Table of Contents

Special-Interest Essays     xliii
The Organization of the Body
Humans in the World of Biology     1
All Living Things Share Basic Characteristics     2
Living Organisms are Classified by Evolutionary Relationships     4
Life has many Levels of Organization     5
The Scientific Method Gathers Information for Drawing Logical Conclusions     6
Inductive and deductive reasoning help solve problems     9
Clinical trials follow strict guidelines     10
Epidemiological studies look for patterns in populations     10
Critical Thinking Helps Us Make Informed Decisions     11
Environmental Issue: Medicinal Plants and the Shrinking Rain Forest     7
Social Issue: Scientific Misconduct     11
Chemistry Comes to Life     14
Basic Chemistry Helps Us Understand Human Biology     15
Atoms contain protons, neutrons, and electrons     15
Elements combine to form compounds     17
The atoms or ions of a compound are held together by chemical bonds     17
Water is essential to life     20
Carbohydrates, Lipids, Proteins, and Nucleic Acids Are the Major Molecules of Life     23
Carbohydrates supply energy to cells     25
Lipids store energy and form cellmembranes     26
Proteins provide structure and speed up chemical reactions     28
The nucleic acids are DNA and RNA     31
ATP is a nucleotide that releases energy     32
Social Issue: The Ethics of Radiation Research on Humans     18
Environmental Issue: What Is Happening to the Rain?     24
The Cell     37
Our Cells Are Highly Structured     38
Eukaryotic cells are structurally more complex than prokaryotic cells     38
Cells are very small     39
The plasma membrane has diverse functions     39
Organelles are specialized compartments within cells     45
The cytoskeleton provides support and movement     50
Our Cells Use Cellular Respiration and Fermentation to Generate ATP     53
Cellular respiration requires oxygen     54
Fermentation does not require oxygen     59
Environmental Issue: Asbestos: The Deadly Miracle Material     50
Body Organization and Homeotasis     62
The Organization of the Human Body Increases in Complexity from Cells to Organ Systems     63
Groups of similar cells form tissues     63
Many tissues have specialized junctions between the cells     68
Tissues combine to form organs that in turn form organ systems     68
Most organs are housed in body cavities that are lined with membranes     68
The Skin Is an Organ System     71
Skin protects, regulates body temperature, and excretes     71
The skin has two layers     71
Skin color is determined by pigment and blood flow     73
Hair, nails, and glands are skin derivatives     74
Homeostasis Is a State of Relative Internal Constancy     76
Homeostasis is maintained by negative feedback mechanisms     76
The hypothalamus regulates body temperature     76
Health Issue: Fun in the Sun? Sunlight and Skin Cancer     75
Health Issue: Acne: The Misery, the Myths, and the Medications     79
Control and Coordination of the Body
The Skeletal System     82
Bones Function in Support, Movement, Protection, Storage, and Blood Cell Production     83
Bones Have a Hard Outer Layer of Compact Bone Surrounding Spongy Bone     83
Bone Is Living Tissue     84
Most of the skeleton begins as a cartilage model     84
Hormones regulate bone growth     85
Bone Fractures Are Healed by Fibroblasts and Osteoblasts     85
Bones are Continuously Remodeled     86
We Divide the Human Skeleton into Two Parts      86
The axial skeleton protects our internal organs     86
The appendicular skeleton makes locomotion possible     90
Joints Are Junctures between Bones     92
Synovial joints permit flexibility     92
Health Issue: Osteoporosis: Fragility and Aging     89
The Muscular System     97
The Muscular System Moves Our Body Parts and Maintains Our Posture     98
Most Skeletal Muscles Work in Pairs     98
Sarcomeres Are the Contractile Units of Muscles     100
Skeletal muscle contracts when actin filaments slide across myosin filaments     100
Calcium ions and regulatory proteins control contraction     102
Nerves stimulate muscle contraction     102
Muscular dystrophy causes progressive muscle deterioration     102
The Strength of Muscle Contraction Depends on the Number of Motor Units Stimulated     102
The Strength of Contraction Increases If a Muscle Is Stimulated before It Has Relaxed     104
ATP for Muscle Contraction Comes from Many Sources     104
Slow-Twitch and Fast-Twitch Muscle Cells Differ in Contraction Speed and Duration     105
Aerobic Exercise Increases Endurance; Resistance Exercise Builds Muscle     106
Social Issue: Building Muscle Fair and Square? Anabolic Steroid Abuse      107
Neurons: The Matter of the Mind     110
Neurons and Neuroglial Cells Are the Cells of the Nervous System     111
Neuroglial cells support, protect, insulate, and nurture neurons     111
Neurons can be sensory, motor, or associative     111
Neurons Have Dendrites, a Cell Body, and an Axon     112
Axons and dendrites are bundled together to form nerves     112
The myelin sheath increases the rate of conduction and helps in repair     113
The Nerve Impulse Is an Electrochemical Signal     114
Ions move passively through ion channels     114
The sodium-potassium pump uses ATP to transport sodium ions out and potassium ions in     114
The inside of a resting neuron has a negative charge relative to the outside     114
An action potential is a reversal and restoration of the charge difference across the membrane     114
The sodium-potassium pump restores the original distribution of ions     115
Action potentials are all-or-nothing events     115
A neuron cannot fire during the refractory period     117
Synaptic Transmission Is Communication between Neurons     117
Synaptic transmission involves the release of neurotransmitter and the opening of ion channels     117
Neurons "sum up" input from excitatory and inhibitory synapses     118
The neurotransmitter is quickly removed from the synapse     118
Different neurotransmitters play different roles     119
Environmental Issue: Environmental Toxins and the Nervous System     120
The Nervous System     124
The Nervous System Consists of the Central and Peripheral Nervous Systems     125
Bone, Membranes, and Cerebrospinal Fluid Protect the Central Nervous System     126
The Brain Is the Central Command Center     127
The cerebrum is the conscious part of the brain     128
The thalamus allows messages to pass to the cerebral cortex     130
The hypothalamus is essential to homeostasis     130
The cerebellum is an area of sensory-motor coordination     131
The brain stem controls many of life's basic processes and connects the brain and spinal cord     131
The limbic system is involved in emotions and memory     132
The reticular activating system filters sensory input     132
The Spinal Cord Transmits Messages to and from the Brain and Is a Reflex Center     133
The Peripheral Nervous System Consists of the Somatic and Autonomic Nervous Systems     134
The somatic nervous system controls conscious functions     134
The autonomic nervous system controls internal organs     134
Disorders of the Nervous System Vary in Health Significance     135
Headaches have several possible causes     135
Strokes occur when the brain is deprived of blood     138
Coma is a lack of response to all sensory input     138
Spinal cord injury results in impaired function below the site of injury     138
Health Issue: Meningitis: Bacterial-Type and West Nile Virus     126
Health Issue: To Sleep, Perchance to Dream     137
Special Topic: Drugs and the Mind     142
Psychoactive Drugs Alter Communication between Neurons     143
Drug Dependence Causes Continued Drug Use     143
Alcohol Depresses the Central Nervous System     144
The rate of alcohol absorption depends on its concentration     144
Alcohol is distributed to all body tissues     144
The rate of elimination of alcohol from the body cannot be increased     145
Alcohol has many health-related effects     146
Marijuana's Psychoactive Ingredient Is THC     147
Marijuana binds to THC receptors in the brain     148
Long-term marijuana use has many effects on the body     148
Legalization of medical marijuana is controversial     148
Stimulants Excite the Central Nervous System     149
Cocaine augments the neurotransmitters dopamine and norepinephrine     149
Amphetamines augment the neurotransmitters dopamine and norepinephrine     150
Hallucinogenic Drugs Alter Sensory Perception     150
Sedatives Depress the Central Nervous System     151
Opiates Reduce Pain     151
Sensory Systems     152
Sensory Receptors Generate Electrochemical Messages in Response to Stimuli     153
Receptors Are Classified by the Type of Stimulus to Which They Respond     153
Receptors for the General Senses Are Distributed throughout the Body     154
Mechanoreceptors detect touch and pressure     154
Cold and heat receptors detect temperature change     154
Muscle spindles and Golgi tendon organs detect body and limb position     154
Pain is caused by any sufficiently strong stimulus     155
Vision Depends on the Eye     156
The wall of the eyeball has three layers     156
The eye has two fluid-filled chambers     156
Sharp vision requires the image to be focused on the retina     157
Light changes the shape of pigment molecules, which generate neural messages     159
Vision in dim light depends on rods     160
Color vision depends on cones     161
Hearing Depends on the Ear     162
The ear collects and amplifies sound waves and converts them to neural messages     163
Variations in the movements of the basilar membrane determine loudness and pitch     165
Hearing loss can be conductive or sensorineural     165
Ear infections can occur in the ear canal or in the middle ear     168
Balance Depends on the Vestibular Apparatus of the Inner Ear     168
Smell and Taste Are the Chemical Senses     170
Health Issue: Correcting Vision Problems     160
Environmental Issue: Noise Pollution     167
The Endocrine System     174
The Endocrine System Communicates Using Chemical Messages     175
Hormones are the messengers of the endocrine system     175
Feedback mechanisms regulate the secretion of hormones     176
Hormones Influence Growth, Development, Metabolism, and Behavior     178
Pituitary hormones often prompt other glands to release hormones     178
Thyroid hormones regulate metabolism and decrease blood calcium     182
Parathyroid hormones increase blood calcium     185
The adrenal glands secrete stress hormones     185
Hormones of the pancreas regulate blood glucose      188
Hormones of the thymus gland promote maturation of white blood cells     192
The pineal gland secretes melatonin     192
Other Chemical Messengers Act Locally     193
Health Issue: Is It Hot in Here, or Is It Me? Hormone Replacement Therapy and Menopause     188
Health Issue: Hormones and Our Response to Stress     191
Health Issue: Melatonin: Miracle Supplement or Potent Drug Misused by Millions?     193
Maintenance of the Body
Blood     197
Blood Functions in Transportation, Protection, and Regulation     198
Blood Consists of Plasma and Formed Elements     198
Plasma is the liquid portion of blood     198
Stem cells give rise to the formed elements     199
Platelets are cell fragments essential to blood clotting     199
White blood cells help defend the body against disease     199
Red blood cells transport oxygen     201
The effects of blood cell disorders depend on the type of blood cell affected     203
Blood Types Are Determined by Antigens on the Surface of Red Blood Cells     205
Blood Clotting Occurs in a Regulated Sequence of Events     208
Environmental Issue: Lead Poisoning     204
The Circulatory System     211
The Cardiovascular System Consists of the Blood Vessels and the Heart     212
The Blood Vessels Conduct Blood in Continuous Loops     212
Arteries carry blood away from the heart     212
Capillaries are sites of exchange with body cells     215
Veins return blood to the heart     216
The Heart Is a Muscular Pump     218
Blood flows through the heart in two circuits     218
Coronary circulation serves the heart muscle     220
The cardiac cycle is the sequence of heart muscle contraction and relaxation     220
The rhythmic contraction of the heart is due to its internal conduction system     221
An electrocardiogram is a recording of the electrical activities of the heart     222
Blood pressure is the force blood exerts against blood vessel walls     223
Cardiovascular Disease Is a Major Killer in the United States     225
High blood pressure can kill without producing symptoms     225
Atherosclerosis is a buildup of lipids in the artery walls     225
Coronary artery disease is atherosclerosis in the coronary arteries     227
Heart attack is the death of heart muscle     228
The Lymphatic System Functions in the Circulatory and Immune Systems     229
Health Issue: The Cardiovascular Benefits of Exercise     226
Body Defense Mechanisms     234
The Body's Defense System Targets Pathogens and Cancerous Cells     235
The Body Has Three Lines of Defense     235
The first line of defense consists of physical and chemical barriers that prevent entry of pathogens     235
The second line of defense includes defensive cells and proteins, inflammation, and fever     236
The third line of defense, the immune response, has specific targets and memory     240
The Immune System Distinguishes Self from Nonself     240
The Immune System Mounts Antibody-Mediated Responses and Cell-Mediated Responses     241
The Cell-Mediated Immune Response and the Antibody-Mediated Immune Response Have the Same Steps     242
B cells mount an antibody-mediated immune response against antigens free in the blood or bound to a cell surface     245
Cytotoxic T cells mount a cell-mediated defense against antigen-bearing cells     246
Immunological memory permits a more rapid response on subsequent exposure to the antigen     247
Suppressor T cells turn off the immune response     248
Immunity Can Be Active or Passive     248
Monoclonal Antibodies Are Used in Research, Clinical Diagnosis, and Disease Treatment     248
The Immune System Can Cause Problems     249
Autoimmune disorders occur when the immune system attacks the body's own cells     249
Allergies are immune responses to harmless substances     250
Health Issue: The Fear That Vaccines Cause Autism     249
Health Issue: Rejection of Organ Transplants     250
Special Topic: Infectious Disease     256
Pathogens Are Disease-Causing Organisms     257
Certain bacteria produce toxins that cause disease     257
Viruses can damage the host cell when they leave the cell after replication or when they are incorporated into the cell's chromosomes     259
Protozoans cause disease by producing toxins and enzymes     261
Fungi often cause disease by secreting enzymes that digest cells     262
Parasitic worms cause disease by releasing toxins, feeding off blood, or competing with the host for food     262
Prions induce disease by causing normal proteins to become misfolded and clump together     262
Disease Is Spread When a Pathogen Enters the Body through Contact, Consumption, or a Vector     263
Infectious Diseases Remain a Cause for Concern     265
New diseases are emerging, and some old diseases are reappearing     265
Epidemiologists track diseases     267
The Respiratory System     268
In the Respiratory System, Oxygen and Carbon Dioxide Are Exchanged across a Moist Body Surface      269
The nose filters and conditions incoming air and has receptors for the sense of smell     270
The sinuses lighten the head and condition inhaled air     271
The pharynx is a passageway for food and air     272
The larynx is an adjustable entryway that produces the voice     272
The trachea is the windpipe     273
The bronchial tree is a system of air tubules that conducts air     273
The alveoli of the lungs are surfaces for gas exchange     274
Pressure Changes within the Lungs Cause Breathing     275
Inhalation occurs when the pressure in the lungs decreases     275
Exhalation occurs when the pressure in the lungs increases     275
The volume of air moved into and out of the lungs is an indication of health     276
Blood Transports Gases between the Lungs and the Cells     277
Most oxygen is carried by hemoglobin     277
Most carbon dioxide is transported as bicarbonate ions     277
Breathing Is Controlled Primarily by Respiratory Centers in the Brain     278
Brain centers control the basic breathing pattern     278
Depth and rate of breathing are affected by chemoreceptors     278
Respiratory Disorders Have Many Causes     280
The common cold is caused by many types of viruses     280
The flu is caused by three types of viruses     280
Pneumonia is an inflammation of the lungs     280
Strep throat can have serious consequences     280
Tuberculosis causes tubercles to form in the lungs     283
Bronchitis is an inflammation of the bronchi     283
Emphysema is caused by the destruction of alveoli     283
Social Issue: Bird Flu, Will It Become a Pandemic?     281
Health Issue: Surviving a Common Cold     282
Environmental Issue: Air Pollution and Human Health     284
Special Topic: Smoking and Disease     287
Smoking Is the Leading Cause of Death in the United States     288
Cigarette Smoke Contains Poisons and Cancer-Causing Substances     288
Smoking Causes Several Deadly Diseases     289
Smoking causes lung disease     289
Smoking causes cancer     290
Smoking causes heart disease     292
Smoking causes other health problems     292
Smoking Poses Additional Health Risks for Women     292
Passive Smoking Causes Serious Health Problems     293
No Cigarette Is Safe     294
The Health Benefits of Quitting Smoking Are Numerous     294
The Digestive System      296
The Digestive System Consists of a Long Tube That Runs through the Body, Along with Accessory Glands     297
The Digestive System is Divided into Specialized Compartments for Food Processing     297
The mouth begins mechanical digestion and the chemical digestion of starch     297
The pharynx is shared by the digestive and respiratory systems     300
The esophagus conducts food from the pharynx to the stomach     300
The stomach stores and liquefies food and begins protein digestion     300
The small intestine is the primary site of digestion and absorption     302
The pancreas, liver, and gallbladder are accessory organs that aid the processes of digestion and absorption within the small intestine     304
The large intestine absorbs water and other useful substances     308
Nerves and Hormones Control Digestive Activities     310
Health Issue: Heartburn and Peptic Ulcers-Those Burning Sensations     307
Special Topic: Nutrition and Weight Control     313
MyPyramid Is a Food Guide for Planning a Healthy Diet     314
Nutrients Provide Energy or Have a Structural or Functional Role in the Body     314
Lipids include fats, oils, and cholesterol     314
Carbohydrates include sugars, starches, and dietary fiber     317
Proteins are chains of amino acids     319
Vitamins are needed in small amounts to promote and regulate the body's chemical reactions     320
Minerals play structural and functional roles in the body     322
Water is critical and needed in large amounts     323
Food Labels Help Us Make Wise Food Choices     323
For Body Energy Balance, Calories Gained in Food Must Equal Calories Used     323
Obesity is Body Weight 20% or More above the Body Weight Standard     325
Successful Weight-Loss Programs Usually Involve Reducing Calorie Intake, Increasing Calorie Use, and Changing Behavior     325
Anorexia Nervosa and Bulimia Are Eating Disorders That Create Calorie Deficits     327
The Urinary System     329
Organs from Several Body Systems Eliminate Waste     330
By Producing Urine, the Kidneys Maintain Homeostasis     331
Each kidney has three regions     331
Nephrons are the functional units of the kidneys     331
The kidneys help maintain acid-base balance     336
The kidneys help conserve water     336
Hormones influence kidney function     337
The kidneys help produce red blood cells and activate vitamin D     338
Dialysis and Transplant Surgery Help When Kidneys Fail     339
Dialysis cleanses the blood     339
Renal function can be restored with a kidney transplant     342
Urination Has Involuntary and Voluntary Components     343
Bacteria Can Enter the Urethra and Cause Urinary Tract Infections     345
Health Issue: Kidney Stones and Their Shocking Treatment     340
Health Issue: Urinalysis: What Your Urine Says about You     344
Reproduction
Reproductive Systems     349
The Gonads Produce Gametes and Sex Hormones     350
A Male's Reproductive Role Differs from a Female's     350
The Male Reproductive System Delivers Sperm to the Egg     350
The testes produce sperm and male hormones     351
The duct system stores and transports sperm     352
The accessory glands produce most of the volume of semen     352
The penis transfers sperm to the female     353
As sperm develop, changes occur in the number of chromosomes and the structure and function of cells     353
The interplay of hormones controls male reproductive processes     354
The Female Reproductive System Produces the Eggs and Nurtures the Embryo and Fetus     355
The ovaries produce eggs and female hormones     355
The oviducts transport the immature egg, zygote, and early embryo     355
The uterus supports the growth of the developing embryo     355
External genitalia lie outside the vagina     357
The breasts produce milk to nourish the baby     357
The events of the ovarian cycle lead to release of an egg     357
The interplay of hormones coordinates the ovarian and menstrual cycles     358
Menopause ends a woman's reproductive cycles     362
Problems with the Female Reproductive System Vary in the Severity of Health Consequences     362
The Human Sexual Response Has Four Stages     364
Birth Control Is the Prevention of Pregnancy     364
Abstinence is refraining from intercourse     364
Sterilization may involve cutting and sealing gamete transport tubes     364
Hormonal contraception interferes with regulation of reproductive processes     365
Intrauterine devices prevent the union of sperm and egg and implantation     366
Barrier methods of contraception prevent the union of sperm and egg     366
Spermicidal preparations kill sperm     366
Fertility awareness is the avoidance of intercourse when fertilization could occur     367
The morning-after pill is emergency contraception     367
Health Issue: Breast Cancer     358
Environmental Issue: Environmental Estrogens      363
Special Topic: Sexually Transmitted Diseases and AIDS     370
STDs Are Extremely Common and Can Have Long-Lasting Effects     371
STDs Caused by Bacteria Can Be Cured with Antibiotics     371
Chlamydia can cause pain during urination, PID, or no symptoms     371
Gonorrhea can cause pain during urination, PIG, or no symptoms     372
Syphilis can progress though three stages when untreated     373
STDs Caused by Viruses Can Be Treated but Not Cured     373
Genital herpes can cause painful, fluid-filled blisters     374
Genital warts can lead to cervical, penile, or anal cancer     375
An HIV Infection Progresses to AIDS     376
HIV/AIDS is a global epidemic     377
HIV consists of RNA and enzymes encased in a protein coat     377
HIV enters the cells, rewrites its RNA as DNA, inserts DNA into the host chromosome, and replicates     377
Most HIV is transmitted through sexual contact, intravenous drug use, or from a pregnant woman to her fetus     377
Sites of HIV infection include the immune system and the brain     379
An HIV infection progresses through several stages as helper T cell numbers decline     379
Treatments for HIV infection are designed to block specific steps in HIV's replication cycle      381
Development throughout Life     382
Human Life Has Two Main Periods of Development     383
The Prenatal Period Begins at Fertilization and Ends at Birth     383
Fertilization, cleavage, and implantation characterize the pre-embryonic period     383
Tissues and organs form during the embryonic period     388
Rapid growth charactetizes the fetal period     393
Birth Is the Transition from Prenatal to Postnatal Development     396
True labor has three stages     396
The placenta may send the signal to initiate labor     397
Drugs and breathing techniques can relieve pain during childbirth     397
Environmental Disruptions during the Embryonic Period Cause Major Birth Defects     398
The Mother's Mammary Glands Produce Milk     398
The Postnatal Period Begins with Birth and Continues into Old Age     399
Possible causes of aging     400
Medical advances and a healthy lifestyle can help achieve a high-quality old age     401
Health Issue: Making Babies, but Not the Old-Fashioned Way     389
Genetics and Development
Chromosomes and Cell Division     405
The Human Life Cycle Has Two Types of Cell Division     406
Chromosomes Consist of DNA and Protein     406
Our Cells Divide in a Characteristic Cyclic Pattern     407
Interphase is a period of growth and preparation for cell division     407
Division of body cells entails division of the nucleus and the cytoplasm     408
Mitosis has four stages     408
Cytokinesis occurs toward the end of mitosis     412
Meiosis Forms Haploid Gametes     412
Meiosis keeps the chromosome number constant over generations and increases genetic variability in the population     412
Meiosis involves two cell divisions     412
Crossing over and independent assortment cause genetic recombination during meiosis     417
Failure of chromosomes to separate during meiosis creates cells with extra or missing chromosomes     417
Health Issue: Turner Syndrome and Klinefelter Syndrome     420
Special Topic: Stem Cells-The Body's Repair Kit     424
Stem Cells Are Unspecialized Cells That Divide Continually and Can Be Made to Develop into Different Tissue Types     425
There Are Several Sources of Human Stem Cells     425
Embryonic stem cells can be harvested from unused embryos created for in vitro fertilization     425
Adult stem cells exist in many tissues     425
Stem cells can be harvested from umbilical cord blood     426
Embryonic stem cells can be created by somatic cell nuclear transfer     427
Embryonic Stem Cell Research Raises Ethical and Political Controversy     429
Genetics and Human Inheritance     430
Principles of Inheritance Help Us Predict How Simple Traits Are Passed to the Next Generation     431
During gamete formation, alleles segregate and assort independently     432
Mendelian genetics considers patterns of inheritance     432
Pedigrees help us to ascertain genotype     435
A dominant allele often produces a protein that the recessive allele does not     437
Codominant alleles both produce functioning gene products     437
In incomplete dominance, the heterozygote has an intermediate phenotype     437
In pleiotropy, one gene has many effects     438
Certain genes have multiple alleles in a population     438
Most traits are controlled by many genes     438
Genes on the same chromosome are usually inherited together     440
Sex-linked genes are located on the sex chromosomes     440
Sex-influenced genes are autosomal genes whose expression is influenced by sex hormones     441
Breaks in Chromosomes Change Chromosomal Structure and Function     441
Certain Genetic Disorders Can Be Detected by Laboratory Tests     441
Social Issue: Gene Testing      443
DNA and Biotechnology     447
DNA Is a Double Helix Consisting of Two Strings of Nucleotides     448
During Replication of DNA, Each Original Strand Serves as a Template for a New Strand     448
DNA Codes for RNA, Which Codes for Protein     449
Transcription is RNA synthesis     450
Translation is protein synthesis     451
Mutations Result from Nucleotide Substitution, Insertion, or Deletion     453
Gene Activity Can Be Turned On or Off     455
Coiling and uncoiling of chromosomes regulate gene activity at the chromosome level     455
Certain genes regulate the activity of other genes     455
Chemical signals regulate gene activity     455
Genetic Engineering Is the Manipulation of DNA for Human Purposes     456
Recombinant DNA is made of DNA from different sources     456
Genetic engineering produces proteins of interest or transgenic organisms with desirable traits     458
Gene therapy replaces faulty genes with functional genes     460
Genomics Can Be Used to Study How Genes Function and How Diseases Are Inherited     463
The Human Genome Project sequenced a representative human genome     463
Microarray analysis is a useful tool in genomics     464
Comparing genomes of different species can be useful     464
Health Issue: Genetically Modified Food     461
Social Issue: Forensic Science, DNA, and Personal Privacy     465
Special Topic: Cancer     468
Cancer Is Uncontrolled Cell Division     469
Tumors can be benign or malignant     469
Tumor development progresses through stages     469
Cancer Begins with a Single Cell That Escapes Normal Control Mechanisms     470
Cancer cells lose restraints on cell division     471
Cancer cells do not self-destruct when their DNA is damaged     472
Cancer cells divide indefinitely     473
Cancer cells attract a blood supply     473
Cancer cells do not adhere to neighboring cells     474
Body defense cells destroy cancer cells     474
Viruses, Certain Chemicals, and Radiation Can Cause Cancer     475
Certain viruses can disrupt genetic control of cell division     475
Some chemicals can cause mutations     475
Radiation can cause mutations     475
Certain Lifestyle Habits Reduce the Risk of Cancer     475
There Are Several Ways to Diagnose Cancer     477
Surgery, Radiation, and Chemotherapy Are Conventional Ways to Treat Cancer     478
Surgery is used to remove tumors     478
Radiation therapy is used to kill localized cancer cells     478
Chemotherapy is used to kill cancer cells throughout the body     478
Immunotherapy boosts immune responses against cancer cells     478
Inhibition of blood vessel formation may slow the spread of cancer cells     479
Gene therapy may someday help fight cancer in several ways     479
Evolution and Ecology
Evolution and Our Heritage     480
Life Evolved on the Earth about 3.8 Billion Years Ago     481
Inorganic molecules formed small organic molecules     481
Small organic molecules joined to form larger molecules     481
Macromolecules aggregated into droplets     482
The Scale of Evolutionary Change May Be Small or Large     483
Microevolution is small-scale evolutionary change over short periods of time     483
Macroevolution is large-scale evolutionary change over long periods of time     485
Evidence of Evolution Comes from Diverse Sources     486
The fossil record provides evidence of evolution     486
Geographic distributions reflect evolutionary history     488
Comparative anatomy and embryology reveal common descent     488
Comparative molecular biology also reveals evolutionary relationships      489
Human Roots Trace Back to the First Primates     489
Primates have distinct characteristics     490
Discussions of human origins often evoke controversy     493
Misconceptions distort the picture of human evolution     493
Walking on two feet was a critical step in hominid evolution     494
Social issue: Conducting Research on Our Relatives     492
Ecology, the Environment, and Us     501
The Earth Is a Closed Ecosystem with Energy as the Only Input     502
The Biosphere Is the Part of the Earth Where Life Exists     502
Ecological Succession Is the Change in Species Occupying a Given Location over Time     502
Energy Flows through Ecosystems from Producers to Consumers     503
Food chains and food webs depict feeding relationships     503
Energy is lost as it is transferred through trophic levels     505
Ecological pyramids depict energy or biomass at each trophic level     505
Ecological pyramids have health and environmental ramifications     505
Chemicals Cycle through Ecosystems     509
Water cycles between the atmosphere and land     509
Carbon cycles between the environment and living bodies     509
Nitrogen cycles through several nitrogenous compounds      511
Phosphorus cycles between rocks and living organisms     512
Humans Can Upset Biogeochemical Cycles     512
Humans sometimes cause shortage or pollution of water     513
Atmospheric levels of carbon dioxide affect global temperatures     514
Disruptions to the nitrogen and phosphorus cycles can cause eutrophication     515
Environmental Issue: Global Warming     516
Human Populations, Limited Resources, and Pollution     519
Populations Change in Size over Time     520
Rates of addition and subtraction determine population growth rate     520
The age structure of a population influences future growth     520
Immigration and emigration affect population size     521
The Human Population Is Increasing, but Its Rate of Growth Is Slowing     521
Environmental Factors Regulate Population Size     522
The Growing Human Population Has Altered the Earth's Carrying Capacity     523
The human population may be reaching the earth's carrying capacity     523
Human activities cause pollution     524
Human activities deplete the earth's resources     525
Human activities are reducing biodiversity     525
Our Future Depends on the Decisions We Make Today     527
Social Issue: Maintaining Our Remaining Biodiversity     526
Glossary     G-1
Illustration Credits     C-1
Metric-English System Conversions     A-1
Selected Answers to Reviewing the Concepts Questions     A-3
Hints for Applying the Concepts Questions     A-5
Index     I-1