Question 1

Which of the following is true for the signalling 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) It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
E) It would employ a transduction pathway directly from an external messenger. 
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) It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma membrane. 
E) It would employ a transduction pathway directly from an external messenger.

Question 2

Which of the following statements is true of signal molecules?

Accepted Answer

A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. 
B) In response to some G protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP₃ and calcium. 
C) In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus. 
D) Toxins such as those that cause botulism and cholera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule. 
E) Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors. 
A) When signal molecules first bind to receptor tyrosine kinases, the receptors phosphorylate a number of nearby molecules. 
B) In response to some G protein-mediated signals, a special type of lipid molecule associated with the plasma membrane is cleaved to form IP₃ and calcium. 
C) In most cases, signal molecules interact with the cell at the plasma membrane and then enter the cell and eventually the nucleus. 
D) Toxins such as those that cause botulism and cholera interfere with the ability of activated G proteins to hydrolyze GTP to GDP, resulting in phosphodiesterase activity in the absence of an appropriate signal molecule. 
E) Protein kinase A activation is one possible result of signal molecules binding to G protein-coupled receptors.

Question 3

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 4

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.

Question 5

Use the following figure to answer the questions below.
  
-The structure labelled A is

Accepted Answer

A) very small. 
B) hydrophilic. 
C) hydrophobic. 
D) NO. 
E) a hormone. 
A) very small. 
B) hydrophilic. 
C) hydrophobic. 
D) NO. 
E) a hormone.

Question 6

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 7

The best description of the function of phosphatases in signal transduction is that it

Accepted Answer

A) moves the phosphate group of the transduction pathway to the next molecule of a series. 
B) prevents a protein kinase from being reused when there is another extracellular signal. 
C) amplifies the transduction signal so it affects multiple transducers. 
D) amplifies the second messengers such as cAMP. 
E) inactivates protein kinases and turns off the signal transduction. 
A) moves the phosphate group of the transduction pathway to the next molecule of a series. 
B) prevents a protein kinase from being reused when there is another extracellular signal. 
C) amplifies the transduction signal so it affects multiple transducers. 
D) amplifies the second messengers such as cAMP. 
E) inactivates protein kinases and turns off the signal transduction.

Question 8

Which of the following is the original signal inhibited by Viagra?

Accepted Answer

A) hydrolysis of cGMP to GMP. 
B) hydrolysis of GTP to GDP. 
C) phosphorylation of GDP. 
D) dephosphorylation cGMP. 
E) removal of GMP from the cell. 
A) hydrolysis of cGMP to GMP. 
B) hydrolysis of GTP to GDP. 
C) phosphorylation of GDP. 
D) dephosphorylation cGMP. 
E) removal of GMP from the cell.

Question 9

Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins?

Accepted Answer

A) G protein-coupled receptor signalling 
B) ligand-gated ion channel signalling 
C) adenylyl cyclase activity 
D) phosphatase activity 
E) receptor tyrosine kinase activity 
A) G protein-coupled receptor signalling 
B) ligand-gated ion channel signalling 
C) adenylyl cyclase activity 
D) phosphatase activity 
E) receptor tyrosine kinase activity

Question 10

Use this information to answer the following questions.
Affinity chromatography is a method that can be used to purify cell-surface receptors,while they retain their hormone-binding ability.A ligand (hormone)for a receptor of interest is chemically linked to polystyrene beads.A solubilized preparation of membrane proteins is passed over a column containing these beads.Only the receptor binds to the beads.
-What might be one approach to design a drug to maintain low blood sugar levels?

Accepted Answer

A) activate epinephrine receptors 
B) increase cAMP production in liver cells 
C) block G protein activity in liver cells 
D) increase phosphorylase activity 
E) increase membrane fluidity 
A) activate epinephrine receptors 
B) increase cAMP production in liver cells 
C) block G protein activity in liver cells 
D) increase phosphorylase activity 
E) increase membrane fluidity

Question 11

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 12

Use the following figure to answer the questions below.
  
-In the above diagram,the structure labelled A is a(n)

Accepted Answer

A) second messenger. 
B) activated relay molecule. 
C) ligand. 
D) receptor. 
E) phosphorylation cascade. 
A) second messenger. 
B) activated relay molecule. 
C) ligand. 
D) receptor. 
E) phosphorylation cascade.

Question 13

Which type of receptor in the plasma membrane reacts by forming dimers,adding phosphate groups,and then activating relay proteins?

Accepted Answer

A) G protein-coupled receptors 
B) ligand-gated ion channels 
C) steroid receptors 
D) quorum sensing receptors 
A) G protein-coupled receptors 
B) ligand-gated ion channels 
C) steroid receptors 
D) quorum sensing receptors

Question 14

What must a target organ do to respond to a particular hormone?

Accepted Answer

A) modify its plasma membrane to assist transport of the hormone entering the cytoplasm 
B) be from the same cell type as the organ that produced the hormone 
C) experience an imbalance that disrupts its normal function 
D) have receptors that recognize and bind the hormone molecule 
E) break down the hormone 
A) modify its plasma membrane to assist transport of the hormone entering the cytoplasm 
B) be from the same cell type as the organ that produced the hormone 
C) experience an imbalance that disrupts its normal function 
D) have receptors that recognize and bind the hormone molecule 
E) break down the hormone

Question 15

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 16

Which of the following is characterized by a cell releasing a signal molecule into the environment,followed by a number of cells in the immediate vicinity responding?

Accepted Answer

A) hormonal signalling 
B) autocrine signalling 
C) paracrine signalling 
D) endocrine signalling 
E) synaptic signalling 
A) hormonal signalling 
B) autocrine signalling 
C) paracrine signalling 
D) endocrine signalling 
E) synaptic signalling

Question 17

Epinephrine signals which of the following?

Accepted Answer

A) a decrease in levels of cAMP as a result of bypassing the plasma membrane 
B) lower blood glucose by binding to liver cells 
C) interactions with insulin inside muscle cells 
D) interactions directly with glycogen phosphorylase 
E) elevation of cytosolic concentrations of cyclic AMP 
A) a decrease in levels of cAMP as a result of bypassing the plasma membrane 
B) lower blood glucose by binding to liver cells 
C) interactions with insulin inside muscle cells 
D) interactions directly with glycogen phosphorylase 
E) elevation of cytosolic concentrations of cyclic AMP

Question 18

A drug designed to inhibit the response of cells to a growth factor 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 19

Which of the following statements correctly describes quorum sensing?

Accepted Answer

A) cell-cell communication 
B) allows cells to act asynchonously 
C) recent evolutionary feature 
D) allows organisms to undergo apoptosis 
E) always involves cells of the opposite sex. 
A) cell-cell communication 
B) allows cells to act asynchonously 
C) recent evolutionary feature 
D) allows organisms to undergo apoptosis 
E) always involves cells of the opposite sex.

Question 20

In the formation of biofilms,such as those forming on unbrushed teeth,cell signalling serves which function?

Accepted Answer

A) formation of mating complexes 
B) secretion of apoptotic signals 
C) aggregation of bacteria 
D) secretion of substances that inhibit foreign bacteria 
E) digestion of unwanted parasite populations 
A) formation of mating complexes 
B) secretion of apoptotic signals 
C) aggregation of bacteria 
D) secretion of substances that inhibit foreign bacteria 
E) digestion of unwanted parasite populations

Exam 11: Cell Communication

Which of the following is true for the signalling system in an animal cell that lacks the ability to produce GTP?

Which of the following statements is true of signal molecules?

The toxin of Vibrio cholerae causes profuse diarrhea because it

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

Use the following figure to answer the questions below. -The structure labelled A is

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

The best description of the function of phosphatases in signal transduction is that it

Which of the following is the original signal inhibited by Viagra?

Which of the following would be inhibited by a drug that specifically blocks the addition of phosphate groups to proteins?

Which of the following is a correct association?

Use the following figure to answer the questions below. -In the above diagram,the structure labelled A is a(n)

Which type of receptor in the plasma membrane reacts by forming dimers,adding phosphate groups,and then activating relay proteins?

What must a target organ do to respond to a particular hormone?

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

Which of the following is characterized by a cell releasing a signal molecule into the environment,followed by a number of cells in the immediate vicinity responding?

Epinephrine signals which of the following?

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

Which of the following statements correctly describes quorum sensing?

In the formation of biofilms,such as those forming on unbrushed teeth,cell signalling serves which function?

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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