Question 1

Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?

Accepted Answer

A) tyrosines 
B) glycine and histidine 
C) serine and threonine 
D) glycine and glutamic acid 
E) Any of the 20 amino acids are equally phosphorylated. 
A) tyrosines 
B) glycine and histidine 
C) serine and threonine 
D) glycine and glutamic acid 
E) Any of the 20 amino acids are equally phosphorylated.

Question 2

A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following?

Accepted Answer

A) lower cytoplasmic levels of cAMP 
B) an increase in receptor tyrosine kinase activity 
C) a decrease in transcriptional activity of certain genes 
D) an increase in cytosolic calcium concentration 
E) a decrease in G protein activity 
A) lower cytoplasmic levels of cAMP 
B) an increase in receptor tyrosine kinase activity 
C) a decrease in transcriptional activity of certain genes 
D) an increase in cytosolic calcium concentration 
E) a decrease in G protein activity

Question 3

Use this information to respond to the following questions.
Humans have receptors for two kinds of beta adrenergic compounds such as catecholamines to control cardiac muscle contractions. Some are beta 1 receptors that promote increased heart rate. Other drugs, called beta blockers, slow heart rate. Smooth muscle cells, however, have beta 2 receptors, which mediate muscle relaxation. Blockers of these effects are sometimes used to treat asthma.
-The description above illustrates which of the following?

Accepted Answer

A) The fact that a drug acts on one type of receptor does not mean that it will act on another type. 
B) Beta blockers can be used effectively on any type of muscle. 
C) Beta adrenergic receptors must be in the cytosol if they are going to influence contraction and relaxation. 
D) The chemical structures of the beta 1 and beta 2 receptors must have the same active sites. 
A) The fact that a drug acts on one type of receptor does not mean that it will act on another type. 
B) Beta blockers can be used effectively on any type of muscle. 
C) Beta adrenergic receptors must be in the cytosol if they are going to influence contraction and relaxation. 
D) The chemical structures of the beta 1 and beta 2 receptors must have the same active sites.

Question 4

In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following would provide evidence that this is related to cell signaling?

Accepted Answer

A) Growth factor ligands do not bind as efficiently to receptors. 
B) Their lower hormone concentrations elicit a lesser response. 
C) cAMP levels change very frequently. 
D) Enzymatic activity declines. 
E) ATP production decreases. 
A) Growth factor ligands do not bind as efficiently to receptors. 
B) Their lower hormone concentrations elicit a lesser response. 
C) cAMP levels change very frequently. 
D) Enzymatic activity declines. 
E) ATP production decreases.

Question 5

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

Accepted Answer

A) receptor 
B) relay molecule 
C) transducer 
D) signal molecule 
E) endocrine molecule 
A) receptor 
B) relay molecule 
C) transducer 
D) signal molecule 
E) endocrine molecule

Question 6

The toxin of Vibrio cholerae causes profuse diarrhea because it

Accepted Answer

A) modifies a G protein involved in regulating salt and water secretion. 
B) decreases the cytosolic concentration of calcium ions, making the cells hypotonic. 
C) binds with adenylyl cyclase and triggers the formation of cAMP. 
D) signals IP₃ to act as a second messenger for the release of calcium. 
E) modifies calmodulin and activates a cascade of protein kinases. 
A) modifies a G protein involved in regulating salt and water secretion. 
B) decreases the cytosolic concentration of calcium ions, making the cells hypotonic. 
C) binds with adenylyl cyclase and triggers the formation of cAMP. 
D) signals IP₃ to act as a second messenger for the release of calcium. 
E) modifies calmodulin and activates a cascade of protein kinases.

Question 7

Where do apoptotic signals come from?

Accepted Answer

A) the nucleus only 
B) the ER only 
C) ligand binding only 
D) mitochondrial protein leakage only 
E) all of the above 
A) the nucleus only 
B) the ER only 
C) ligand binding only 
D) mitochondrial protein leakage only 
E) all of the above

Question 8

The human population's life expectancy has increased significantly but seems to have an upper limit. Which of the following might be described as an ecological consequence of passing that upper limit by regulating cell death?

Accepted Answer

A) an increase in the relative frequency of deaths from cancer 
B) an increased need for gerontologists and other professionals to care for the elderly 
C) an increase in the total population of humans on the planet 
D) a decrease in the ratio of younger to older members of the population 
E) a decrease in the birth rate 
A) an increase in the relative frequency of deaths from cancer 
B) an increased need for gerontologists and other professionals to care for the elderly 
C) an increase in the total population of humans on the planet 
D) a decrease in the ratio of younger to older members of the population 
E) a decrease in the birth rate

Question 9

An inhibitor of phosphodiesterase activity would have which of the following effects?

Accepted Answer

A) block the response of epinephrine 
B) decrease the amount of cAMP in the cytoplasm 
C) block the activation of G proteins in response to epinephrine binding to its receptor 
D) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm 
E) block the activation of protein kinase A 
A) block the response of epinephrine 
B) decrease the amount of cAMP in the cytoplasm 
C) block the activation of G proteins in response to epinephrine binding to its receptor 
D) prolong the effect of epinephrine by maintaining elevated cAMP levels in the cytoplasm 
E) block the activation of protein kinase A

Question 10

Sutherland's research showed that cell-to-cell communication can be divided into three distinct parts that follow a particular sequence. In order from first to last, these are

Accepted Answer

A) transduction, response, reception. 
B) reception, transduction, response. 
C) transcription, translation, response. 
D) transduction, transcription, translation. 
E) first messenger, second messenger, product. 
A) transduction, response, reception. 
B) reception, transduction, response. 
C) transcription, translation, response. 
D) transduction, transcription, translation. 
E) first messenger, second messenger, product.

Question 11

If an adult person has a faulty version of the human analogue to ced-4 of the nematode, which of the following is most likely to result?

Accepted Answer

A) neurodegeneration 
B) activation of a developmental pathway found in the worm but not in humans 
C) a form of cancer in which there is insufficient apoptosis 
D) webbing of fingers or toes 
E) excess skin exfoliation 
A) neurodegeneration 
B) activation of a developmental pathway found in the worm but not in humans 
C) a form of cancer in which there is insufficient apoptosis 
D) webbing of fingers or toes 
E) excess skin exfoliation

Question 12

Which of the following is the best explanation for the inability of a specific animal cell to reduce the Ca²⁺ concentration in its cytosol compared with the extracellular fluid?

Accepted Answer

A) blockage of the synaptic signal 
B) loss of transcription factors 
C) insufficient ATP levels in the cytoplasm 
D) low oxygen concentration around the cell 
E) low levels of protein kinase in the cell 
A) blockage of the synaptic signal 
B) loss of transcription factors 
C) insufficient ATP levels in the cytoplasm 
D) low oxygen concentration around the cell 
E) low levels of protein kinase in the cell

Question 13

Which of the following describes the events of apoptosis?

Accepted Answer

A) The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. 
B) Its DNA and organelles become fragmented, it dies, and it is phagocytized. 
C) The cell dies and the presence of its fragmented contents stimulates nearby cells to divide. 
D) Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell ?self-digests. 
E) Its nucleus and organelles are lysed, then the cell enlarges and bursts. 
A) The cell dies, it is lysed, its organelles are phagocytized, and its contents are recycled. 
B) Its DNA and organelles become fragmented, it dies, and it is phagocytized. 
C) The cell dies and the presence of its fragmented contents stimulates nearby cells to divide. 
D) Its DNA and organelles are fragmented, the cell shrinks and forms blebs, and the cell ?self-digests. 
E) Its nucleus and organelles are lysed, then the cell enlarges and bursts.

Question 14

The termination phase of cell signalling requires which of the following?

Accepted Answer

A) removal of the receptor 
B) activation of a different set of relay molecules 
C) converting ATP to cAMP 
D) reduction of signal and reversion of receptor to inactive state 
E) apoptosis 
A) removal of the receptor 
B) activation of a different set of relay molecules 
C) converting ATP to cAMP 
D) reduction of signal and reversion of receptor to inactive state 
E) apoptosis

Question 15

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.

Accepted Answer

A) cAMP 
B) G protein 
C) GTP 
D) adenylyl cyclase 
E) G protein-coupled receptor 
A) cAMP 
B) G protein 
C) GTP 
D) adenylyl cyclase 
E) G protein-coupled receptor

Question 16

Since steroid receptors are located intracellularly, which of the following is true?

Accepted Answer

A) The receptor molecules are themselves lipids or glycolipids. 
B) The steroid/receptor complex can cross the nuclear membrane. 
C) The unbound steroid receptors are quickly recycled by lysosomes. 
D) The concentration of steroid receptors must be relatively high in most cells. 
E) The receptor molecules are free to move in and out of most organelles. 
A) The receptor molecules are themselves lipids or glycolipids. 
B) The steroid/receptor complex can cross the nuclear membrane. 
C) The unbound steroid receptors are quickly recycled by lysosomes. 
D) The concentration of steroid receptors must be relatively high in most cells. 
E) The receptor molecules are free to move in and out of most organelles.

Question 17

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 when epinephrine and glycogen phosphorylase were combined. 
E) Epinephrine was known to have different effects on different types of cells. 
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 when epinephrine and glycogen phosphorylase were combined. 
E) Epinephrine was known to have different effects on different types of cells.

Question 18

Coordinated, systematic cell death is known as

Accepted Answer

A) senescence. 
B) cancer. 
C) apoptosis. 
D) trophic cascade. 
E) synaptic signalling. 
A) senescence. 
B) cancer. 
C) apoptosis. 
D) trophic cascade. 
E) synaptic signalling.

Question 19

What are scaffolding proteins?

Accepted Answer

A) ladderlike proteins that allow receptor-ligand complexes to climb through cells from one position to another 
B) microtubular protein arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores 
C) large molecules to which several relay proteins attach to facilitate cascade effects 
D) relay proteins that orient receptors and their ligands in appropriate directions to facilitate their complexing 
E) proteins that can reach into the nucleus of a cell to affect transcription 
A) ladderlike proteins that allow receptor-ligand complexes to climb through cells from one position to another 
B) microtubular protein arrays that allow lipid-soluble hormones to get from the cell membrane to the nuclear pores 
C) large molecules to which several relay proteins attach to facilitate cascade effects 
D) relay proteins that orient receptors and their ligands in appropriate directions to facilitate their complexing 
E) proteins that can reach into the nucleus of a cell to affect transcription

Question 20

In general, a signal transmitted via phosphorylation of a series of proteins

Accepted Answer

A) brings a conformational change to each protein. 
B) requires binding of a hormone to a cytosol receptor. 
C) cannot occur in yeasts because they lack protein phosphatases. 
D) requires phosphorylase activity. 
E) allows target cells to change their shape and therefore their activity. 
A) brings a conformational change to each protein. 
B) requires binding of a hormone to a cytosol receptor. 
C) cannot occur in yeasts because they lack protein phosphatases. 
D) requires phosphorylase activity. 
E) allows target cells to change their shape and therefore their activity.

Exam 11: Cell Communication

Which of the following amino acids are most frequently phosphorylated by protein kinases in the cytoplasm during signal transduction?

A drug designed to inhibit the response of cells to testosterone would almost certainly result in which of the following?

In research on aging (both cellular aging and organismal aging), it has been found that aged cells do not progress through the cell cycle as they had previously. Which of the following would provide evidence that this is related to cell signaling?

When a neuron responds to a particular neurotransmitter by opening gated ion channels, the neurotransmitter is serving as which part of the signal pathway?

The toxin of Vibrio cholerae causes profuse diarrhea because it

Where do apoptotic signals come from?

The human population's life expectancy has increased significantly but seems to have an upper limit. Which of the following might be described as an ecological consequence of passing that upper limit by regulating cell death?

An inhibitor of phosphodiesterase activity would have which of the following effects?

Sutherland's research showed that cell-to-cell communication can be divided into three distinct parts that follow a particular sequence. In order from first to last, these are

If an adult person has a faulty version of the human analogue to ced-4 of the nematode, which of the following is most likely to result?

Which of the following is the best explanation for the inability of a specific animal cell to reduce the Ca²⁺ concentration in its cytosol compared with the extracellular fluid?

Which of the following describes the events of apoptosis?

The termination phase of cell signalling requires which of the following?

Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase → cAMP. Identify the second messenger.

Since steroid receptors are located intracellularly, which of the following is true?

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

Coordinated, systematic cell death is known as

What are scaffolding proteins?

In general, a signal transmitted via phosphorylation of a series of proteins

Introduction: Evolution and Themes of Biology

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

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

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 Signalling

Nervous Systems

Sensory and Motor Mechanisms

Animal Behaviour

An Introduction to Ecology and the Biosphere

Population Ecology

Community Ecology

Ecosystems and Restoration Ecology

Conservation Biology and Global Change

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