Question 1

G proteins and G-protein-linked receptors

Accepted Answer

A) are found only in animal cells, and only embedded in or located just beneath the cell's membrane. 
B) are found only in bacterial cells, embedded in the cell's plasma membrane only. 
C) are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms. 
D) probably evolved from an adaptation of the citric acid cycle. 
E) are not widespread in nature and were unimportant in the evolution of eukaryotes. 
A) are found only in animal cells, and only embedded in or located just beneath the cell's membrane. 
B) are found only in bacterial cells, embedded in the cell's plasma membrane only. 
C) are thought to have evolved very early, because of their similar structure and function in a wide variety of modern organisms. 
D) probably evolved from an adaptation of the citric acid cycle. 
E) are not widespread in nature and were unimportant in the evolution of eukaryotes.

Question 2

Protein phosphorylation is commonly involved with all of the following except

Accepted Answer

A) regulation of transcription by extracellular signal molecules. 
B) enzyme activation. 
C) activation of G protein-coupled receptors. 
D) activation of receptor tyrosine kinases. 
E) activation of protein kinase molecules. 
A) regulation of transcription by extracellular signal molecules. 
B) enzyme activation. 
C) activation of G protein-coupled receptors. 
D) activation of receptor tyrosine kinases. 
E) activation of protein kinase molecules.

Question 3

The receptors for a group of signaling molecules known as growth factors are often

Accepted Answer

A) ligand-gated ion channels. 
B) G-protein-linked receptors. 
C) cyclic AMP. 
D) receptor tyrosine kinases. 
E) neurotransmitters. 
A) ligand-gated ion channels. 
B) G-protein-linked receptors. 
C) cyclic AMP. 
D) receptor tyrosine kinases. 
E) neurotransmitters.

Question 4

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to

Accepted Answer

A) the active site of an allosteric enzyme in the cytoplasm that binds to a specific substrate. 
B) RNA specifying the amino acids in a polypeptide. 
C) a particular metabolic pathway operating within a specific organelle. 
D) an enzyme with an optimum pH and temperature for activity. 
E) genes making up a chromosome. 
A) the active site of an allosteric enzyme in the cytoplasm that binds to a specific substrate. 
B) RNA specifying the amino acids in a polypeptide. 
C) a particular metabolic pathway operating within a specific organelle. 
D) an enzyme with an optimum pH and temperature for activity. 
E) genes making up a chromosome.

Question 5

The use of beta 2 antagonist drugs may be useful in asthma because

Accepted Answer

A) they may increase constriction of the skeletal muscle of the chest wall. 
B) they may increase heart rate and therefore allow the patient to get more oxygen circulated. 
C) they may dilate the bronchioles by relaxing their smooth muscle. 
D) they may override the beta blockers that the patient is already taking. 
E) they may obstruct all G protein-mediated receptors. 
A) they may increase constriction of the skeletal muscle of the chest wall. 
B) they may increase heart rate and therefore allow the patient to get more oxygen circulated. 
C) they may dilate the bronchioles by relaxing their smooth muscle. 
D) they may override the beta blockers that the patient is already taking. 
E) they may obstruct all G protein-mediated receptors.

Question 6

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) phosphorylase activity and the catabolism of glucose 
E) 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) phosphorylase activity and the catabolism of glucose 
E) adenylyl cyclase activity and the conversion of cAMP to AMP

Question 7

Up to 60% of all medicines used today exert their effects by influencing what structures in the cell membrane?

Accepted Answer

A) tyrosine-kinases receptors 
B) ligand-gated ion channel receptors 
C) growth factors 
D) G proteins 
E) cholesterol 
A) tyrosine-kinases receptors 
B) ligand-gated ion channel receptors 
C) growth factors 
D) G proteins 
E) cholesterol

Question 8

Membrane receptors that attach phosphates to specific animo acids in proteins are

Accepted Answer

A) not found in humans. 
B) called receptor tyrosine-kinases. 
C) a class of GTP G-protein signal receptors. 
D) associated with several bacterial diseases in humans. 
E) important in yeast mating factors that contain amino acids. 
A) not found in humans. 
B) called receptor tyrosine-kinases. 
C) a class of GTP G-protein signal receptors. 
D) associated with several bacterial diseases in humans. 
E) important in yeast mating factors that contain amino acids.

Question 9

A small molecule that specifically binds to another molecule, usually a larger one

Accepted Answer

A) is called a signal transducer. 
B) is called a ligand. 
C) is called a polymer. 
D) seldom is involved in hormonal signaling. 
E) usually terminates a signal reception. 
A) is called a signal transducer. 
B) is called a ligand. 
C) is called a polymer. 
D) seldom is involved in hormonal signaling. 
E) usually terminates a signal reception.

Question 10

What would be True for the signaling system in an animal cell that lacks the ability to produce GTP?

Accepted Answer

A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
B) It could activate only the epinephrine system. 
C) It would be able to carry out reception and transduction, but would not be able to respond to a signal. 
D) Only A and C are True. 
E) A, B, and C are True. 
A) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
B) It could activate only the epinephrine system. 
C) It would be able to carry out reception and transduction, but would not be able to respond to a signal. 
D) Only A and C are True. 
E) A, B, and C are True.

Question 11

The main proteases involved in apoptosis are

Accepted Answer

A) ced-3 and ced-4. 
B) inactive. 
C) cytochromes. 
D) caspases. 
E) G proteins. 
A) ced-3 and ced-4. 
B) inactive. 
C) cytochromes. 
D) caspases. 
E) G proteins.

Question 12

Which is True of transcription factors?

Accepted Answer

A) They regulate the synthesis of DNA in response to a signal. 
B) Some transcribe ATP into cAMP. 
C) They initiate the epinephrine response in animal cells. 
D) They control which genes are expressed. 
E) They are needed to regulate the synthesis of lipids in the cytoplasm. 
A) They regulate the synthesis of DNA in response to a signal. 
B) Some transcribe ATP into cAMP. 
C) They initiate the epinephrine response in animal cells. 
D) They control which genes are expressed. 
E) They are needed to regulate the synthesis of lipids in the cytoplasm.

Question 13

Testosterone functions inside a cell by

Accepted Answer

A) acting as a signal receptor that activates ion-channel proteins. 
B) binding with a receptor protein that enters the nucleus and activates specific genes. 
C) acting as a steroid signal receptor that activates ion-channel proteins. 
D) becoming a second messenger that inhibits adenylyl cyclase. 
E) coordinating a phosphorylation cascade that increases glycogen metabolism. 
A) acting as a signal receptor that activates ion-channel proteins. 
B) binding with a receptor protein that enters the nucleus and activates specific genes. 
C) acting as a steroid signal receptor that activates ion-channel proteins. 
D) becoming a second messenger that inhibits adenylyl cyclase. 
E) coordinating a phosphorylation cascade that increases glycogen metabolism.

Question 14

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 to the intestinal cells. 
C) binds with adenylyl cyclase and triggers the formation of cAMP. 
D) signals inositol trisphosphate to become 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 to the intestinal cells. 
C) binds with adenylyl cyclase and triggers the formation of cAMP. 
D) signals inositol trisphosphate to become a second messenger for the release of calcium. 
E) modifies calmodulin and activates a cascade of protein kinases.

Question 15

Adenylyl cyclase has the opposite effect of which of the following?

Accepted Answer

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

Question 16

What could happen to the target cells in an animal that lack receptors for local regulators?

Accepted Answer

A) They could compensate by receiving nutrients via an a factor. 
B) They could develop normally in response to neurotransmitters instead. 
C) They could divide but never reach full size. 
D) They would not be able to multiply in response to growth factors from nearby cells. 
E) Hormones would not be able to interact with target cells. 
A) They could compensate by receiving nutrients via an a factor. 
B) They could develop normally in response to neurotransmitters instead. 
C) They could divide but never reach full size. 
D) They would not be able to multiply in response to growth factors from nearby cells. 
E) Hormones would not be able to interact with target cells.

Question 17

Which of the following is the best explanation for the inability of an 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 18

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to

Accepted Answer

A) design a compound that blocks epinephrine receptor activation. 
B) design a compound that inhibits cAMP production in liver cells. 
C) design a compound to block G-protein activity in liver cells. 
D) design a compound that inhibits phosphorylase activity. 
E) All of the above are possible approaches. 
A) design a compound that blocks epinephrine receptor activation. 
B) design a compound that inhibits cAMP production in liver cells. 
C) design a compound to block G-protein activity in liver cells. 
D) design a compound that inhibits phosphorylase activity. 
E) All of the above are possible approaches.

Question 19

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

Accepted Answer

A) The animal has very few genes, so that finding those responsible is easier than in a more complex organism. 
B) The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. 
C) This plant has a long-studied aging mechanism that has made understanding its death just a last stage. 
D) While the organism ages, its cells die progressively until the whole organism is dead. 
E) All of its genes are constantly being expressed so all of its proteins are available from each cell. 
A) The animal has very few genes, so that finding those responsible is easier than in a more complex organism. 
B) The nematode undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development. 
C) This plant has a long-studied aging mechanism that has made understanding its death just a last stage. 
D) While the organism ages, its cells die progressively until the whole organism is dead. 
E) All of its genes are constantly being expressed so all of its proteins are available from each cell.

Question 20

Which of the following is (are)True of ligand-gated ion channels?

Accepted Answer

A) They are important in the nervous system. 
B) They lead to changes in sodium and calcium concentrations in cells. 
C) They open or close in response to a chemical signal. 
D) Only A and B are True. 
E) A, B, and C are True. 
A) They are important in the nervous system. 
B) They lead to changes in sodium and calcium concentrations in cells. 
C) They open or close in response to a chemical signal. 
D) Only A and B are True. 
E) A, B, and C are True.

Exam 11: Cell Communication

G proteins and G-protein-linked receptors

Protein phosphorylation is commonly involved with all of the following except

The receptors for a group of signaling molecules known as growth factors are often

Of the following, a receptor protein in a membrane that recognizes a chemical signal is most similar to

The use of beta 2 antagonist drugs may be useful in asthma because

Which of the following is a correct association?

Up to 60% of all medicines used today exert their effects by influencing what structures in the cell membrane?

Membrane receptors that attach phosphates to specific animo acids in proteins are

A small molecule that specifically binds to another molecule, usually a larger one

What would be True for the signaling system in an animal cell that lacks the ability to produce GTP?

The main proteases involved in apoptosis are

Which is True of transcription factors?

Testosterone functions inside a cell by

The toxin of Vibrio cholerae causes profuse diarrhea because it

Adenylyl cyclase has the opposite effect of which of the following?

What could happen to the target cells in an animal that lack receptors for local regulators?

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

If a pharmaceutical company wished to design a drug to maintain low blood sugar levels, one approach might be to

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

Which of the following is (are)True of ligand-gated ion channels?

Introduction: Themes in the Study of Life

The Chemical Context of Life

Water and the Fitness of the Environment

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: Harvesting Chemical Energy

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

Control of Gene Expression

Viruses

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 Introduction to Animal Diversity

Invertebrates

Vertebrates

Plant Structure, Growth, and Development

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

Conservation Biology and Restoration Ecology

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