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» Resource Table of Contents

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1	Studying Life

Why are frogs croaking?

1.1	What Is Biology?

1.1.1	Living organisms consist of cells
1.1.2	The diversity of life is due to evolution by natural selection
1.1.3	Biological information is contained in a genetic language common to all organisms
1.1.4	Cells use nutrients to supply energy and to build new structures
1.1.5	Living organisms control their internal environment
1.1.6	Living organisms interact with one another
1.1.7	Discoveries in biology can be generalized

» Activity 1.1

1.2	How Is All Life on Earth Related?

1.2.1	Life arose from nonlife via chemical evolution
1.2.2	Biological evolution began when cells formed
1.2.3	Photosynthesis changed the course of evolution
1.2.4	Eukaryotic cells evolved from prokaryotes
1.2.5	Multicellularity arose and cells became specialized
1.2.6	Biologists can trace the evolutionary Tree of Life

» Activity 1.2

1.3	How Do Biologists Investigate Life?

1.3.1	Observation is an important skill
1.3.2	The scientific method combines observation and logic
1.3.3	Good experiments have the potential of falsifying hypotheses
1.3.4	Statistical methods are essential scientific tools
1.3.5	Not all forms of inquiry are scientific

1.4	How Does Biology Influence Public Policy?

Chapter Summary

» Flashcards 1

» Online Quiz 1

» Suggested Readings 1

» Key Terms 1

» Experiment Links 1

» Interactive Summary 1

» Interactive Quiz 1

» Resource Table of Contents

» Notes

For Discussion

For Investigation

2	The Chemistry of Life

Where there is water, there can be life

2.1	What Are the Chemical Elements That Make Up Living Organisms?

2.1.1	An element consists of only one kind of atom
2.1.2	Protons: Their number identifies an element
2.1.3	Neutrons: Their number differs among isotopes
2.1.4	Electrons: Their behavior determines chemical bonding

» Activity 2.1

2.2	How Do Atoms Bond to Form Molecules?

2.2.1	Covalent bonds consist of shared pairs of electrons
2.2.2	Multiple covalent bonds
2.2.3	Ionic bonds form by electrical attraction
2.2.4	Hydrogen bonds may form within or between molecules with polar covalent bonds
2.2.5	Polar and nonpolar substances: Each interacts best with its own kind

» Animated Tutorial 2.1

2.3	How Do Atoms Change Partners in Chemical Reactions?

2.4	What Properties of Water Make It So Important in Biology?

2.4.1	Water has a unique structure and special properties
2.4.2	Water is the solvent of life
2.4.3	Aqueous solutions may be acidic or basic
2.4.4	pH is the measure of hydrogen ion concentration
2.4.5	Buffers minimize pH change
2.4.6	Life’s chemistry began in water

2.5	An Overview and a Preview

Chapter Summary

» Flashcards 2.1

» Flashcards 2.2

» Online Quiz 2

» Suggested Readings 2

» Key Terms 2

» Experiment Links 2

» Interactive Summary 2

» Interactive Quiz 2

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

3	Macromolecules and the Origin of Life

How sweet it is

3.1	What Kinds of Molecules Characterize Living Things?

3.1.1	Functional groups give specific properties to molecules
3.1.2	Isomers have different arrangements of the same atoms
3.1.3	The structures of macromolecules reflect their functions
3.1.4	Most macromolecules are formed by condensation and broken down by hydrolysis

» Animated Tutorial 3.1

» Activity 3.1

3.2	What Are the Chemical Structures and Functions of Proteins?

3.2.1	Amino acids are the building blocks of proteins
3.2.2	Peptide bonds form the backbone of a protein
3.2.3	The primary structure of a protein is its amino acid sequence
3.2.4	The secondary structure of a protein requires hydrogen bonding
3.2.5	The tertiary structure of a protein is formed by bending and folding
3.2.6	The quaternary structure of a protein consists of subunits
3.2.7	Both shape and surface chemistry contribute to protein specificity
3.2.8	Environmental conditions affect protein structure
3.2.9	Chaperonins help shape proteins

» Activity 3.2

3.3	What Are the Chemical Structures and Functions of Carbohydrates?

3.3.1	Monosaccharides are simple sugars
3.3.2	Glycosidic linkages bond monosaccharides
3.3.3	Polysaccharides store energy and provide structural materials
3.3.4	Chemically modified carbohydrates contain additional functional groups

» Activity 3.3

3.4	What Are the Chemical Structures and Functions of Lipids?

3.4.1	Fats and oils store energy
3.4.2	Phospholipids form biological membranes
3.4.3	Not all lipids are triglycerides

3.5	What Are the Chemical Structures and Functions of Nucleic Acids?

3.5.1	Nucleotides are the building blocks of nucleic acids
3.5.2	The uniqueness of a nucleic acid resides in its nucleotide sequence
3.5.3	DNA reveals evolutionary relationships
3.5.4	Nucleotides have other important roles

» Activity 3.4

» Activity 3.5

3.6	How Did Life on Earth Begin?

3.6.1	Could life have come from outside Earth?
3.6.2	Did life originate on Earth?
3.6.3	Chemical evolution may have led to polymerization
3.6.4	RNA may have been the first biological catalyst
3.6.5	Experiments disproved spontaneous generation of life

» Animated Tutorial 3.2

» Animated Tutorial 3.3

Chapter Summary

» Flashcards 3.1

» Flashcards 3.2

» Flashcards 3.3

» Online Quiz 3

» Suggested Readings 3

» Key Terms 3

» Experiment Links 3

» Interactive Summary 3

» Interactive Quiz 3

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

4	Cells: The Working Units of Life

The oldest evidence of life?

4.1	What Features of Cells Make Them the Fundamental Unit of Life?

4.1.1	Cell size is limited by the surface area-to-volume ratio
4.1.2	Microscopes are needed to visualize cells
4.1.3	Cells are surrounded by a plasma membrane
4.1.4	Cells are prokaryotic or eukaryotic

» Activity 4.1

» Activity 4.2

4.2	What Are the Characteristics of Prokaryotic Cells?

4.2.1	Prokaryotic cells share certain features
4.2.2	Some prokaryotic cells have specialized features

4.3	What Are the Characteristics of Eukaryotic Cells?

4.3.1	Compartmentalization is the key to eukaryotic cell function
4.3.2	Organelles can be studied by microscopy or isolated for chemical analysis
4.3.3	Some organelles process information
4.3.4	The endomembrane system is a group of interrelated organelles
4.3.5	Some organelles transform energy
4.3.6	Several other organelles are surrounded by a membrane
4.3.7	The cytoskeleton is important in cell structure

» Animated Tutorial 4.1

» Animated Tutorial 4.2

» Activity 4.3

4.4	What Are the Roles of Extracellular Structures?

4.4.1	The plant cell wall is an extracellular structure
4.4.2	The extracellular matrix supports tissue functions in animals

4.5	How Did Eukaryotic Cells Originate?

4.5.1	The endosymbiosis theory suggests how eukaryotes evolved
4.5.2	Both prokaryotes and eukaryotes continue to evolve

Chapter Summary

» Flashcards 4.1

» Flashcards 4.2

» Online Quiz 4

» Suggested Readings 4

» Key Terms 4

» Experiment Links 4

» Interactive Summary 4

» Interactive Quiz 4

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

5	The Dynamic Cell Membrane

Disaster at the plasma membrane

5.1	What Is the Structure of a Biological Membrane?

5.1.1	Lipids constitute the bulk of a membrane
5.1.2	Membrane proteins are asymmetrically distributed
5.1.3	Membranes are dynamic
5.1.4	Membrane carbohydrates are recognition sites

» Activity 5.1

5.2	How Is the Plasma Membrane Involved in Cell Adhesion and Recognition?

5.2.1	Cell recognition and cell adhesion involve proteins at the cell surface
5.2.2	Three types of cell junctions connect adjacent cells

» Activity 5.2

5.3	What Are the Passive Processes of Membrane Transport?

5.3.1	Diffusion is the process of random movement toward a state of equilibrium
5.3.2	Simple diffusion takes place through the phospholipid bilayer
5.3.3	Osmosis is the diffusion of water across membranes
5.3.4	Diffusion may be aided by channel proteins
5.3.5	Carrier proteins aid diffusion by binding substances

» Animated Tutorial 5.1

5.4	How Do Substances Cross Membranes against a Concentration Gradient?

5.4.1	Active transport is directional
5.4.2	Primary and secondary active transport rely on different energy sources

» Animated Tutorial 5.2

5.5	How Do Large Molecules Enter and Leave a Cell?

5.5.1	Macromolecules and particles enter the cell by endocytosis
5.5.2	Receptor-mediated endocytosis is highly specific
5.5.3	Exocytosis moves materials out of the cell

» Animated Tutorial 5.3

5.6	What Are Some Other Functions of Membranes?

Chapter Summary

» Flashcards 5.1

» Flashcards 5.2

» Online Quiz 5

» Suggested Readings 5

» Key Terms 5

» Experiment Links 5

» Interactive Summary 5

» Interactive Quiz 5

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

6	Energy, Enzymes, and Metabolism

Sensitivity to alcohol

6.1	What Physical Principles Underlie Biological Energy Transformations?

6.1.1	There are two basic types of energy and of metabolism
6.1.2	The first law of thermodynamics: Energy is neither created nor destroyed
6.1.3	The second law of thermodynamics: Disorder tends to increase
6.1.4	Chemical reactions release or consume energy
6.1.5	Chemical equilibrium and free energy are related

6.2	What Is the Role of ATP in Biochemical Energetics?

6.2.1	ATP hydrolysis releases energy
6.2.2	ATP couples exergonic and endergonic reactions

» Activity 6.1

6.3	What Are Enzymes?

6.3.1	For a reaction to proceed, an energy barrier must be overcome
6.3.2	Enzymes bind specific reactant molecules
6.3.3	Enzymes lower the energy barrier but do not affect equilibrium

» Activity 6.2

6.4	How Do Enzymes Work?

6.4.1	Molecular structure determines enzyme function
6.4.2	Some enzymes require other molecules in order to function
6.4.3	Substrate concentration affects reaction rate

6.5	How Are Enzyme Activities Regulated?

6.5.1	Enzymes can be regulated by inhibitors
6.5.2	Allosteric enzymes control their activity by changing their shape
6.5.3	Allosteric effects regulate metabolism
6.5.4	Enzymes are affected by their environment

» Animated Tutorial 6.1

» Animated Tutorial 6.2

Chapter Summary

» Flashcards 6.1

» Flashcards 6.2

» Online Quiz 6

» Suggested Readings 6

» Key Terms 6

» Experiment Links 6

» Interactive Summary 6

» Interactive Quiz 6

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

7	Pathways That Harvest Chemical Energy

Of mice and marathons

7.1	How Does Glucose Oxidation Release Chemical Energy?

7.1.1	Cells trap free energy while metabolizing glucose
7.1.2	An overview: Harvesting energy from glucose
7.1.3	Redox reactions transfer electrons and energy
7.1.4	The coenzyme NAD is a key electron carrier in redox reactions

» Activity 7.1

» Activity 7.2

7.2	What Are the Aerobic Pathways of Glucose Metabolism?

7.2.1	The energy-investing reactions of glycolysis require ATP
7.2.2	The energy-harvesting reactions of glycolysis yield NADH + H⁺ and ATP
7.2.3	Pyruvate oxidation links glycolysis and the citric acid cycle
7.2.4	The citric acid cycle completes the oxidation of glucose to CO₂
7.2.5	The citric acid cycle is regulated by concentrations of starting materials

» Activity 7.3

7.3	How Is Energy Harvested from Glucose in the Absence of Oxygen?

7.4	How Does the Oxidation of Glucose Form ATP?

7.4.1	The electron transport chain shuttles electrons and releases energy
7.4.2	Proton diffusion is coupled to ATP synthesis

» Activity 7.4

» Animated Tutorial 7.1

» Animated Tutorial 7.2

7.5	Why Does Cellular Respiration Yield So Much More Energy Than Fermentation?

7.6	How Are Metabolic Pathways Interrelated and Controlled?

7.6.1	Catabolism and anabolism involve interconversions of biological monomers
7.6.2	Catabolism and anabolism are integrated
7.6.3	Metabolic pathways are regulated systems

» Activity 7.5

» Activity 7.6

Chapter Summary

» Flashcards 7

» Online Quiz 7

» Suggested Readings 7

» Key Terms 7

» Experiment Links 7

» Interactive Summary 7

» Interactive Quiz 7

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

8	Photosynthesis: Energy from Sunlight

The ultimate energy source

8.1	What Is Photosynthesis?

8.1.1

Photosynthesis involves two pathways

» Animated Tutorial 8.1

8.2	How Does Photosynthesis Convert Light Energy into Chemical Energy?

8.2.1	Light behaves as both a particle and a wave
8.2.2	Absorbing a photon excites a pigment molecule
8.2.3	Absorbed wavelengths correlate with biological activity
8.2.4	Photosynthesis uses energy absorbed by several pigments
8.2.5	Light absorption results in photochemical change
8.2.6	Excited chlorophyll in the reaction center acts as a reducing agent
8.2.7	Reduction leads to electron transport
8.2.8	Noncyclic electron transport produces ATP and NADPH
8.2.9	Cyclic electron transport produces ATP but no NADPH
8.2.10	Chemiosmosis is the source of the ATP produced in photophosphorylation

» Animated Tutorial 8.2

8.3	How Is Chemical Energy Used to Synthesize Carbohydrates?

8.3.1	Radioisotope labeling experiments revealed the steps of the Calvin cycle
8.3.2	The Calvin cycle is made up of three processes
8.3.3	Light stimulates the Calvin cycle

» Animated Tutorial 8.3

» Activity 8.1

8.4	How Do Plants Adapt to the Inefficiencies of Photosynthesis?

8.4.1	Rubisco catalyzes RuBP reaction with O₂ as well as with CO₂
8.4.2	C₄ plants can bypass photorespiration
8.4.3	CAM plants also use PEP carboxylase

» Activity 8.2

8.5	How Is Photosynthesis Connected to Other Metabolic Pathways in Plants?

Chapter Summary

» Flashcards 8.1

» Flashcards 8.2

» Online Quiz 8

» Suggested Readings 8

» Key Terms 8

» Experiment Links 8

» Interactive Summary 8

» Interactive Quiz 8

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

9	Chromosomes, the Cell Cycle, and Cell Division

The immortal cells of Henrietta Lacks

9.1	How Do Prokaryotic and Eukaryotic Cells Divide?

9.1.1	Prokaryotes divide by binary fission
9.1.2	Eukaryotic cells divide by mitosis or meiosis

9.2	How Is Eukaryotic Cell Division Controlled?

9.2.1	Cyclins and other proteins trigger events in the cell cycle
9.2.2	Growth factors can stimulate cells to divide

9.3	What Happens during Mitosis?

9.3.1	Eukaryotic DNA is packed into very compact chromosomes
9.3.2	Overview: Mitosis segregates exact copies of genetic information
9.3.3	The centrosomes determine the plane of cell division
9.3.4	Chromatids become visible and the spindle forms during prophase
9.3.5	Chromosome movements are highly organized
9.3.6	Nuclei re-form during telophase
9.3.7	Cytokinesis is the division of the cytoplasm

» Animated Tutorial 9.1

» Activity 9.1

» Activity 9.2

9.4	What Is the Role of Cell Division in Sexual Life Cycles?

9.4.1	Reproduction by mitosis results in genetic constancy
9.4.2	Reproduction by meiosis results in genetic diversity
9.4.3	The number, shapes, and sizes of the metaphase chromosomes constitute the karyotype

» Activity 9.3

9.5	What Happens When a Cell Undergoes Meiosis?

9.5.1	The first meiotic division reduces the chromosome number
9.5.2	The second meiotic division separates the chromatids
9.5.3	The activities and movements of chromosomes during meiosis result in genetic diversity
9.5.4	Meiotic errors lead to abnormal chromosome structures and numbers
9.5.5	Polyploids can have difficulty in cell division

» Animated Tutorial 9.2

» Activity 9.4

9.6	How Do Cells Die?

Chapter Summary

» Flashcards 9.1

» Flashcards 9.2

» Flashcards 9.3

» Online Quiz 9

» Suggested Readings 9

» Key Terms 9

» Experiment Links 9

» Interactive Summary 9

» Interactive Quiz 9

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

10	Genetics: Mendel and Beyond

The wisdom of the rabbis

10.1	What Are the Mendelian Laws of Inheritance?

10.1.1	Mendel brought new methods to experiments on inheritance
10.1.2	Mendel devised a careful research plan
10.1.3	Mendel’s first experiments involved monohybrid crosses
10.1.4	Alleles are different forms of a gene
10.1.5	Mendel’s first law says that the two copies of a gene segregate
10.1.6	Mendel verified his hypothesis by performing a test cross
10.1.7	Mendel’s second law says that copies of different genes assort independently
10.1.8	Punnett squares or probability calculations: A choice of methods
10.1.9	Mendel’s laws can be observed in human pedigrees

» Activity 10.1

» Animated Tutorial 10.1

10.2	How Do Alleles Interact?

10.2.1	New alleles arise by mutation
10.2.2	Many genes have multiple alleles
10.2.3	Dominance is not always complete
10.2.4	In codominance, both alleles at a locus are expressed
10.2.5	Some alleles have multiple phenotypic effects

10.3	How Do Genes Interact?

10.3.1	Hybrid vigor results from new gene combinations and interactions
10.3.2	The environment affects gene action
10.3.3	Most complex phenotypes are determined by multiple genes and the environment

10.4	What Is the Relationship between Genes and Chromosomes?

10.4.1	Genes on the same chromosome are linked
10.4.2	Genes can be exchanged between chromatids
10.4.3	Geneticists can make maps of chromosomes
10.4.4	Linkage is revealed by studies of the sex chromosomes
10.4.5	Genes on sex chromosomes are inherited in special ways
10.4.6	Humans display many sex-linked characters

» Animated Tutorial 10.2

10.5	What Are the Effects of Genes Outside the Nucleus?

Chapter Summary

» Activity 10.2

» Activity 10.3

» Flashcards 10.1

» Flashcards 10.2

» Online Quiz 10

» Suggested Readings 10

» Key Terms 10

» Experiment Links 10

» Interactive Summary 10

» Interactive Quiz 10

» Resource Table of Contents

» Notes

11	DNA and Its Role in Heredity

A structure for our times

11.1	What Is the Evidence that the Gene is DNA?

11.1.1	DNA from one type of bacterium genetically transforms another type
11.1.2	The transforming principle is DNA
11.1.3	Viral replication experiments confirmed that DNA is the genetic material
11.1.4	Eukaryotic cells can also be genetically transformed by DNA

11.2	What Is the Structure of DNA?

11.2.1	The chemical composition of DNA was known
11.2.2	Watson and Crick described the double helix
11.2.3	Four key features define DNA structure
11.2.4	The double-helical structure of DNA is essential to its function

11.3	How Is DNA Replicated?

11.3.1	Three modes of DNA replication appeared possible
11.3.2	Meselson and Stahl demonstrated that DNA replication is semiconservative
11.3.3	There are two steps in DNA replication
11.3.4	DNA is threaded through a replication complex
11.3.5	DNA polymerases add nucleotides to the growing chain
11.3.6	Telomeres are not fully replicated

» Animated Tutorial 11.1

» Animated Tutorial 11.2

» Animated Tutorial 11.3

11.4	How Are Errors in DNA Repaired?

11.5	What Are Some Applications of Our Knowledge of DNA Structure and Replication?

11.5.1	The polymerase chain reaction makes multiple copies of DNA
11.5.2	The nucleotide sequence of DNA can be determined

Chapter Summary

» Flashcards 11.1

» Flashcards 11.2

» Online Quiz 11

» Suggested Readings 11

» Key Terms 11

» Experiment Links 11

» Interactive Summary 11

» Interactive Quiz 11

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

12	From DNA to Protein: Genotype to Phenotype

Toxic avenger at the ribosome

12.1	What Is the Evidence that Genes Code for Proteins?

12.1.1	Experiments on bread mold established that genes determine enzymes
12.1.2	One gene determines one polypeptide

12.2	How Does Information Flow from Genes to Proteins?

12.2.1	RNA differs from DNA
12.2.2	Information flows in one direction when genes are expressed
12.2.3	RNA viruses are exceptions to the central dogma

12.3	How Is the Information Content in DNA Transcribed to Produce RNA?

12.3.1	RNA polymerases share common features
12.3.2	Transcription occurs in three steps
12.3.3	The information for protein synthesis lies in the genetic code
12.3.4	Biologists used artificial messengers to decipher the genetic code

» Animated Tutorial 12.2

» Animated Tutorial 12.1

» Activity 12.1

» Animated Tutorial 12.2

12.4	How Is RNA Translated into Proteins?

12.4.1	Transfer RNAs carry specific amino acids and bind to specific codons
12.4.2	Activating enzymes link the right tRNAs and amino acids
12.4.3	The ribosome is the workbench for translation
12.4.4	Translation takes place in three steps
12.4.5	Polysome formation increases the rate of protein synthesis

» Animated Tutorial 12.3

12.5	What Happens to Polypeptides after Translation?

12.5.1	Signal sequences in proteins direct them to their cellular destinations
12.5.2	Many proteins are modified after translation

12.6	What Are Mutations?

12.6.1	Point mutations change single nucleotides
12.6.2	Chromosomal mutations are extensive changes in the genetic material
12.6.3	Mutations can be spontaneous or induced
12.6.4	Mutations are the raw material of evolution

Chapter Summary

» Flashcards 12.1

» Flashcards 12.2

» Online Quiz 12

» Suggested Readings 12

» Key Terms 12

» Experiment Links 12

» Interactive Summary 12

» Interactive Quiz 12

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

13	The Genetics of Viruses and Prokaryotes

Mutation of a bird virus results in human infection

13.1	How Do Viruses Reproduce and Transmit Genes?

13.1.1	Viruses are not cells
13.1.2	Viruses reproduce only with the help of living cells
13.1.3	Bacteriophage reproduce by a lytic cycle or a lysogenic cycle
13.1.4	Animal viruses have diverse reproductive cycles
13.1.5	Many plant viruses spread with the help of vectors

13.2	How Is Gene Expression Regulated in Viruses?

13.3	How Do Prokaryotes Exchange Genes?

13.3.1	The reproduction of prokaryotes gives rise to clones
13.3.2	Bacteria have several ways of recombining their genes
13.3.3	Plasmids are extra chromosomes in bacteria
13.3.4	Transposable elements move genes among plasmids and chromosomes

13.4	How Is Gene Expression Regulated in Prokaryotes?

13.4.1	Regulating gene transcription conserves energy
13.4.2	A single promoter can control the transcription of adjacent genes
13.4.3	Operons are units of transcription in prokaryotes
13.4.4	Operator–repressor control induces transcription in the lac operon
13.4.5	Operator–repressor control represses transcription in the trp operon
13.4.6	Protein synthesis can be controlled by increasing promoter efficiency

» Animated Tutorial 13.1

» Animated Tutorial 13.2

13.5	What Have We Learned from the Sequencing of Prokaryotic Genomes?

13.5.1	The sequencing of prokaryotic genomes has many potential benefits
13.5.2	Will defining the genes required for cellular life lead to artificial life?

Chapter Summary

» Activity 13.1

» Flashcards 13.1

» Flashcards 13.2

» Online Quiz 13

» Suggested Readings 13

» Key Terms 13

» Experiment Links 13

» Interactive Summary 13

» Interactive Quiz 13

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

14	The Eukaryotic Genome and Its Expression

Endangered genomes

14.1	What Are the Characteristics of the Eukaryotic Genome?

14.1.1	Model organisms reveal the characteristics of eukaryotic genomes
14.1.2	Eukaryotic genomes contain many repetitive sequences

» Activity 14.1

14.2	What Are the Characteristics of Eukaryotic Genes?

14.2.1	Protein-coding genes contain noncoding sequences
14.2.2	Gene families are important in evolution and cell specialization

14.3	How Are Eukaryotic Gene Transcripts Processed?

14.3.1	The primary transcript of a protein-coding gene is modified at both ends
14.3.2	Splicing removes introns from the primary transcript

» Animated Tutorial 14.1

14.4	How Is Eukaryotic Gene Transcription Regulated?

14.4.1	Specific genes can be selectively transcribed
14.4.2	Gene expression can be regulated by changes in chromatin structure
14.4.3	Selective gene amplification results in more templates for transcription

» Activity 14.2

» Animated Tutorial 14.2

14.5	How Is Eukaryotic Gene Expression Regulated After Transcription?

14.5.1	Different mRNAs can be made from the same gene by alternative splicing
14.5.2	The stability of mRNA can be regulated
14.5.3	Small RNAs can break down mRNAs
14.5.4	RNA can be edited to change the encoded protein

14.6	How Is Gene Expression Controlled During and After Translation?

14.6.1	The initiation and extent of translation can be regulated
14.6.2	Posttranslational controls regulate the longevity of proteins

Chapter Summary

» Flashcards 14

» Online Quiz 14

» Suggested Readings 14

» Key Terms 14

» Experiment Links 14

» Interactive Summary 14

» Interactive Quiz 14

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

15	Cell Signaling and Communication

Have a cup of signals

15.1	What Are Signals, and How Do Cells Respond to Them?

15.1.1	Cells receive signals from the physical environment and from other cells
15.1.2	A signal transduction pathway involves a signal, a receptor, transduction, and effects

» Activity 15.1

15.2	How Do Signal Receptors Initiate a Cellular Response?

15.2.1	Receptors have specific binding sites for their signals
15.2.2	Receptors can be classified by location

» Animated Tutorial 15.1

15.3	How Is a Response to a Signal Transduced through the Cell?

15.3.1	Protein kinase cascades amplify a response to ligand binding
15.3.2	Second messengers can stimulate protein kinase cascades
15.3.3	Second messengers can be derived from lipids
15.3.4	Calcium ions are involved in many signal transduction pathways
15.3.5	Nitric oxide can act as a second messenger
15.3.6	Signal transduction is highly regulated

15.4	How Do Cells Change in Response to Signals?

15.4.1	Ion channels open in response to signals
15.4.2	Enzyme activities change in response to signals
15.4.3	Signals can initiate gene transcription

15.5	How Do Cells Communicate Directly?

15.5.1	Animal cells communicate by gap junctions
15.5.2	Plant cells communicate by plasmodesmata

Chapter Summary

» Activity 15.2

» Flashcards 15

» Online Quiz 15

» Suggested Readings 15

» Key Terms 15

» Experiment Links 15

» Interactive Summary 15

» Interactive Quiz 15

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

16	Recombinant DNA and Biotechnology

Baby 81

16.1	How Are Large DNA Molecules Analyzed?

16.1.1	Restriction enzymes cleave DNA at specific sequences
16.1.2	Gel electrophoresis separates DNA fragments
16.1.3	DNA fingerprinting uses restriction analysis and electrophoresis
16.1.4	The DNA barcode project aims to identify all organisms on Earth

» Animated Tutorial 16.1

16.2	What Is Recombinant DNA?

16.3	How Are New Genes Inserted into Cells?

16.3.1	Genes can be inserted into prokaryotic or eukaryotic cells
16.3.2	Vectors carry new DNA into host cells
16.3.3	Reporter genes identify host cells containing recombinant DNA

16.4	What Are the Sources of DNA Used in Cloning?

16.4.1	Gene libraries provide collections of DNA fragments
16.4.2	cDNA libraries are constructed from mRNA transcripts
16.4.3	DNA can be synthesized chemically in the laboratory
16.4.4	DNA mutations can be created in the laboratory

16.5	What Other Tools Are Used to Manipulate DNA?

16.5.1	Genes can be inactivated by homologous recombination
16.5.2	Antisense RNA and interference RNA can prevent the expression of specific genes
16.5.3	DNA chips can reveal DNA mutations and RNA expression

» Animated Tutorial 16.2

16.6	What Is Biotechnology?

16.6.1	Expression vectors can turn cells into protein factories
16.6.2	Medically useful proteins can be made by biotechnology
16.6.3	DNA manipulation is changing agriculture
16.6.4	There is public concern about biotechnology

» Activity 16.1

Chapter Summary

» Flashcards 16

» Online Quiz 16

» Suggested Readings 16

» Key Terms 16

» Experiment Links 16

» Interactive Summary 16

» Interactive Quiz 16

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

17	Genome Sequencing, Molecular Biology, and Medicine

Genomes of the founders of Quebec

17.1	How Do Defective Proteins Lead to Diseases?

17.1.1	Genetic mutations may make proteins dysfunctional
17.1.2	Prion diseases are disorders of protein conformation
17.1.3	Most diseases are caused by both genes and environment
17.1.4	Human genetic diseases have several patterns of inheritance

17.2	What Kinds of DNA Changes Lead to Diseases?

17.2.1	One way to identify a gene is to start with its protein
17.2.2	Chromosome deletions can lead to gene and then protein isolation
17.2.3	Genetic markers can point the way to important genes
17.2.4	Disease-causing mutations may involve any number of base pairs
17.2.5	Expanding triplet repeats demonstrate the fragility of some human genes
17.2.6	DNA changes in males and females can have different consequences

» Activity 17.1

17.3	How Does Genetic Screening Detect Diseases?

17.3.1	Screening for disease phenotypes can make use of protein expression
17.3.2	DNA testing is the most accurate way to detect abnormal genes

» Animated Tutorial 17.1

17.4	What Is Cancer?

17.4.1	Cancer cells differ from their normal counterparts
17.4.2	Some cancers are caused by viruses
17.4.3	Most cancers are caused by genetic mutations
17.4.4	Two kinds of genes are changed in many cancers
17.4.5	Several events must occur to turn a normal cell into a malignant cell

17.5	How Are Genetic Diseases Treated?

17.5.1	Genetic diseases can be treated by modifying the phenotype
17.5.2	Gene therapy offers the hope of specific treatments

17.6	What Have We Learned from the Human Genome Project?

17.6.1	There are two approaches to genome sequencing
17.6.2	The sequence of the human genome contained many surprises
17.6.3	The human genome sequence has many applications
17.6.4	The use of genetic information poses ethical questions
17.6.5	The proteome is more complex than the genome
17.6.6	Systems biology integrates data from genomics and proteomics

» Animated Tutorial 17.2

Chapter Summary

» Activity 17.2

» Flashcards 17

» Online Quiz 17

» Suggested Readings 17

» Key Terms 17

» Experiment Links 17

» Interactive Summary 17

» Interactive Quiz 17

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

18	Immunology: Gene Expression and Natural Defense Systems

The most dangerous foe

18.1	What Are the Major Defense Systems of Animals?

18.1.1	Blood and lymph tissues play important roles in defense systems
18.1.2	White blood cells play many defensive roles
18.1.3	Immune system proteins bind pathogens or signal other cells

» Activity 18.1

» Animated Tutorial 18.1

18.2	What Are the Characteristics of the Nonspecific Defenses?

18.2.1	Barriers and local agents defend the body against invaders
18.2.2	Other nonspecific defenses include specialized proteins and cellular processes
18.2.3	Inflammation is a coordinated response to infection or injury
18.2.4	A cell signaling pathway stimulates the body’s defenses

» Activity 18.2

18.3	How Does Specific Immunity Develop?

18.3.1	The specific immune system has four key traits
18.3.2	Two types of specific immune responses interact
18.3.3	Genetic changes and clonal selection generate the specific immune response
18.3.4	Immunity and immunological memory result from clonal selection
18.3.5	Vaccines are an application of immunological memory
18.3.6	Animals distinguish self from nonself and tolerate their own antigens

» Animated Tutorial 18.2

18.4	What Is the Humoral Immune Response?

18.4.1	Some B cells develop into plasma cells
18.4.2	Different antibodies share a common structure
18.4.3	There are five classes of immunoglobulins
18.4.4	Monoclonal antibodies have many uses

» Animated Tutorial 18.3

» Activity 18.3

18.5	What Is the Cellular Immune Response?

18.5.1	T cell receptors are found on two types of T cells
18.5.2	The MHC encodes proteins that present antigens to the immune system
18.5.3	Helper T cells and MHC II proteins contribute to the humoral immune response
18.5.4	Cytotoxic T cells and MHC I proteins contribute to the cellular immune response
18.5.5	MHC proteins underlie the tolerance of self

» Animated Tutorial 18.4

18.6	How Do Animals Make So Many Different Antibodies?

18.6.1	Antibody diversity results from DNA rearrangement and other mutations
18.6.2	The constant region is involved in class switching

» Animated Tutorial 18.5

18.7	What Happens When the Immune System Malfunctions?

18.7.1	Allergic reactions result from hypersensitivity
18.7.2	Autoimmune diseases are caused by reactions against self antigens
18.7.3	AIDS is an immune deficiency disorder

Chapter Summary

» Flashcards 18.1

» Flashcards 18.2

» Online Quiz 18

» Suggested Readings 18

» Key Terms 18

» Experiment Links 18

» Interactive Summary 18

» Interactive Quiz 18

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

19	Differential Gene Expression in Development

Stem cells from fat

19.1	What Are the Processes of Development?

19.1.1	Development proceeds via determination, differentiation, morphogenesis, and growth
19.1.2	Cell fates become more and more restricted

19.2	Is Cell Differentiation Irreversible?

19.2.1	Plant cells are usually totipotent
19.2.2	Among animals, the cells of early embryos are totipotent
19.2.3	The somatic cells of adult animals retain the complete genome
19.2.4	Pluripotent stem cells can be induced to differentiate by environmental signals
19.2.5	Embryonic stem cells are potentially powerful therapeutic agents

» Animated Tutorial 19.1

19.3	What Is the Role of Gene Expression in Cell Differentiation?

19.3.1	Differential gene transcription is a hallmark of cell differentiation
19.3.2	Tools of molecular biology are used to investigate development

19.4	How Is Cell Fate Determined?

19.4.1	Cytoplasmic segregation can determine polarity and cell fate
19.4.2	Inducers passing from one cell to another can determine cell fates

» Animated Tutorial 19.2

19.5	How Does Gene Expression Determine Pattern Formation?

19.5.1	Some genes determine programmed cell death during development
19.5.2	Plants have organ identity genes
19.5.3	Morphogen gradients provide positional information
19.5.4	In the fruit fly, a cascade of transcription factors establishes body segmentation
19.5.5	Homeobox-containing genes encode transcription factors

» Animated Tutorial 19.3

Chapter Summary

» Flashcards 19

» Online Quiz 19

» Suggested Readings 19

» Key Terms 19

» Experiment Links 19

» Interactive Summary 19

» Interactive Quiz 19

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

20	Development and Evolutionary Change

The eyes have it

20.1	How Does a Molecular Tool Kit Govern Development?

20.1.1

Developmental genes in diverse organisms are similar, but have different results

20.2	How Can Mutations with Large Effects Change Only One Part of the Body?

20.2.1	Genetic switches govern how the molecular tool kit is used
20.2.2	Modularity allows differences in the timing and spatial pattern of gene expression

» Animated Tutorial 20.1

20.3	How Can Differences among Species Evolve?

20.4	How Does the Environment Modulate Development?

20.4.1	Organisms respond to signals that accurately predict the future
20.4.2	Some signals that accurately predict the future may not always occur
20.4.3	Organisms do not respond to signals that are poorly correlated with future conditions
20.4.4	Organisms may lack appropriate responses to new environmental signals

» Activity 20.1

20.5	How Do Developmental Genes Constrain Evolution?

20.5.1	Evolution proceeds by changing what’s already there
20.5.2	Conserved developmental genes can lead to parallel evolution

Chapter Summary

» Flashcards 20

» Online Quiz 20

» Suggested Readings 20

» Key Terms 20

» Experiment Links 20

» Interactive Summary 20

» Interactive Quiz 20

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

21	The History of Life on Earth

Giant rodents

21.1	How Do Scientists Date Ancient Events?

21.1.1	Radioisotopes provide a way to date rocks
21.1.2	Radioisotope dating methods have been expanded and refined

21.2	How Have Earth’s Continents and Climates Changed over Time?

21.2.1	Oxygen has steadily increased in Earth’s atmosphere
21.2.2	Earth’s climate has shifted between hot/humid and cold/dry conditions
21.2.3	Volcanoes have occasionally changed the history of life
21.2.4	Extraterrestrial events have triggered changes on Earth

» Animated Tutorial 21.1

21.3	What Are the Major Events in Life’s History?

21.3.1	Several processes contribute to the paucity of fossils
21.3.2	Precambrian life was small and aquatic
21.3.3	Life expanded rapidly during the Cambrian period
21.3.4	Many groups of organisms diversified
21.3.5	Geographic differentiation increased during the Mesozoic era
21.3.6	The modern biota evolved during the Cenozoic era
21.3.7	Three major faunas have dominated life on Earth

21.4	Why Do Evolutionary Rates Differ among Groups of Organisms?

21.4.1	“Living fossils” exist today
21.4.2	Evolutionary changes have been gradual in most groups
21.4.3	Rates of evolutionary change are sometimes rapid
21.4.4	Rates of extinction have also varied greatly

Chapter Summary

» Activity 21.1

» Flashcards 21

» Online Quiz 21

» Suggested Readings 21

» Key Terms 21

» Experiment Links 21

» Interactive Summary 21

» Interactive Quiz 21

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

22	The Mechanisms of Evolution

Snake eats poisonous newt—and lives!

22.1	What Facts Form the Base of Our Understanding of Evolution?

22.1.1	Adaptation has two meanings
22.1.2	Population genetics provides an underpinning for Darwin’s theory
22.1.3	Most populations are genetically variable
22.1.4	Evolutionary change can be measured by allele and genotype frequencies
22.1.5	The genetic structure of a population does not change over time if certain conditions exist
22.1.6	Deviations from Hardy–Weinberg equilibrium show that evolution is occurring

» Animated Tutorial 22.1

» Animated Tutorial 22.2

22.2	What Are the Mechanisms of Evolutionary Change?

22.2.1	Mutations generate genetic variation
22.2.2	Gene flow may change allele frequencies
22.2.3	Genetic drift may cause large changes in small populations
22.2.4	Nonrandom mating changes genotype frequencies

22.3	What Evolutionary Mechanisms Result in Adaptation?

22.3.1	Natural selection produces variable results
22.3.2	Sexual selection influences reproductive success

» Animated Tutorial 22.3

22.4	How Is Genetic Variation Maintained within Populations?

22.4.1	Neutral mutations may accumulate within populations
22.4.2	Sexual recombination amplifies the number of possible genotypes
22.4.3	Frequency-dependent selection maintains genetic variation within populations
22.4.4	Environmental variation favors genetic variation
22.4.5	Much genetic variation is maintained in geographically distinct subpopulations

22.5	What Are the Constraints on Evolution?

22.5.1	Developmental processes constrain evolution
22.5.2	Trade-offs constrain evolution
22.5.3	Short-term and long-term evolutionary outcomes sometimes differ

22.6	How Have Humans Influenced Evolution?

Chapter Summary

» Flashcards 22

» Online Quiz 22

» Suggested Readings 22

» Key Terms 22

» Experiment Links 22

» Interactive Summary 22

» Interactive Quiz 22

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

23	Species and Their Formation

Sex stimulates speciation (among other things)

23.1	What Are Species?

23.1.1	We can recognize and identify many species by their appearance
23.1.2	Species form over time

23.2	How Do New Species Arise?

23.2.1	Allopatric speciation requires almost complete genetic isolation
23.2.2	Sympatric speciation occurs without physical barriers

» Animated Tutorial 23.1

» Animated Tutorial 23.2

23.3	What Happens when Newly Formed Species Come Together?

23.3.1	Prezygotic barriers operate before fertilization
23.3.2	Postzygotic barriers operate after fertilization
23.3.3	Hybrid zones may form if reproductive isolation is incomplete

23.4	Why Do Rates of Speciation Vary?

23.5	Why Do Adaptive Radiations Occur?

Chapter Summary

» Activity 23.1

» Flashcards 23

» Online Quiz 23

» Suggested Readings 23

» Key Terms 23

» Experiment Links 23

» Interactive Summary 23

» Interactive Quiz 23

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

24	The Evolution of Genes and Genomes

Molecular evolution and the conquest of polio

24.1	What Can Genomes Reveal about Evolution?

24.1.1	Evolution of genomes results in biological diversity
24.1.2	Genes and proteins are compared through sequence alignment
24.1.3	Models of sequence evolution are used to calculate evolutionary divergence
24.1.4	Experimental studies examine molecular evolution directly

» Activity 24.1

» Activity 24.2

24.2	What Are the Mechanisms of Molecular Evolution?

24.2.1	Much of evolution is neutral
24.2.2	Positive and stabilizing selection can be detected in the genome
24.2.3	Genome size and organization also evolve
24.2.4	New functions can arise by gene duplication
24.2.5	Some gene families evolve through concerted evolution

24.3	What Are Some Applications of Molecular Evolution?

24.3.1	Molecular sequence data are used to determine the evolutionary history of genes
24.3.2	Gene evolution is used to study protein function
24.3.3	In vitro evolution produces new molecules
24.3.4	Molecular evolution is used to study and combat diseases

» Activity 24.3

Chapter Summary

» Flashcards 24

» Online Quiz 24

» Suggested Readings 24

» Key Terms 24

» Experiment Links 24

» Interactive Summary 24

» Interactive Quiz 24

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

25	Reconstructing and Using Phylogenies

Phylogenetic trees in the courtroom

25.1	What Is Phylogeny?

25.1.1	All of life is connected through evolutionary history
25.1.2	Comparisons among species require an evolutionary perspective

25.2	How Are Phylogenetic Trees Constructed?

25.2.1	Parsimony provides the simplest explanation for phylogenetic data
25.2.2	Phylogenies are reconstructed from many sources of data
25.2.3	Mathematical models expand the power of phylogenetic reconstruction
25.2.4	The accuracy of phylogenetic methods can be tested
25.2.5	Ancestral states can be reconstructed
25.2.6	Molecular clocks add a dimension of time

» Activity 25.1

» Animated Tutorial 25.1

25.3	How Do Biologists Use Phylogenetic Trees?

25.3.1	Phylogenies help us reconstruct the past
25.3.2	Phylogenies allow us to compare and contrast living organisms
25.3.3	Biologists use phylogenies to predict the future

25.4	How Does Phylogeny Relate to Classification?

25.4.1	Phylogeny is the basis for modern biological classification
25.4.2	Several codes of biological nomenclature govern the use of scientific names

» Activity 25.2

Chapter Summary

» Flashcards 25

» Online Quiz 25

» Suggested Readings 25

» Key Terms 25

» Experiment Links 25

» Interactive Summary 25

» Interactive Quiz 25

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

26	Bacteria and Archaea: The Prokaryotic Domains

Life on the Red Planet?

26.1	How Did the Living World Begin to Diversify?

26.1.1

The three domains differ in significant ways

» Animated Tutorial 26.1

26.2	Where Are Prokaryotes Found?

26.2.1

Prokaryotes generally form complex communities

26.3	What Are Some Keys to the Success of Prokaryotes?

26.3.1	Prokaryotes have distinctive cell walls
26.3.2	Prokaryotes have distinctive modes of locomotion
26.3.3	Prokaryotes reproduce asexually, but genetic recombination can occur
26.3.4	Some prokaryotes communicate
26.3.5	Prokaryotes have amazingly diverse metabolic pathways

» Activity 26.1

26.4	How Can We Determine Prokaryote Phylogeny?

26.4.1	Size complicates the study of prokaryote phylogeny
26.4.2	The nucleotide sequences of prokaryotes reveal their evolutionary relationships
26.4.3	Lateral gene transfer may complicate phylogenetic studies
26.4.4	The great majority of prokaryote species have never been studied
26.4.5	Mutations are a major source of prokaryotic variation

26.5	What Are the Major Known Groups of Prokaryotes?

26.5.1	Spirochetes move by means of axial filaments
26.5.2	Chlamydias are extremely small parasites
26.5.3	Some high-GC Gram-positives are valuable sources of antibiotics
26.5.4	Cyanobacteria are important photoautotrophs
26.5.5	Not all low-GC Gram-positives are Gram-positive
26.5.6	The Proteobacteria are a large and diverse group
26.5.7	Archaea differ in several important ways from bacteria
26.5.8	Many Crenarchaeota live in hot, acidic places
26.5.9	The Euryarchaeota live in many surprising places
26.5.10	Korarchaeota and Nanoarchaeota are less well known

26.6	How Do Prokaryotes Affect Their Environments?

26.6.1	Prokaryotes are important players in element cycling
26.6.2	Prokaryotes live on and in other organisms
26.6.3	A small minority of bacteria are pathogens

Chapter Summary

» Flashcards 26.1

» Flashcards 26.2

» Online Quiz 26

» Suggested Readings 26

» Key Terms 26

» Experiment Links 26

» Interactive Summary 26

» Interactive Quiz 26

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

27	The Origin and Diversification of the Eukaryotes

A tale of three trypanosomes

27.1	How Do Microbial Eukaryotes Affect the World Around Them?

27.1.1	The phylogeny and morphology of the microbial eukaryotes both illustrate their diversity
27.1.2	Phytoplankton are the primary producers of the marine food web
27.1.3	Some microbial eukaryotes are endosymbionts
27.1.4	Some microbial eukaryotes are deadly
27.1.5	We continue to rely on the products of ancient marine microbial eukaryotes

27.2	How Did the Eukaryotic Cell Arise?

27.2.1	The modern eukaryotic cell arose in several steps
27.2.2	Chloroplasts are a study in endosymbiosis
27.2.3	We cannot yet account for the presence of some prokaryotic genes in eukaryotes

» Animated Tutorial 27.1

27.3	How Did the Microbial Eukaryotes Diversify?

27.3.1	Microbial eukaryotes have different lifestyles
27.3.2	Microbial eukaryotes have diverse means of locomotion
27.3.3	Microbial eukaryotes employ vacuoles in several ways
27.3.4	The cell surfaces of microbial eukaryotes are diverse

» Animated Tutorial 27.2

27.4	How Do Microbial Eukaryotes Reproduce?

27.4.1	Some microbial eukaryotes have reproduction without sex, and sex without reproduction
27.4.2	Many microbial eukaryote life cycles feature alternation of generations
27.4.3	Chlorophytes provide examples of several life cycles
27.4.4	The life cycles of some microbial eukaryotes require more than one host species

» Activity 27.1

» Activity 27.2

27.5	What Are the Major Groups of Eukaryotes?

27.5.1	CHROMALVEOLATES
27.5.2	Alveolates have sacs under their plasma membrane
27.5.3	Stramenopiles have two unequal flagella, one with hairs
27.5.4	PLANTAE
27.5.5	Red algae have a distinctive accessory photosynthetic pigment
27.5.6	Chlorophytes, charophytes, and land plants contain chlorophylls a and b
27.5.7	EXCAVATES
27.5.8	Diplomonads and parabasalids are excavates that lack mitochondria
27.5.9	Heteroloboseans alternate between amoeboid forms and forms with flagella
27.5.10	Euglenids and kinetoplastids have distinctive mitochondria and flagella
27.5.11	RHIZARIA
27.5.12	Foraminiferans have created vast limestone deposits
27.5.13	Radiolarians have thin, stiff pseudopods
27.5.14	UNIKONTS
27.5.15	Amoebozoans use lobe-shaped pseudopods for locomotion

» Activity 27.3

Chapter Summary

» Flashcards 27.1

» Flashcards 27.2

» Online Quiz 27

» Suggested Readings 27

» Key Terms 27

» Experiment Links 27

» Interactive Summary 27

» Interactive Quiz 27

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

28	Plants without Seeds: From Sea to Land

What surprises lurk in a rock?

28.1	How Did the Land Plants Arise?

28.1.1	There are ten major groups of land plants
28.1.2	The land plants arose from a green algal clade

28.2	How Did Plants Colonize and Thrive on Land?

28.2.1	Adaptations to life on land distinguish land plants from green algae
28.2.2	The nonvascular plants usually live where water is available
28.2.3	Life cycles of land plants feature alternation of generations
28.2.4	The sporophytes of nonvascular plants are dependent on gametophytes

» Animated Tutorial 28.1

28.3	What Features Distinguish the Vascular Plants?

28.3.1	Vascular tissues transport water and dissolved materials
28.3.2	Vascular plants have been evolving for almost half a billion years
28.3.3	The earliest vascular plants lacked roots and leaves
28.3.4	The vascular plants branched out
28.3.5	Roots may have evolved from branches
28.3.6	Pteridophytes and seed plants have true leaves
28.3.7	Heterospory appeared among the vascular plants

» Activity 28.1

» Activity 28.2

28.4	What Are the Major Clades of Seedless Plants?

28.4.1	Liverworts may be the most ancient surviving plant clade
28.4.2	Hornworts have stomata, distinctive chloroplasts, and sporophytes without stalks
28.4.3	Water and sugar transport mechanisms emerged in the mosses
28.4.4	Some vascular plants have vascular tissue but not seeds
28.4.5	The club mosses are sister to the other vascular plants
28.4.6	Horsetails, whisk ferns, and ferns constitute a clade

» Activity 28.3

Chapter Summary

» Flashcards 28.1

» Flashcards 28.2

» Online Quiz 28

» Suggested Readings 28

» Key Terms 28

» Experiment Links 28

» Interactive Summary 28

» Interactive Quiz 28

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

29	The Evolution of Seed Plants

A seed from Biblical times germinates in 2005

29.1	How Did Seed Plants Become Today’s Dominant Vegetation?

29.1.1	Features of the seed plant life cycle protect gametes and embryos
29.1.2	The seed is a complex, well-protected package
29.1.3	A change in anatomy enabled seed plants to grow to great heights

29.2	What Are the Major Groups of Gymnosperms?

29.2.1	The relationship between gnetophytes and conifers is a subject of continuing research
29.2.2	Conifers have cones but no motile gametes

» Animated Tutorial 29.1

» Activity 29.1

29.3	What Features Distinguish the Angiosperms?

29.3.1	The sexual structures of angiosperms are flowers
29.3.2	Flower structure has evolved over time
29.3.3	Angiosperms have coevolved with animals
29.3.4	The angiosperm life cycle features double fertilization
29.3.5	Angiosperms produce fruits

» Activity 29.2

» Animated Tutorial 29.2

29.4	How Did the Angiosperms Originate and Diversify?

29.4.1	The basal angiosperm clade is a matter of controversy
29.4.2	The origin of the angiosperms remains a mystery

29.5	How Do Plants Support Our World?

29.5.1	Seed plants are our primary food source
29.5.2	Seed plants have been sources of medicines since ancient times

Chapter Summary

» Flashcards 29.1

» Flashcards 29.2

» Online Quiz 29

» Suggested Readings 29

» Key Terms 29

» Experiment Links 29

» Interactive Summary 29

» Interactive Quiz 29

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

30	Fungi: Recyclers, Pathogens, Parasites, and Plant Partners

A fungus battles witchweed

30.1	How Do Fungi Thrive in Virtually Every Environment?

30.1.1	The body of a multicellular fungus is composed of hyphae
30.1.2	Fungi are in intimate contact with their environment
30.1.3	Fungi exploit many nutrient sources
30.1.4	Fungi balance nutrition and reproduction

» Activity 30.1

30.2	How Are Fungi Beneficial to Other Organisms?

30.2.1	Saprobic fungi dispose of Earth’s garbage and contribute to the planetary carbon cycle
30.2.2	Mutualistic relationships are beneficial to both partners
30.2.3	Lichens can grow where plants cannot
30.2.4	Mycorrhizae are essential to most plants
30.2.5	Endophytic fungi protect some plants from pathogens, herbivores, and stress
30.2.6	Some fungi are food for the ants that farm them

30.3	How Do Fungal Life Cycles Differ from One Another?

30.3.1	Fungi reproduce both sexually and asexually
30.3.2	The dikaryotic condition is unique to the fungi
30.3.3	The life cycles of some parasitic fungi require two hosts
30.3.4	“Imperfect fungi” lack a sexual stage

» Animated Tutorial 30.1

» Activity 30.2

30.4	How Do We Tell the Fungal Groups Apart?

30.4.1	Chytrids are the only fungi with flagella
30.4.2	Zygomycetes reproduce sexually by fusion of two gametangia
30.4.3	Glomeromycetes form arbuscular mycorrhizae
30.4.4	The sexual reproductive structure of ascomycetes is the ascus
30.4.5	The sexual reproductive structure of basidiomycetes is a basidium

Chapter Summary

» Flashcards 30

» Online Quiz 30

» Suggested Readings 30

» Key Terms 30

» Experiment Links 30

» Interactive Summary 30

» Interactive Quiz 30

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

31	Animal Origins and the Evolution of Body Plans

Dinosaur embryos illuminate evolution

31.1	What Evidence Indicates the Animals Are Monophyletic?

31.1.1	Animal monophyly is supported by gene sequences and morphology
31.1.2	Developmental patterns show evolutionary relationships among animals

31.2	What Are the Features of Animal Body Plans?

31.2.1	Most animals are symmetrical
31.2.2	The structure of the body cavity influences movement
31.2.3	Segmentation improves control of movement
31.2.4	Appendages enhance locomotion

31.3	How Do Animals Get Their Food?

31.3.1	Filter feeders capture small prey
31.3.2	Herbivores eat plants
31.3.3	Predators capture and subdue large prey
31.3.4	Parasites live in or on other organisms

31.4	How Do Animal Life Cycles Differ?

31.4.1	All life cycles have at least one dispersal stage
31.4.2	No life cycle can maximize all benefits
31.4.3	Parasite life cycles evolve to facilitate dispersal and overcome host defenses

31.5	What Are the Major Groups of Animals?

31.5.1	Sponges are loosely organized animals
31.5.2	Ctenophores are radially symmetrical and diploblastic
31.5.3	Cnidarians are specialized carnivores

» Animated Tutorial 31.1

Chapter Summary

» Activity 31.1

» Activity 31.2

» Flashcards 31.1

» Flashcards 31.2

» Online Quiz 31

» Suggested Readings 31

» Key Terms 31

» Experiment Links 31

» Interactive Summary 31

» Interactive Quiz 31

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

32	Protostome Animals

Tiny parasites exert mind control

32.1	What Is a Protostome?

32.1.1	Trochophores, lophophores, and spiral cleavage evolved among the lophotrochozoans
32.1.2	Ecdysozoans must shed their exoskeletons
32.1.3	Arrow worms retain some ancestral developmental features

32.2	What Are the Major Groups of Lophotrochozoans?

32.2.1	Ectoprocts live in colonies
32.2.2	Flatworms, rotifers, and ribbon worms are structurally diverse relatives
32.2.3	Phoronids and brachiopods use lophophores to extract food from the water
32.2.4	The annelids and the mollusks are sister groups
32.2.5	Annelids have segmented bodies
32.2.6	Mollusks have undergone a dramatic evolutionary radiation

32.3	What Are the Major Groups of Ecdysozoans?

32.3.1	Several marine groups have relatively few species
32.3.2	Nematodes and their relatives are abundant and diverse

32.4	Why Do Arthropods Dominate Earth’s Fauna?

32.4.1	Arthropod relatives have fleshy, unjointed appendages
32.4.2	Jointed legs first appeared in the trilobites
32.4.3	Crustaceans are diverse and abundant
32.4.4	Insects are the dominant terrestrial arthropods
32.4.5	Myriapods have many legs
32.4.6	Most chelicerates have four pairs of legs

32.5	An Overview of Protostome Evolution

Chapter Summary

» Activity 32.1

» Activity 32.2

» Flashcards 32.1

» Flashcards 32.2

» Online Quiz 32

» Suggested Readings 32

» Key Terms 32

» Experiment Links 32

» Interactive Summary 32

» Interactive Quiz 32

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

33	Deuterostome Animals

Hobbits of Flores Island

33.1	What is a Deuterostome?

33.2	What Are the Major Groups of Echinoderms and Hemichordates?

33.2.1	Echinoderms have a water vascular system
33.2.2	Hemichordates have a three-part body plan

» Activity 33.1

33.3	What New Features Evolved in the Chordates?

33.3.1	Adults of most urochordates and cephalochordates are sessile
33.3.2	A new dorsal supporting structure replaces the notochord in vertebrates
33.3.3	The vertebrate body plan can support large animals
33.3.4	Fins and swim bladders improved stability and control over locomotion

33.4	How Did Vertebrates Colonize the Land?

33.4.1	Jointed fins enhanced support for fishes
33.4.2	Amphibians adapted to life on land
33.4.3	Amniotes colonized dry environments
33.4.4	Reptiles adapted to life in many habitats
33.4.5	Crocodilians and birds share their ancestry with the dinosaurs
33.4.6	The evolution of feathers allowed birds to fly
33.4.7	Mammals radiated after the extinction of dinosaurs
33.4.8	Most mammals are therians

» Animated Tutorial 33.1

» Activity 33.2

33.5	What Traits Characterize the Primates?

33.5.1	Human ancestors evolved bipedal locomotion
33.5.2	Human brains became larger as jaws became smaller
33.5.3	Humans developed complex language and culture

Chapter Summary

» Activity 33.3

» Flashcards 33

» Online Quiz 33

» Suggested Readings 33

» Key Terms 33

» Experiment Links 33

» Interactive Summary 33

» Interactive Quiz 33

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

34	The Plant Body

CSI: Wood anatomy convicts a killer

34.1	How Is the Plant Body Organized?

34.1.1	Roots anchor the plant and take up water and minerals
34.1.2	Stems bear buds, leaves, and flowers
34.1.3	Leaves are the primary sites of photosynthesis
34.1.4	The tissue systems support the plant’s activities

34.2	How Are Plant Cells Unique?

34.2.1	Cell walls may be complex in structure
34.2.2	Parenchyma cells are alive when they perform their functions
34.2.3	Collenchyma cells provide flexible support while alive
34.2.4	Sclerenchyma cells provide rigid support
34.2.5	Cells of the xylem transport water and minerals from roots to stems and leaves
34.2.6	Cells of the phloem translocate carbohydrates and other nutrients

34.3	How Do Meristems Build the Plant Body?

34.3.1	Plants and animals grow differently
34.3.2	A hierarchy of meristems generates a plant’s body
34.3.3	The root apical meristem gives rise to the root cap and the root primary meristems
34.3.4	The products of the root’s primary meristems become root tissues
34.3.5	The products of the stem’s primary meristems become stem tissues
34.3.6	Many eudicot stems and roots undergo secondary growth

» Activity 34.1

» Activity 34.2

» Activity 34.3

» Activity 34.4

» Animated Tutorial 34.1

34.4	How Does Leaf Anatomy Support Photosynthesis?

» Activity 34.5

Chapter Summary

» Flashcards 34.1

» Flashcards 34.2

» Online Quiz 34

» Suggested Readings 34

» Key Terms 34

» Experiment Links 34

» Interactive Summary 34

» Interactive Quiz 34

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

35	Transport in Plants

The curious curate

35.1	How Do Plants Take Up Water and Solutes?

35.1.1	Water moves through a membrane by osmosis
35.1.2	Aquaporins facilitate the movement of water across membranes
35.1.3	Uptake of mineral ions requires membrane transport proteins
35.1.4	Water and ions pass to the xylem by way of the apoplast and symplast

» Activity 35.1

35.2	How Are Water and Minerals Transported in the Xylem?

35.2.1	Experiments ruled out xylem transport by the pumping action of living cells
35.2.2	Root pressure does not account for xylem transport
35.2.3	The transpiration-cohesion-tension mechanism accounts for xylem transport
35.2.4	A pressure chamber measures tension in the xylem sap

35.3	How Do Stomata Control the Loss of Water and the Uptake of CO₂?

35.3.1	The guard cells control the size of the stomatal opening
35.3.2	Transpiration from crops can be decreased

35.4	How Are Substances Translocated in the Phloem?

35.4.1	The pressure flow model appears to account for translocation in the phloem
35.4.2	The pressure flow model has been experimentally tested
35.4.3	Plasmodesmata allow the transfer of material between cells

» Animated Tutorial 35.1

Chapter Summary

» Flashcards 35

» Online Quiz 35

» Suggested Readings 35

» Key Terms 35

» Experiment Links 35

» Interactive Summary 35

» Interactive Quiz 35

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

36	Plant Nutrition

When the land blew away

36.1	How Do Plants Acquire Nutrients?

36.1.1	Autotrophs make their own organic compounds
36.1.2	How does a stationary organism find nutrients?

36.2	What Mineral Nutrients Do Plants Require?

36.2.1	Deficiency symptoms reveal inadequate nutrition
36.2.2	Several essential elements fulfill multiple roles
36.2.3	Experiments were designed to identify essential elements

» Animated Tutorial 36.1

36.3	What Are the Roles of Soil?

36.3.1	Soils are complex in structure
36.3.2	Soils form through the weathering of rock
36.3.3	Soils are the source of plant nutrition
36.3.4	Fertilizers and lime are used in agriculture
36.3.5	Plants affect soil fertility and pH

36.4	How Does Nitrogen Get from Air to Plant Cells?

36.4.1	Nitrogen fixers make all other life possible
36.4.2	Nitrogenase catalyzes nitrogen fixation
36.4.3	Some plants and bacteria work together to fix nitrogen
36.4.4	Biological nitrogen fixation does not always meet agricultural needs
36.4.5	Plants and bacteria participate in the global nitrogen cycle

» Activity 36.1

36.5	Do Soil, Air, and Sunlight Meet the Needs of All Plants?

36.5.1	Carnivorous plants supplement their mineral nutrition
36.5.2	Parasitic plants take advantage of other plants

Chapter Summary

» Flashcards 36

» Online Quiz 36

» Suggested Readings 36

» Key Terms 36

» Experiment Links 36

» Interactive Summary 36

» Interactive Quiz 36

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

37	Regulation Of Plant Growth

More rubber, please

37.1	How Does Plant Development Proceed?

37.1.1	Several hormones and photoreceptors play roles in plant growth regulation
37.1.2	Signal transduction pathways are involved in all stages of plant development
37.1.3	The seed germinates and forms a growing seedling
37.1.4	The plant flowers and sets fruit
37.1.5	The plant senesces and dies
37.1.6	Not all seeds germinate without cues
37.1.7	Seed dormancy affords adaptive advantages
37.1.8	Seed germination begins with the uptake of water
37.1.9	The embryo must mobilize its reserves

» Activity 37.1

» Activity 37.2

37.2	What Do Gibberellins Do?

37.2.1	“Foolish seedling” disease led to the discovery of the gibberellins
37.2.2	The gibberellins have many effects on plant growth and development

» Activity 37.3

37.3	What Does Auxin Do?

37.3.1	Phototropism led to the discovery of auxin
37.3.2	Auxin transport is polar and requires carrier proteins
37.3.3	Light and gravity affect the direction of plant growth
37.3.4	Auxin affects plant growth in several ways
37.3.5	Auxin analogs as herbicides
37.3.6	Auxin promotes growth by acting on cell walls
37.3.7	Auxin and gibberellins are recognized by similar mechanisms

» Animated Tutorial 37.1

» Animated Tutorial 37.2

» Animated Tutorial 37.3

37.4	What Do Cytokinins, Ethylene, Abscisic Acid, and Brassinosteroids Do?

37.4.1	Cytokinins are active from seed to senescence
37.4.2	Ethylene is a gaseous hormone that hastens leaf senescence and fruit ripening
37.4.3	Abscisic acid is the “stress hormone”
37.4.4	Brassinosteroids are hormones that mediate effects of light

37.5	How Do Photoreceptors Participate in Plant Growth Regulation?

37.5.1	Phytochromes mediate the effects of red and far-red light
37.5.2	Phytochromes have many effects on plant growth and development
37.5.3	Multiple phytochromes have different developmental roles
37.5.4	Cryptochromes, phototropins, and zeaxanthin are blue-light receptors

Chapter Summary

» Flashcards 37

» Online Quiz 37

» Suggested Readings 37

» Key Terms 37

» Experiment Links 37

» Interactive Summary 37

» Interactive Quiz 37

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

38	Reproduction In Flowering Plants

Big smelly flowers of Sumatra

38.1	How Do Angiosperms Reproduce Sexually?

38.1.1	The flower is an angiosperm’s structure for sexual reproduction
38.1.2	Flowering plants have microscopic gametophytes
38.1.3	Pollination enables fertilization in the absence of water
38.1.4	Some flowering plants practice “mate selection”
38.1.5	A pollen tube delivers sperm cells to the embryo sac
38.1.6	Angiosperms perform double fertilization
38.1.7	Embryos develop within seeds
38.1.8	Some fruits assist in seed dispersal

» Animated Tutorial 38.1

» Activity 38.1

38.2	What Determines the Transition from the Vegetative to the Flowering State?

38.2.1	Apical meristems can become inflorescence meristems
38.2.2	A cascade of gene expression leads to flowering
38.2.3	Photoperiodic cues can initiate flowering
38.2.4	Plants vary in their responses to different photoperiodic cues
38.2.5	The length of the night is the key photoperiodic cue determining flowering
38.2.6	Circadian rhythms are maintained by a biological clock
38.2.7	Photoreceptors set the biological clock
38.2.8	The flowering stimulus originates in a leaf
38.2.9	In some plants flowering requires a period of low temperature

» Animated Tutorial 38.2

38.3	How Do Angiosperms Reproduce Asexually?

38.3.1	Many forms of asexual reproduction exist
38.3.2	Vegetative reproduction has a disadvantage
38.3.3	Vegetative reproduction is important in agriculture

Chapter Summary

» Flashcards 38

» Online Quiz 38

» Suggested Readings 38

» Key Terms 38

» Experiment Links 38

» Interactive Summary 38

» Interactive Quiz 38

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

39	Plant Responses To Environmental Challenges

Salt in the delta threatens a hungry nation

39.1	How Do Plants Deal with Pathogens?

39.1.1	Plants seal off infected parts to limit damage
39.1.2	Some plants have potent chemical defenses against pathogens
39.1.3	The hypersensitive response is a localized containment strategy
39.1.4	Systemic acquired resistance is a form of long-term “immunity”
39.1.5	Some plant genes match up with pathogen genes
39.1.6	Plants develop specific immunity to RNA viruses

» Animated Tutorial 39.1

39.2	How Do Plants Deal with Herbivores?

39.2.1	Grazing increases the productivity of some plants
39.2.2	Some plants produce chemical defenses against herbivores
39.2.3	Some secondary metabolites play multiple roles
39.2.4	Some plants call for help
39.2.5	Many defenses depend on extensive signaling
39.2.6	Recombinant DNA technology may confer resistance to insects
39.2.7	Why don’t plants poison themselves?
39.2.8	The plant doesn’t always win

39.3	How Do Plants Deal with Climate Extremes?

39.3.1	Some leaves have special adaptations to dry environments
39.3.2	Plants have other adaptations to a limited water supply
39.3.3	In water-saturated soils, oxygen is scarce
39.3.4	Plants have ways of coping with temperature extremes

39.4	How Do Plants Deal with Salt and Heavy Metals?

39.4.1	Most halophytes accumulate salt
39.4.2	Halophytes and xerophytes have some similar adaptations
39.4.3	Some habitats are laden with heavy metals

Chapter Summary

» Activity 39.1

» Flashcards 39

» Online Quiz 39

» Suggested Readings 39

» Key Terms 39

» Experiment Links 39

» Interactive Summary 39

» Interactive Quiz 39

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

40	Physiology, Homeostasis, And Temperature Regulation

Cool it!

40.1	Why Must Animals Regulate Their Internal Environments?

40.1.1	An internal environment makes complex multicellular animals possible
40.1.2	Homeostasis requires physiological regulation
40.1.3	Physiological systems are made up of cells, tissues, and organs
40.1.4	Organs consist of multiple tissues

40.2	How Does Temperature Affect Living Systems?

40.2.1	Q₁₀ is a measure of temperature sensitivity
40.2.2	Animals can acclimatize to a seasonal temperature change

40.3	How Do Animals Alter Their Heat Exchange with the Environment?

40.3.1	How do endotherms produce so much heat?
40.3.2	Ectotherms and endotherms respond differently to changes in temperature
40.3.3	Energy budgets reflect adaptations for regulating body temperature
40.3.4	Both ectotherms and endotherms control blood flow to the skin
40.3.5	Some fish elevate body temperature by conserving metabolic heat
40.3.6	Some ectotherms regulate heat production

40.4	How Do Mammals Regulate Their Body Temperatures?

40.4.1	Basal metabolic rates are correlated with body size and environmental temperature
40.4.2	Endotherms respond to cold by producing heat and reducing heat loss
40.4.3	Evaporation of water can dissipate heat, but at a cost
40.4.4	The vertebrate thermostat uses feedback information
40.4.5	Fever helps the body fight infections
40.4.6	Turning down the thermostat

» Activity 40.1

» Animated Tutorial 40.1

Chapter Summary

» Flashcards 40

» Online Quiz 40

» Suggested Readings 40

» Key Terms 40

» Experiment Links 40

» Interactive Summary 40

» Interactive Quiz 40

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

41	Animal Hormones

Testosterone abuse

41.1	What Are Hormones and How Do They Work?

41.1.1	Hormones can act locally or at a distance
41.1.2	Hormonal communication arose early in evolution
41.1.3	Hormones from the head control molting in insects
41.1.4	Juvenile hormone controls development in insects
41.1.5	Hormones can be divided into three chemical groups
41.1.6	Hormone receptors are found on the cell surface or in the cell interior
41.1.7	Hormone action depends on the nature of the target cell and its receptors

» Animated Tutorial 41.1

41.2	How Do the Nervous and Endocrine Systems Interact?

41.2.1	The pituitary connects nervous and endocrine functions
41.2.2	The anterior pituitary is controlled by hypothalamic hormones
41.2.3	Negative feedback loops control hormone secretion

» Activity 41.1

» Animated Tutorial 41.2

41.3	What Are the Major Mammalian Endocrine Glands and Hormones?

41.3.1	Thyroxine controls cell metabolism
41.3.2	Thyroid dysfunction causes goiter
41.3.3	Calcitonin reduces blood calcium
41.3.4	Parathyroid hormone elevates blood calcium
41.3.5	Vitamin D is really a hormone
41.3.6	PTH lowers blood phosphate levels
41.3.7	Insulin and glucagon regulate blood glucose levels
41.3.8	Somatostatin is a hormone of the brain and the gut
41.3.9	The adrenal gland is two glands in one
41.3.10	The sex steroids are produced by the gonads
41.3.11	Changes in control of sex steroid production initiate puberty
41.3.12	Melatonin is involved in biological rhythms and photoperiodicity
41.3.13	The list of hormones is long

» Animated Tutorial 41.3

41.4	How Do We Study Mechanisms of Hormone Action?

41.4.1	Hormones can be detected and measured with immunoassays
41.4.2	A hormone can act through many receptors
41.4.3	A hormone can act through different signal transduction pathways

Chapter Summary

» Activity 41.2

» Flashcards 41.1

» Flashcards 41.2

» Online Quiz 41

» Suggested Readings 41

» Key Terms 41

» Experiment Links 41

» Interactive Summary 41

» Interactive Quiz 41

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

42	Animal Reproduction

Explosive sex

42.1	How Do Animals Reproduce Without Sex?

42.1.1	Budding and regeneration produce new individuals by mitosis
42.1.2	Parthenogenesis is the development of unfertilized eggs

42.2	How Do Animals Reproduce Sexually?

42.2.1	Gametogenesis produces eggs and sperm
42.2.2	Fertilization is the union of sperm and egg
42.2.3	Mating bring eggs and sperm together
42.2.4	A single body can function as both male and female
42.2.5	The evolution of vertebrate reproductive systems parallels the move to land
42.2.6	Reproductive systems are distinguished by where the embryo develops

» Animated Tutorial 42.1

42.3	How Do the Human Male and Female Reproductive Systems Work?

42.3.1	Male sex organs produce and deliver semen
42.3.2	Male sexual function is controlled by hormones
42.3.3	Female sex organs produce eggs, receive sperm, and nurture the embryo
42.3.4	The ovarian cycle produces a mature egg
42.3.5	The uterine cycle prepares an environment for the fertilized egg
42.3.6	Hormones control and coordinate the ovarian and uterine cycles
42.3.7	In pregnancy, hormones from the extraembryonic membranes take over
42.3.8	Childbirth is triggered by hormonal and mechanical stimuli

» Activity 42.1

» Activity 42.2

» Activity 42.3

» Animated Tutorial 42.2

42.4	How Can Fertility Be Controlled and Sexual Health Maintained?

42.4.1	Human sexual responses have four phases
42.4.2	Humans use a variety of methods to control fertility
42.4.3	Reproductive technologies help solve problems of infertility
42.4.4	Sexual behavior transmits many disease organisms

Chapter Summary

» Flashcards 42.1

» Flashcards 42.2

» Online Quiz 42

» Suggested Readings 42

» Key Terms 42

» Experiment Links 42

» Interactive Summary 42

» Interactive Quiz 42

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

43	Animal Development: From Genes to Organisms

Thar she blows!

43.1	How Does Fertilization Activate Development?

43.1.1	The sperm and the egg make different contributions to the zygote
43.1.2	Rearrangements of egg cytoplasm set the stage for determination
43.1.3	Cleavage repackages the cytoplasm
43.1.4	Cleavage in mammals is unique
43.1.5	Specific blastomeres generate specific tissues and organs

43.2	How Does Gastrulation Generate Multiple Tissue Layers?

43.2.1	Invagination of the vegetal pole characterizes gastrulation in the sea urchin
43.2.2	Gastrulation in the frog begins at the gray crescent
43.2.3	The dorsal lip of the blastopore organizes embryo formation
43.2.4	The molecular mechanisms of the organizer involve multiple transcription factors
43.2.5	The organizer changes its activity as it migrates from the dorsal lip
43.2.6	Reptilian and avian gastrulation is an adaptation to yolky eggs
43.2.7	Placental mammals have no yolk but retain the avian–reptilian gastrulation pattern

» Animated Tutorial 43.1

» Animated Tutorial 43.2

43.3	How Do Organs and Organ Systems Develop?

43.3.1	The stage is set by the dorsal lip of the blastopore
43.3.2	Body segmentation develops during neurulation
43.3.3	Hox genes control development along the anterior–posterior axis

43.4	What Is the Origin of the Placenta?

43.4.1	Extraembryonic membranes form with contributions from all germ layers
43.4.2	Extraembryonic membranes in mammals form the placenta
43.4.3	The extraembryonic membranes provide means of detecting genetic diseases

» Activity 43.1

43.5	What Are the Stages of Human Development?

43.5.1	The embryo becomes a fetus in the first trimester
43.5.2	The fetus grows and matures during the second and third trimesters
43.5.3	Developmental changes continue throughout life

Chapter Summary

» Flashcards 43.1

» Flashcards 43.2

» Online Quiz 43

» Suggested Readings 43

» Key Terms 43

» Experiment Links 43

» Interactive Summary 43

» Interactive Quiz 43

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

44	Neurons and Nervous Systems

Fear and survival in the brain

44.1	What Cells Are Unique to the Nervous System?

44.1.1	Neuronal networks range in complexity
44.1.2	Neurons are the functional units of nervous systems
44.1.3	Glial cells are also important components of nervous systems

44.2	How Do Neurons Generate and Conduct Signals?

44.2.1	Simple electrical concepts underlie neuronal function
44.2.2	Membrane potentials can be measured with electrodes
44.2.3	Ion pumps and channels generate membrane potentials
44.2.4	Ion channels and their properties can now be studied directly
44.2.5	Gated ion channels alter membrane potential
44.2.6	Sudden changes in Na⁺ and K⁺ channels generate action potentials
44.2.7	Action potentials are conducted along axons without loss of signal
44.2.8	Action potentials can jump along axons

» Animated Tutorial 44.1

» Animated Tutorial 44.2

44.3	How Do Neurons Communicate with Other Cells?

44.3.1	The neuromuscular junction is a model chemical synapse
44.3.2	The arrival of an action potential causes the release of neurotransmitter
44.3.3	The postsynaptic membrane responds to neurotransmitter
44.3.4	Synapses between neurons can be excitatory or inhibitory
44.3.5	The postsynaptic cell sums excitatory and inhibitory input
44.3.6	Synapses can be fast or slow
44.3.7	Electrical synapses are fast but do not integrate information well
44.3.8	The action of a neurotransmitter depends on the receptor to which it binds
44.3.9	Glutamate receptors may be involved in learning and memory
44.3.10	To turn off responses, synapses must be cleared of neurotransmitter

» Animated Tutorial 44.3

» Activity 44.1

Chapter Summary

» Flashcards 44.1

» Flashcards 44.2

» Online Quiz 44

» Suggested Readings 44

» Key Terms 44

» Experiment Links 44

» Interactive Summary 44

» Interactive Quiz 44

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

45	Sensory Systems

Out of range

45.1	How Do Sensory Cells Convert Stimuli into Action Potentials?

45.1.1	Sensory receptor proteins act on ion channels
45.1.2	Sensory transduction involves changes in membrane potentials
45.1.3	Sensation depends on which neurons receive action potentials from sensory cells
45.1.4	Many receptors adapt to repeated stimulation

45.2	How Do Sensory Systems Detect Chemical Stimuli?

45.2.1	Arthropods provide good examples for studying chemoreception
45.2.2	Olfaction is the sense of smell
45.2.3	The vomeronasal organ senses pheromones
45.2.4	Gustation is the sense of taste

45.3	How Do Sensory Systems Detect Mechanical Forces?

45.3.1	Many different cells respond to touch and pressure
45.3.2	Mechanoreceptors are found in muscles, tendons, and ligaments
45.3.3	Auditory systems use hair cells to sense sound waves
45.3.4	Hair cells provide information about displacement

» Animated Tutorial 45.1

» Activity 45.1

45.4	How Do Sensory Systems Detect Light?

45.4.1	Rhodopsins are responsible for photosensitivity
45.4.2	Invertebrates have a variety of visual systems
45.4.3	Image-forming eyes evolved independently in vertebrates and cephalopods
45.4.4	The vertebrate retina receives and processes visual information

» Activity 45.2

» Activity 45.3

Chapter Summary

» Flashcards 45

» Online Quiz 45

» Suggested Readings 45

» Key Terms 45

» Experiment Links 45

» Interactive Summary 45

» Interactive Quiz 45

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

46	The Mammalian Nervous System: Structure and Higher Function

Can our brains be full?

46.1	How Is the Mammalian Nervous System Organized?

46.1.1	A functional organization of the nervous system is based on flow and type of information
46.1.2	The vertebrate CNS develops from the embryonic neural tube
46.1.3	The spinal cord transmits and processes information
46.1.4	The reticular system alerts the forebrain
46.1.5	The core of the forebrain controls physiological drives, instincts, and emotions
46.1.6	Regions of the telencephalon interact to produce consciousness and control behavior

» Animated Tutorial 46.1

» Activity 46.1

46.2	How Is Information Processed by Neuronal Networks?

46.2.1	The autonomic nervous system controls involuntary physiological functions
46.2.2	Patterns of light falling on the retina are integrated by the visual cortex
46.2.3	Cortical cells receive input from both eyes

» Animated Tutorial 46.2

46.3	Can Higher Functions Be Understood in Cellular Terms?

46.3.1	Sleep and dreaming are reflected in electrical patterns in the cerebral cortex
46.3.2	Some learning and memory can be localized to specific brain areas
46.3.3	Language abilities are localized in the left cerebral hemisphere
46.3.4	What is consciousness?

» Activity 46.2

Chapter Summary

» Activity 46.3

» Flashcards 46.1

» Flashcards 46.2

» Online Quiz 46

» Suggested Readings 46

» Key Terms 46

» Experiment Links 46

» Interactive Summary 46

» Interactive Quiz 46

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

47	Effectors: How Animals Get Things Done

Champion jumpers

47.1	How Do Muscles Contract?

47.1.1	Sliding filaments cause skeletal muscle to contract
47.1.2	Actin–myosin interactions cause filaments to slide
47.1.3	Actin–myosin interactions are controlled by calcium ions
47.1.4	Cardiac muscle causes the heart to beat
47.1.5	Smooth muscle causes slow contractions of many internal organs
47.1.6	Single skeletal muscle twitches are summed into graded contractions

» Animated Tutorial 47.1

» Activity 47.1

» Activity 47.2

» Animated Tutorial 47.2

47.2	What Determines Muscle Strength and Endurance?

47.2.1	Muscle fiber types determine endurance and strength
47.2.2	A muscle has an optimal length for generating maximum tension
47.2.3	Exercise increases muscle strength and endurance
47.2.4	Muscle ATP supply limits performance

47.3	What Roles Do Skeletal Systems Play in Movement?

47.3.1	A hydrostatic skeleton consists of fluid in a muscular cavity
47.3.2	Exoskeletons are rigid outer structures
47.3.3	Vertebrate endoskeletons provide supports for muscles
47.3.4	Bones develop from connective tissues
47.3.5	Bones that have a common joint can work as a lever

» Activity 47.3

47.4	What Are Some Other Kinds of Effectors?

47.4.1	Chromatophores allow an animal to change its color or pattern
47.4.2	Glands secrete chemicals for defense, communication, or predation
47.4.3	Electric organs generate electricity used for sensing, communication, defense, or attack
47.4.4	Light-emitting organs use enzymes to produce light

Chapter Summary

» Flashcards 47.1

» Flashcards 47.2

» Online Quiz 47

» Suggested Readings 47

» Key Terms 47

» Experiment Links 47

» Interactive Summary 47

» Interactive Quiz 47

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

48	Gas Exchange in Animals

High fliers

48.1	What Physical Factors Govern Respiratory Gas Exchange?

48.1.1	Diffusion is driven by concentration differences
48.1.2	Fick’s law applies to all systems of gas exchange
48.1.3	Air is a better respiratory medium than water
48.1.4	High temperatures create respiratory problems for aquatic animals
48.1.5	O₂ availability decreases with altitude
48.1.6	CO₂ is lost by diffusion

48.2	What Adaptations Maximize Respiratory Gas Exchange?

48.2.1	Respiratory organs have large surface areas
48.2.2	Transporting gases to and from the exchange surfaces optimizes partial pressure gradients
48.2.3	Insects have airways throughout their bodies
48.2.4	Fish gills use countercurrent flow to maximize gas exchange
48.2.5	Birds use unidirectional ventilation to maximize gas exchange
48.2.6	Tidal ventilation produces dead space that limits gas exchange efficiency

» Animated Tutorial 48.1

48.3	How Do Human Lungs Work?

48.3.1	Respiratory tract secretions aid ventilation
48.3.2	Lungs are ventilated by pressure changes in the thoracic cavity

» Animated Tutorial 48.2

» Activity 48.1

48.4	How Does Blood Transport Respiratory Gases?

48.4.1	Hemoglobin combines reversibly with oxygen
48.4.2	Myoglobin holds an oxygen reserve
48.4.3	The affinity of hemoglobin for oxygen is variable
48.4.4	Carbon dioxide is transported as bicarbonate ions in the blood

» Activity 48.2

48.5	How is Breathing Regulated?

48.5.1	Breathing is controlled in the brain stem
48.5.2	Regulating breathing requires feedback information

Chapter Summary

» Activity 48.3

» Flashcards 48

» Online Quiz 48

» Suggested Readings 48

» Key Terms 48

» Experiment Links 48

» Interactive Summary 48

» Interactive Quiz 48

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

49	Circulatory Systems

You gotta have heart

49.1	Why Do Animals Need a Circulatory System?

49.1.1	Some animals do not have circulatory systems
49.1.2	Open circulatory systems move extracellular fluid
49.1.3	Closed circulatory systems circulate blood through a system of blood vessels

49.2	How Have Vertebrate Circulatory Systems Evolved?

49.2.1	Fish have two-chambered hearts
49.2.2	Amphibians have three-chambered hearts
49.2.3	Reptiles have exquisite control of pulmonary and systemic circulation
49.2.4	Birds and mammals have fully separated pulmonary and systemic circuits

» Activity 49.1

49.3	How Does the Mammalian Heart Function?

49.3.1	Blood flows from right heart to lungs to left heart to body
49.3.2	The heartbeat originates in the cardiac muscle
49.3.3	A conduction system coordinates the contraction of heart muscle
49.3.4	Electrical properties of ventricular muscles sustain heart contraction
49.3.5	The ECG records the electrical activity of the heart

» Activity 49.2

» Animated Tutorial 49.1

49.4	What Are the Properties of Blood and Blood Vessels?

49.4.1	Red blood cells transport respiratory gases
49.4.2	Platelets are essential for blood clotting
49.4.3	Plasma is a complex solution
49.4.4	Blood circulates throughout the body in a system of blood vessels
49.4.5	Materials are exchanged in capillary beds by filtration, osmosis, and diffusion
49.4.6	Blood flows back to the heart through veins
49.4.7	Lymphatic vessels return interstitial fluid to the blood
49.4.8	Vascular disease is a killer

» Activity 49.3

49.5	How Is the Circulatory System Controlled and Regulated?

49.5.1	Autoregulation matches local blood flow to local need
49.5.2	Arterial pressure is controlled and regulated by hormonal and neuronal mechanisms
49.5.3	Cardiovascular control in diving mammals conserves oxygen

Chapter Summary

» Flashcards 49.1

» Flashcards 49.2

» Online Quiz 49

» Suggested Readings 49

» Key Terms 49

» Experiment Links 49

» Interactive Summary 49

» Interactive Quiz 49

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

50	Nutrition, Digestion, and Absorption

An obesity epidemic

50.1	What Do Animals Require from Food?

50.1.1	Energy can be measured in calories
50.1.2	Energy budgets reveal how animals use their resources
50.1.3	Sources of energy can be stored in the body
50.1.4	Food provides carbon skeletons for biosynthesis
50.1.5	Animals need mineral elements for a variety of functions
50.1.6	Animals must obtain vitamins from food
50.1.7	Nutrient deficiencies result in diseases

» Activity 50.1

» Activity 50.2

50.2	How Do Animals Ingest and Digest Food?

50.2.1	The food of herbivores is often low in energy and hard to digest
50.2.2	Carnivores must detect, capture, and kill prey
50.2.3	Vertebrate species have distinctive teeth
50.2.4	Animals digest their food extracellularly
50.2.5	Tubular guts have an opening at each end
50.2.6	Digestive enzymes break down complex food molecules

» Activity 50.3

50.3	How Does the Vertebrate Gastrointestinal System Function?

50.3.1	The vertebrate gut consists of concentric tissue layers
50.3.2	Mechanical activity moves food through the gut and aids digestion
50.3.3	Chemical digestion begins in the mouth and the stomach
50.3.4	What causes stomach ulcers?
50.3.5	The stomach gradually releases its contents to the small intestine
50.3.6	Most chemical digestion occurs in the small intestine
50.3.7	Nutrients are absorbed in the small intestine
50.3.8	Absorbed nutrients go to the liver
50.3.9	Water and ions are absorbed in the large intestine
50.3.10	The problem with cellulose

» Activity 50.4

» Animated Tutorial 50.1

50.4	How Is the Flow of Nutrients Controlled and Regulated?

50.4.1	Hormones control many digestive functions
50.4.2	The liver directs the traffic of the molecules that fuel metabolism
50.4.3	Regulating food intake is important

» Animated Tutorial 50.2

50.5	How Do Animals Deal with Ingested Toxins?

50.5.1	The body cannot metabolize many synthetic toxins
50.5.2	Some toxins are retained and concentrated

Chapter Summary

» Flashcards 50.1

» Flashcards 50.2

» Online Quiz 50

» Suggested Readings 50

» Key Terms 50

» Experiment Links 50

» Interactive Summary 50

» Interactive Quiz 50

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

51	Salt And Water Balance And Nitrogen Excretion

Blood, sweat, and tears

51.1	What Roles Do Excretory Organs Play in Maintaining Homeostasis?

51.1.1	Water enters or leaves cells by osmosis
51.1.2	Excretory organs control extracellular fluid osmolarity by filtration, secretion, and reabsorption
51.1.3	Animals can be osmoconformers or osmoregulators
51.1.4	Animals can be ionic conformers or ionic regulators

51.2	How Do Animals Excrete Toxic Wastes from Nitrogen Metabolism?

51.2.1	Animals excrete nitrogen in a number of forms
51.2.2	Most species produce more than one nitrogenous waste

51.3	How Do Invertebrate Excretory Systems Work?

51.3.1	The protonephridia of flatworms excrete water and conserve salts
51.3.2	The metanephridia of annelids process coelomic fluid
51.3.3	The Malpighian tubules of insects depend on active transport

» Activity 51.1

51.4	How Do Vertebrates Maintain Salt and Water Balance?

51.4.1	Marine fishes must conserve water
51.4.2	Terrestrial amphibians and reptiles must avoid desiccation
51.4.3	Birds and mammals can produce highly concentrated urine
51.4.4	The nephron is the functional unit of the vertebrate kidney
51.4.5	Blood is filtered in the glomerulus
51.4.6	The renal tubules convert glomerular filtrate to urine

» Activity 51.2

51.5	How Does the Mammalian Kidney Produce Concentrated Urine?

51.5.1	Kidneys produce urine and the bladder stores it
51.5.2	Nephrons have a regular arrangement in the kidney
51.5.3	Most of the glomerular filtrate is reabsorbed by the proximal convoluted tubule
51.5.4	The loop of Henle creates a concentration gradient in the surrounding tissue
51.5.5	Water permeability of kidney tubules depends on water channels
51.5.6	Water reabsorption begins in the distal convoluted tubule
51.5.7	Urine is concentrated in the collecting duct
51.5.8	The kidneys help regulate acid–base balance
51.5.9	Kidney failure is treated with dialysis

» Animated Tutorial 51.1

» Activity 51.3

51.6	What Mechanisms Regulate Kidney Function?

51.6.1	The kidneys maintain the glomerular filtration rate
51.6.2	Blood osmolarity and blood pressure are regulated by ADH
51.6.3	The heart produces a hormone that influences kidney function

Chapter Summary

» Activity 51.4

» Flashcards 51

» Online Quiz 51

» Suggested Readings 51

» Key Terms 51

» Experiment Links 51

» Interactive Summary 51

» Interactive Quiz 51

» Resource Table of Contents

» Notes

Self-Quiz

For Discussion

For Investigation

52	Ecology and the Distribution of Life

Shelter from the storm

52.1	What Is Ecology?

52.2	How Are Climates Distributed on Earth?

52.2.1	Solar energy drives global climates
52.2.2	Global oceanic circulation is driven by wind patterns
52.2.3	Organisms must adapt to changes in their environment