Question 1

GTPase activity is involved in the regulation of signal transduction because it

Accepted Answer

A) increases the available concentration of phosphate. 
B) decreases the amount of G protein in the membrane. 
C) hydrolyzes GTP binding to G protein. 
D) converts cGMP to GTP. 
E) phosphorylates protein kinases. 
A) increases the available concentration of phosphate. 
B) decreases the amount of G protein in the membrane. 
C) hydrolyzes GTP binding to G protein. 
D) converts cGMP to GTP. 
E) phosphorylates protein kinases. C

Question 2

Apoptosis protects healthy "neighbours" from a dying cell by preventing

Accepted Answer

A) cell death spreading from one cell to the next via paracrine signals. 
B) lysosomal enzymes exiting the dying cell that would damage surrounding cells. 
C) release of cellular energy that would interfere with the neighbours' energy budget. 
D) bits of membrane from the dying cell merging with neighbours and bringing in foreign receptors. 
E) neighbouring cells activating immunological responses. 
A) cell death spreading from one cell to the next via paracrine signals. 
B) lysosomal enzymes exiting the dying cell that would damage surrounding cells. 
C) release of cellular energy that would interfere with the neighbours' energy budget. 
D) bits of membrane from the dying cell merging with neighbours and bringing in foreign receptors. 
E) neighbouring cells activating immunological responses. B

Question 3

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 C

Question 4

The activation of receptor tyrosine kinases is characterized by

Accepted Answer

A) dimerization and phosphorylation. 
B) dimerization and IP₃ binding. 
C) a phosphorylation cascade. 
D) GTP hydrolysis. 
E) channel protein shape change. 
A) dimerization and phosphorylation. 
B) dimerization and IP₃ binding. 
C) a phosphorylation cascade. 
D) GTP hydrolysis. 
E) channel protein shape change.

Question 5

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 6

Use this information to answer the following questions.
A major group of G protein-coupled receptors contains seven transmembrane α helices.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 face or on the cytosol face of the membrane.The loop on the cytosol side between helices 5 and 6 is usually substantially longer than the others.
-If you wish to design an experiment to block the G protein-coupled receptor interaction,the block would preferentially affect which of the following?

Accepted Answer

A) the exterior (cytoplasmic)end of the receptor 
B) the cytosolic end of the receptor 
C) the phospholipid's transmembrane domain 
D) the amino acid sequence in the binding site for the G protein 
E) the amino acids in the binding site for the transduction molecules 
A) the exterior (cytoplasmic)end of the receptor 
B) the cytosolic end of the receptor 
C) the phospholipid's transmembrane domain 
D) the amino acid sequence in the binding site for the G protein 
E) the amino acids in the binding site for the transduction molecules

Question 7

In C.elegans,ced-9 prevents apoptosis in a normal cell in which of the following ways?

Accepted Answer

A) It prevents the caspase activity of ced-3 and ced-4. 
B) Ced-9 remains inactive until it is signalled by ced-3 and other caspases. 
C) Ced-9 cleaves to produce ced-3 and ced-4. 
D) Ced-9 enters the nucleus and activates apoptotic genes. 
E) Ced-9 prevents blebbing by its action on the cell membrane. 
A) It prevents the caspase activity of ced-3 and ced-4. 
B) Ced-9 remains inactive until it is signalled by ced-3 and other caspases. 
C) Ced-9 cleaves to produce ced-3 and ced-4. 
D) Ced-9 enters the nucleus and activates apoptotic genes. 
E) Ced-9 prevents blebbing by its action on the cell membrane.

Question 8

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 9

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 10

Binding of a signalling 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) phosphorylated receptor tyrosine kinase dimer 
D) ligand-gated ion channel 
E) intracellular receptor 
A) receptor tyrosine kinase 
B) G protein-coupled receptor 
C) phosphorylated receptor tyrosine kinase dimer 
D) ligand-gated ion channel 
E) intracellular receptor

Question 11

Which of the following is characterized by molecules from an adjacent cell being released to interact with neighbouring cells by binding with surface receptors and opening ion channels?

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 12

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

Accepted Answer

A) The animal has as many genes as complex organisms, but 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 as many genes as complex organisms, but 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 13

Which of the following is characteristic of aldosterone action?

Accepted Answer

A) protein phosphorylation 
B) cell-surface receptor binding 
C) internal receptor binding 
D) second messenger activation 
E) ion flow across the plasma membrane 
A) protein phosphorylation 
B) cell-surface receptor binding 
C) internal receptor binding 
D) second messenger activation 
E) ion flow across the plasma membrane

Question 14

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 15

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?

Accepted Answer

A) tyrosine kinases 
B) serine/threonine kinases 
C) phosphodiesterase 
D) phospholipase C 
E) adenylyl cyclase 
A) tyrosine kinases 
B) serine/threonine kinases 
C) phosphodiesterase 
D) phospholipase C 
E) adenylyl cyclase

Question 16

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 17

Which of the following most likely would be an immediate result of growth factor binding to its receptor?

Accepted Answer

A) protein kinase activity 
B) adenylyl cyclase activity 
C) GTPase activity 
D) protein phosphatase activity 
E) phosphorylase activity 
A) protein kinase activity 
B) adenylyl cyclase activity 
C) GTPase activity 
D) protein phosphatase activity 
E) phosphorylase activity

Question 18

Use the following figure to answer the questions below.
  
-In the above diagram,what is the significance of E?

Accepted Answer

A) It allows the proteins to move away from the initial response site. 
B) It allows for amplification of the initial signal. 
C) It allows cross-talk with DNA. 
D) it provides an alternative pathway for ATP production. 
E) It is the protein scaffold that allows enzymes to move. 
A) It allows the proteins to move away from the initial response site. 
B) It allows for amplification of the initial signal. 
C) It allows cross-talk with DNA. 
D) it provides an alternative pathway for ATP production. 
E) It is the protein scaffold that allows enzymes to move.

Question 19

Apoptosis involves all but which of the following?

Accepted Answer

A) fragmentation of the DNA 
B) cell-signalling pathways 
C) activation of cellular enzymes 
D) lysis of the cell 
E) digestion of cellular contents by scavenger cells 
A) fragmentation of the DNA 
B) cell-signalling pathways 
C) activation of cellular enzymes 
D) lysis of the cell 
E) digestion of cellular contents by scavenger cells

Question 20

When yeast cells release mating factors,what happens?

Accepted Answer

A) The mating factors induce changes in the cells that lead to cell fusion. 
B) The affected cells produce more of the a factor as a positive feedback. 
C) One cell nucleus binds the mating factors and produces a new nucleus in the opposite cell. 
D) The mating factors stimulate cell membrane disintegration, releasing the mating factors and leading to new yeast cells. 
E) The cells in turn release a growth factor that stimulates mitosis in both cells. 
A) The mating factors induce changes in the cells that lead to cell fusion. 
B) The affected cells produce more of the a factor as a positive feedback. 
C) One cell nucleus binds the mating factors and produces a new nucleus in the opposite cell. 
D) The mating factors stimulate cell membrane disintegration, releasing the mating factors and leading to new yeast cells. 
E) The cells in turn release a growth factor that stimulates mitosis in both cells.

Exam 11: Cell Communication

GTPase activity is involved in the regulation of signal transduction because it

Apoptosis protects healthy "neighbours" from a dying cell by preventing

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?

The activation of receptor tyrosine kinases is characterized by

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

In C.elegans,ced-9 prevents apoptosis in a normal cell in which of the following ways?

Coordinated,systematic cell death is known as

Where do apoptotic signals come from?

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

Which of the following is characterized by molecules from an adjacent cell being released to interact with neighbouring cells by binding with surface receptors and opening ion channels?

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

Which of the following is characteristic of aldosterone action?

What are scaffolding proteins?

An inhibitor of which of the following could be used to block the release of calcium from the endoplasmic reticulum?

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

Which of the following most likely would be an immediate result of growth factor binding to its receptor?

Use the following figure to answer the questions below. -In the above diagram,what is the significance of E?

Apoptosis involves all but which of the following?

When yeast cells release mating factors,what happens?

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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