Question 1

Apoptosis involves all but which of the following?

Accepted Answer

A)  fragmentation of the DNA 
B)  cell-signaling pathways 
C)  lysis of the cell 
D)  digestion of cellular contents by scavenger cells 
A)  fragmentation of the DNA 
B)  cell-signaling pathways 
C)  lysis of the cell 
D)  digestion of cellular contents by scavenger cells

Question 2

In yeast signal transduction, a yeast cell releases a mating factor, which ________.

Accepted Answer

A)  acts back on the same cell that secreted the mating factor, changing its development 
B)  passes through the membranes of neighboring cells, binds to DNA, and initiates transcription 
C)  binds to receptors on the membranes of other types of yeast cells 
D)  diffuses through the membranes of distant cells, causing them to produce factors that initiate long-distance migrations 
A)  acts back on the same cell that secreted the mating factor, changing its development 
B)  passes through the membranes of neighboring cells, binds to DNA, and initiates transcription 
C)  binds to receptors on the membranes of other types of yeast cells 
D)  diffuses through the membranes of distant cells, causing them to produce factors that initiate long-distance migrations

Question 3

What does it mean to say that a signal is transduced?

Accepted Answer

A)  The signal enters the cell directly and binds to a receptor inside. 
B)  The physical form of the signal changes as it passes from the cell membrane to the ultimate intracellular target. 
C)  The signal is amplified, such that even one signal molecule evokes a large response. 
D)  The signal triggers a sequence of phosphorylation events inside the cell. 
A)  The signal enters the cell directly and binds to a receptor inside. 
B)  The physical form of the signal changes as it passes from the cell membrane to the ultimate intracellular target. 
C)  The signal is amplified, such that even one signal molecule evokes a large response. 
D)  The signal triggers a sequence of phosphorylation events inside the cell.

Question 4

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of substances on opposite sides of the membrane?

Accepted Answer

A)  intracellular receptor 
B)  G protein-coupled receptor 
C)  phosphorylated receptor tyrosine kinase dimer 
D)  ligand-gated ion channel 
A)  intracellular receptor 
B)  G protein-coupled receptor 
C)  phosphorylated receptor tyrosine kinase dimer 
D)  ligand-gated ion channel

Question 5

Put the steps of the process of signal transduction in the order they occur.
1)A conformational change in the signal-receptor complex activates an enzyme.
2)Protein kinases are activated.
3)A signal molecule binds to a receptor.
4)Target proteins are phosphorylated.
5)Second messenger molecules are released.

Accepted Answer

A)  1, 2, 3, 4, 5 
B)  3, 1, 2, 4, 5 
C)  3, 1, 5, 2, 4 
D)  1, 2, 5, 3, 4 
A)  1, 2, 3, 4, 5 
B)  3, 1, 2, 4, 5 
C)  3, 1, 5, 2, 4 
D)  1, 2, 5, 3, 4

Question 6

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?

Accepted Answer

A)  receptor tyrosine kinase 
B)  G protein-coupled receptor 
C)  ligand-gated ion channel 
D)  steroid receptor 
A)  receptor tyrosine kinase 
B)  G protein-coupled receptor 
C)  ligand-gated ion channel 
D)  steroid receptor

Question 7

How does the toxin of Vibrio cholerae cause profuse diarrhea?

Accepted Answer

A)  It modifies a G protein involved in regulating salt and water secretion. 
B)  It modifies adenylyl cyclase and triggers excess formation of cAMP. 
C)  It signals IP₃ to act as a second messenger for the release of calcium. 
D)  It modifies a ligand-gated ion channel. 
A)  It modifies a G protein involved in regulating salt and water secretion. 
B)  It modifies adenylyl cyclase and triggers excess formation of cAMP. 
C)  It signals IP₃ to act as a second messenger for the release of calcium. 
D)  It modifies a ligand-gated ion channel.

Question 8

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound that does which of the following?

Accepted Answer

A)  activates epinephrine receptors in liver cells 
B)  increases cAMP production in liver cells 
C)  blocks G protein activity in liver cells 
D)  increases glycogen phosphorylase activity in liver cells 
A)  activates epinephrine receptors in liver cells 
B)  increases cAMP production in liver cells 
C)  blocks G protein activity in liver cells 
D)  increases glycogen phosphorylase activity in liver cells

Question 9

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Accepted Answer

A)  Enzymatic activity was proportional to the amount of calcium added to a cell-free extract. 
B)  Receptor studies indicated that epinephrine was a ligand. 
C)  Glycogen breakdown was observed only when epinephrine was administered to intact cells. 
D)  Glycogen breakdown was observed only when epinephrine and glycogen phosphorylase were mixed. 
A)  Enzymatic activity was proportional to the amount of calcium added to a cell-free extract. 
B)  Receptor studies indicated that epinephrine was a ligand. 
C)  Glycogen breakdown was observed only when epinephrine was administered to intact cells. 
D)  Glycogen breakdown was observed only when epinephrine and glycogen phosphorylase were mixed.

Question 10

Which of the following is a correct association?

Accepted Answer

A)  kinase activity and the addition of a tyrosine 
B)  phosphodiesterase activity and the removal of phosphate groups 
C)  GTPase activity and hydrolysis of GTP to GDP 
D)  adenylyl cyclase activity and the conversion of cAMP to AMP 
A)  kinase activity and the addition of a tyrosine 
B)  phosphodiesterase activity and the removal of phosphate groups 
C)  GTPase activity and hydrolysis of GTP to GDP 
D)  adenylyl cyclase activity and the conversion of cAMP to AMP

Question 11

What is the most likely mechanism by which testosterone functions inside a cell?

Accepted Answer

A)  It acts as a signal receptor that activates tyrosine kinases. 
B)  It binds with a receptor protein that enters the nucleus and activates expression of specific genes. 
C)  It acts as a steroid signal receptor that activates ion channel proteins in the plasma membrane. 
D)  It coordinates a phosphorylation cascade that reduces spermatogenesis. 
A)  It acts as a signal receptor that activates tyrosine kinases. 
B)  It binds with a receptor protein that enters the nucleus and activates expression of specific genes. 
C)  It acts as a steroid signal receptor that activates ion channel proteins in the plasma membrane. 
D)  It coordinates a phosphorylation cascade that reduces spermatogenesis.

Question 12

Why has C. elegans proven to be a useful model for understanding apoptosis?

Accepted Answer

A)  C. elegans does not naturally use apoptosis, but can be induced to do so in the laboratory. 
B)  C. elegans undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. 
C)  C. elegans has large cells wherein apoptosis is easily observed without the aid of a microscope. 
D)  As C. elegans ages, its cells die progressively until the whole organism is dead. 
A)  C. elegans does not naturally use apoptosis, but can be induced to do so in the laboratory. 
B)  C. elegans undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. 
C)  C. elegans has large cells wherein apoptosis is easily observed without the aid of a microscope. 
D)  As C. elegans ages, its cells die progressively until the whole organism is dead.

Question 13

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Accepted Answer

A)  Receptor studies indicated that epinephrine was a ligand. 
B)  Glycogen breakdown was observed only when epinephrine was administered to intact cells. 
C)  Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined in a cell-free system. 
D)  Epinephrine was known to have different effects on many types of cells. 
A)  Receptor studies indicated that epinephrine was a ligand. 
B)  Glycogen breakdown was observed only when epinephrine was administered to intact cells. 
C)  Glycogen breakdown was observed when epinephrine and glycogen phosphorylase were combined in a cell-free system. 
D)  Epinephrine was known to have different effects on many types of cells.

Question 14

Which of the following is true during a typical cAMP-mediated signal transduction event?

Accepted Answer

A)  The second messenger is the last part of the system to be activated. 
B)  A hormone activates the second messenger by directly binding to it. 
C)  The second messenger amplifies the hormonal response by attracting more hormones to the cell being affected. 
D)  Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs. 
A)  The second messenger is the last part of the system to be activated. 
B)  A hormone activates the second messenger by directly binding to it. 
C)  The second messenger amplifies the hormonal response by attracting more hormones to the cell being affected. 
D)  Adenylyl cyclase is activated after the hormone binds to the cell and before phosphorylation of proteins occurs.

Question 15

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

Accepted Answer

A)  It would not be able to activate G proteins on the cytoplasmic side of the plasma membrane. 
B)  It would be able to carry out reception and transduction but would not be able to respond to a signal. 
C)  It would use ATP instead of GTP to activate G proteins on the cytoplasmic side of the plasma membrane. 
D)  It would not be able to activate receptor tyrosine kinases. 
A)  It would not be able to activate G proteins on the cytoplasmic side of the plasma membrane. 
B)  It would be able to carry out reception and transduction but would not be able to respond to a signal. 
C)  It would use ATP instead of GTP to activate G proteins on the cytoplasmic side of the plasma membrane. 
D)  It would not be able to activate receptor tyrosine kinases.

Question 16

A mutation that knocks out the GTPase activity of a G protein would have what effect on a cell?

Accepted Answer

A)  The concentration of available GTP would decrease. 
B)  The number of G proteins in the cell would increase. 
C)  The G protein would be inactivated by a G protein-coupled receptor/signal molecule complex. 
D)  The G protein would always be active. 
A)  The concentration of available GTP would decrease. 
B)  The number of G proteins in the cell would increase. 
C)  The G protein would be inactivated by a G protein-coupled receptor/signal molecule complex. 
D)  The G protein would always be active.

Question 17

Use the following figure to answer the question.
 
In the figure, the dots in the space between the two structures represent which of the following?

Accepted Answer

A)  receptor molecules 
B)  signal transducers 
C)  neurotransmitters 
D)  hormones 
A)  receptor molecules 
B)  signal transducers 
C)  neurotransmitters 
D)  hormones

Question 18

Which of the following statements describes the events of apoptosis?

Accepted Answer

A)  The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. 
B)  The cell's DNA and organelles become fragmented, the cell dies, and it is phagocytized. 
C)  The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells. 
D)  The cell's nucleus and organelles are lysed, and then the cell enlarges and bursts. 
A)  The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. 
B)  The cell's DNA and organelles become fragmented, the cell dies, and it is phagocytized. 
C)  The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells. 
D)  The cell's nucleus and organelles are lysed, and then the cell enlarges and bursts.

Question 19

Many G protein-coupled receptors contain seven transmembrane α-helical domains. The amino end of the protein lies at the exterior of the plasma membrane. Loops of amino acids connect the helices either at the exterior surface or on the cytosolic surface of the membrane. The loop on the cytosolic side between helices 5 and 6 is usually substantially longer than the others. Where would a coupled G protein most likely interact with this receptor?

Accepted Answer

A)  at the amino end 
B)  at the carboxyl end 
C)  along the exterior margin 
D)  at the loop between H5 and H6 
A)  at the amino end 
B)  at the carboxyl end 
C)  along the exterior margin 
D)  at the loop between H5 and H6

Question 20

The activity of adenylyl cyclase is essentially the opposite of which of the following enzymes?

Accepted Answer

A)  protein kinase 
B)  protein phosphatase 
C)  phosphodiesterase 
D)  phosphorylase 
A)  protein kinase 
B)  protein phosphatase 
C)  phosphodiesterase 
D)  phosphorylase

Exam 11: Cell Communication

Apoptosis involves all but which of the following?

In yeast signal transduction, a yeast cell releases a mating factor, which ________.

What does it mean to say that a signal is transduced?

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of substances on opposite sides of the membrane?

Binding of a signaling molecule to which type of receptor leads directly to a change in the distribution of ions on opposite sides of the membrane?

How does the toxin of Vibrio cholerae cause profuse diarrhea?

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to design a compound that does which of the following?

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Which of the following is a correct association?

What is the most likely mechanism by which testosterone functions inside a cell?

Why has C. elegans proven to be a useful model for understanding apoptosis?

Which observation suggested to Sutherland the involvement of a second messenger in epinephrine's effect on liver cells?

Which of the following is true during a typical cAMP-mediated signal transduction event?

If an animal cell suddenly lost the ability to produce GTP, what might happen to its signaling system?

A mutation that knocks out the GTPase activity of a G protein would have what effect on a cell?

Use the following figure to answer the question. In the figure, the dots in the space between the two structures represent which of the following?

Which of the following statements describes the events of apoptosis?

The activity of adenylyl cyclase is essentially the opposite of which of the following enzymes?

Evolution, the Themes of Biology, and Scientific Inquiry

The Chemical Context of Life

Water and Life

Carbon and the Molecular Diversity of Life

The Structure and Function of Large Biological Molecules

A Tour of the Cell

Membrane Structure and Function

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Viruses

DNA Tools and Biotechnology

Genomes and Their Evolution

Descent with Modification: A Darwinian View of Life

The Evolution of Populations

The Origin of Species

The History of Life on Earth

Phylogeny and the Tree of Life

Bacteria and Archaea

Protists

Plant Diversity I: How Plants Colonized Land

Plant Diversity II: The Evolution of Seed Plants

Fungi

An Overview of Animal Diversity

An Introduction to Invertebrates

The Origin and Evolution of Vertebrates

Vascular Plant Structure, Growth, and Development

Resource Acquisition and Transport in Vascular Plants

Soil and Plant Nutrition

Angiosperm Reproduction and Biotechnology

Plant Responses to Internal and External Signals

Basic Principles of Animal Form and Function

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Osmoregulation and Excretion

Hormones and the Endocrine System

Animal Reproduction

Animal Development

Neurons, Synapses, and Signaling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behavior

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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