 Germination initiates post-seed development.<br/>41<br/>How Plants Grow in Response to Their Environment <br/>Every plant cell contains a full set of hereditary information. <br/>Which genes are expressed is controlled by a set of plant hormones, including <br/>auxin, ethylene, and many others. These hormones interact with each <br/>other and with the environment to determine the pattern of growth.<br/> 41.1 Plant growth is often guided by environmental cues.<br/> 41.2 The hormones that guide growth are keyed to the environment.<br/> 41.3 The environment influences flowering.<br/> 41.4 Many short-term responses to the environment do not require <br/>growth.<br/>42<br/>Plant Reproduction <br/>Many plants can clone themselves by asexual reproduction. Some plants <br/>use the wind to transport pollen from male to female. A much more <br/>efficient delivery system is employed by flowering plants, which use <br/>insects to carry pollen from flower to flower.<br/> 42.1 Angiosperms have been incredibly successful, in part, <br/>because of their reproductive strategies.<br/> 42.2 Flowering plants use animals or wind to transfer pollen <br/>between flowers.<br/> 42.3 Many plants can clone themselves by asexual reproduction.<br/> 42.4 How long do plants and plant organs live?<br/>43<br/>Plant Genomics <br/>Plants organize their hereditary material in a more complex way than <br/>animals, with extensive regions of repetitive DNA and often many copies <br/>of chromosomes. Cloning plants in tissue culture and altering their <br/>genes have led to major agricultural advances.<br/> 43.1 Genomic organization is much more varied in plants than in <br/>animals.<br/> 43.2 Advances in plant tissue culture are revolutionizing <br/>agriculture.<br/> 43.3 Plant biotechnology now affects every aspect of agriculture.<br/>Animals<br/>Part XII Animal Diversity<br/>44<br/>The Noncoelomate Animals <br/>The simplest animals lack a coelomic body cavity. The most ancient are <br/>the sponges, which lack tissues. Many of these evolutionarily old <br/>noncoelomate animals are called "worms," but this simple designation <br/>hides a great diversity of form and function.<br/> 44.1 Animals are multicellular heterotrophs without cell walls.<br/> 44.2 The simplest animals are not bilaterally symmetrical.<br/> 44.3 Acoelomates are solid worms that lack a body cavity.<br/> 44.4 Pseudocoelomates have a simple body cavity.<br/> 44.5 The coming revolution in animal taxonomy will likely alter <br/>traditional phylogenies.<br/>45<br/>Mollusks and Annelids <br/>Mollusks and annelid worms, both of which originated in the sea and have <br/>similar larvae, are also very successful on land. Indeed, there are more <br/>terrestrial species of mollusks than there are terrestrial vertebrate <br/>species! <br/> 45.1 Mollusks were among the first coelomates.<br/> 45.2 Annelids were the first segmented animals.<br/> 45.3 Lophophorates appear to be a transitional group.<br/>46<br/>Arthropods <br/>Arthropods are easily the most successful animal group, particularly the <br/>insects. Along with the jointed appendages that are the hallmark of <br/>arthropods, insects evolved wings. There are more species of beetles <br/>than there are of any nonarthropod animal phylum.<br/> 46.1 The evolution of jointed appendages has made arthropods very <br/>successful.<br/> 46.2 The chelicerates all have fangs or pincers.<br/> 46.3 Crustaceans have branched appendages.<br/> 46.4 Insects are the most diverse of all animal groups.<br/>47<br/>Echinoderms <br/>The vertebrates closest relatives among the animals are echinoderms, <br/>what most people think of as "starfish." Like vertebrates, they have <br/>deuterostome development and an endoskeleton. Unlike vertebrates, <br/>however, echinoderms are radially symmetrical as adults.<br/> 47.1 The embryos of deuterostomes develop quite differently from <br/>those of protostomes.<br/> 47.2 Echinoderms are deuterostomes with an endoskeleton.<br/> 47.3 The six classes of echinoderms are all radially symmetrical <br/>as adults.<br/>48<br/>Vertebrates <br/>Vertebrates are members of the phylum Chordata, all of whose members <br/>have a notochord at some stage in their development. The hallmark of <br/>vertebrates is an interior skeleton of bone which provides a superb <br/>framework for muscle attachment.<br/> 48.1 Attaching muscles to an internal framework greatly improves <br/>movement.<br/> 48.2 Nonvertebrate chordates have a notochord but no backbone.<br/> 48.3 The vertebrates have an interior framework of bone.<br/> 48.4 The evolution of vertebrates involves invasions of sea, <br/>land, and air.<br/>Part XIII Animal Form and Function<br/>49<br/>Organization of the Animal Body <br/>Although they at first glance seem quite different from one another, all <br/>vertebrates are basically similar in body design, using the same array <br/>of tissues to form a similar array of organs. Vertebrates differ <br/>principally in the degree of terrestrial adaptation.<br/> 49.1 The bodies of vertebrates are organized into functional <br/>systems.<br/> 49.2 Epithelial tissue forms membranes and glands.<br/> 49.3 Connective tissues contain abundant extracellular material.<br/> 49.4 Muscle tissue provides for movement, and nerve tissue <br/>provides for control.<br/>50<br/>Locomotion <br/>Muscle tissue, because it can contract, allows animals to move about. <br/>Some animals, like fish and snakes, move their entire bodies, while <br/>others move limbs such as arms, legs, or wings. The contraction of <br/>muscle is powered by ATP and controlled by the nervous system.<br/> 50.1 A skeletal system supports movement in animals.<br/> 50.2 Skeletal muscles contract to produce movements at joints.<br/> 50.3 Muscle contraction powers animal locomotion.<br/>51<br/>Fueling Body Activities: Digestion <br/>Before the cells of an animal can assimilate fatty acids, sugars, and <br/>amino acids to use in manufacturing ATP, these "food" molecules must be <br/>cleaved out of far larger fats, carbohydrates, and proteins. This <br/>process of digestion takes place in the stomach and small intestine.<br/> 51.1 Animals employ a digestive system to prepare food for <br/>assimilation by cells.<br/> 51.2 Food is ingested, swallowed, and transported to the stomach.<br/> 51.3 The small and large intestines have very different <br/>functions.<br/> 51.4 Accessory organs, neural stimulation, and endocrine <br/>secretions assist in digestion.<br/> 51.5 All animals require food energy and essential nutrients.<br/>52<br/>Circulation <br/>The highway that carries materials from one place to another in the <br/>vertebrate body is a network of flexible pipes called arteries and <br/>veins. A muscular pump called the heart pushes a rich fluid called blood <br/>through these pipes to every organ in the body.<br/> 52.1 The circulatory systems of animals may be open or closed.<br/> 52.2 A network of vessels transports blood through the body.<br/> 52.3 The vertebrate heart has undergone progressive evolutionary <br/>change.<br/> 52.4 The cardiac cycle drives the cardiovascular system.<br/>53<br/>Respiration <br/>One of the most important cargos carried by blood are two gases, oxygen <br/>and carbon dioxide. In the lungs, blood picks up oxygen from the air and <br/>dumps carbon dioxide acquired from the body's tissues as a by-product of <br/>their respiratory metabolism. <br/> 53.1 Respiration involves the diffusion of gases.<br/> 53.2 Gills are used for respiration by aquatic vertebrates.<br/> 53.3 Lungs are used for respiration by terrestrial vertebrates.<br/> 53.4 Mammalian breathing is a dynamic process.<br/> 53.5 Blood transports oxygen and carbon dioxide.<br/>Animals<br/>Part XIV Regulating the Animal Body<br/>54<br/>The Nervous System <br/>The activities of the many organs of the vertebrate body are coordinated <br/>by the nervous system, an extensive network of neuron cells connecting <br/>all organs of the body. At a central coordinating center, the brain, <br/>information is processed, associations made, and commands given.<br/> 54.1 The nervous system consists of neurons and supporting cells.<br/> 54.2 Nerve impulses are produced on the axon membrane.<br/> 54.3 Neurons form junctions called synapses with other cells.<br/> 54.4 The central nervous system consists of the brain and spinal <br/>cord.<br/> 54.5 The peripheral nervous system consists of sensory and motor <br/>neurons.<br/>55<br/>Sensory Systems <br/>Information used by the nervous system to coordinate the body's <br/>activities comes from a system of sensors that collects information <br/>about the body's condition, its position in space, and what is going on <br/>around it. Vertebrates differ substantially in which sensors they <br/>employ.<br/> 55.1 Animals employ a wide variety of sensory receptors.<br/> 55.2 Mechanical and chemical receptors sense the body's <br/>condition.<br/> 55.3 Auditory receptors detect pressure waves in the air.<br/> 55.4 Optic receptors detect light over a broad range of <br/>wavelengths.<br/> 55.5 Some vertebrates use heat, electricity, or magnetism for <br/>orientation.<br/>56<br/>The Endocrine System <br/>The vertebrate nervous system uses long-lasting chemical signals called <br/>hormones to coordinate many physiological and developmental processes. <br/>The cells that secrete these hormones are often regulated by a set of <br/>command hormones released by the brain.<br/> 56.1 Regulation is often accomplished by chemical messengers.<br/> 56.2 Lipophilic and polar hormones regulate their target cells <br/>by different means.<br/> 56.3 The hypothalamus controls the secretions of the pituitary <br/>gland.<br/> 56.4 Endocrine glands secrete hormones that regulate many body <br/>functions.<br/>57<br/>The Immune System <br/>Vertebrates defend themselves from infection by viruses, bacteria, and <br/>other microbes with an army of circulating cells that seek out and check <br/>the identity of all cells in the body. When a stranger is identified, <br/>other "killer" cells are called in to deal with the invader.<br/> 57.1 Many of the body's most effective defenses are nonspecific.<br/> 57.2 Specific immune defenses require the recognition of <br/>antigens.<br/> 57.3 T cells organize attacks against invading microbes.<br/> 57.4 B cells label specific cells for destruction.<br/> 57.5 All animals exhibit nonspecific immune response but specific <br/>ones evolved invertebrates.<br/> 57.6 The immune system can be defeated.<br/>58<br/>Maintaining the Internal Environment <br/>Vertebrates maintain internal conditions at constant values, often quite <br/>different from those of their environment. This is particularly true of <br/>temperature and salt levels. Vertebrates go to great pains to maintain <br/>body temperature and avoid water loss or gain.<br/> 58.1 The regulatory systems of the body maintain homeostasis.<br/> 58.2 The extracellular fluid concentration is constant in most <br/>vertebrates.<br/> 58.3 The functions of the vertebrate kidney are performed by <br/>nephrons.<br/> 58.4 The kidney is regulated by hormones.<br/>59<br/>Sex and Reproduction 1<br/>Vertebrates usually reproduce sexually, although asexual reproduction is <br/>not impossible for them. In the sea, females release eggs into the water <br/>for external fertilization by the males' sperm. On land, evolution has <br/>favored internal fertilization.<br/> 59.1 Animals employ both sexual and asexual reproductive <br/>strategies.<br/> 59.2 The evolution of reproduction among the vertebrates has led <br/>to internalization of fertilization and development.<br/> 59.3 Male and female reproductive systems are specialized for <br/>different functions.<br/> 59.4 The physiology of human sexual intercourse is becoming <br/>better known.<br/>60<br/>Vertebrate Development <br/>In vertebrates, the path of development from fertilization to birth is <br/>well known. The development of the embryo undergoes its key stages early <br/>on, determining the basic architecture of the body and its tissues. <br/>Thereafter, much of what occurs is growth.<br/> 60.1 Fertilization is the initial event in development.<br/> 60.2 Cell cleavage and the formation of a blastula set the stage <br/>for later development.<br/> 60.3 Gastrulation forms the three germ layers of the embryo.<br/> 60.4 Body architecture is determined during the next stages of <br/>embryonic development.<br/> 60.5 Human development is divided into trimesters. |