Question 1

Lipid-soluble signalling molecules,such as testosterone,cross the membranes of all cells but affect only target cells because

Accepted Answer

A) only target cells retain the appropriate DNA segments. 
B) intracellular receptors are present only in target cells. 
C) most cells lack the Y chromosome required. 
D) only target cells possess the cytosolic enzymes that transduce the testosterone. 
E) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor. 
A) only target cells retain the appropriate DNA segments. 
B) intracellular receptors are present only in target cells. 
C) most cells lack the Y chromosome required. 
D) only target cells possess the cytosolic enzymes that transduce the testosterone. 
E) only in target cells is testosterone able to initiate the phosphorylation cascade leading to activated transcription factor.

Question 2

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

Accepted Answer

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

Question 3

Which of the following is true of steroid receptors?

Accepted Answer

A) The receptor molecules are themselves lipids or glycolipids. 
B) The receptor may be inside the cell or nucleus of a target cell. 
C) The unbound steroid receptors are quickly recycled by lysosomes. 
D) Steroid receptors are plasma membrane bound. 
E) Steroid receptors are active until steroid binds. 
A) The receptor molecules are themselves lipids or glycolipids. 
B) The receptor may be inside the cell or nucleus of a target cell. 
C) The unbound steroid receptors are quickly recycled by lysosomes. 
D) Steroid receptors are plasma membrane bound. 
E) Steroid receptors are active until steroid binds.

Question 4

In which of the following ways do plant hormones differ from hormones in animals?

Accepted Answer

A) Plant hormones interact primarily with intracellular receptors. 
B) Plant hormones may travel in air or through vascular systems. 
C) Animal hormones are found in much greater concentration. 
D) Plant hormones are synthesized from two or more distinct molecules. 
E) Animal hormones are primarily for mating and embryonic development. 
A) Plant hormones interact primarily with intracellular receptors. 
B) Plant hormones may travel in air or through vascular systems. 
C) Animal hormones are found in much greater concentration. 
D) Plant hormones are synthesized from two or more distinct molecules. 
E) Animal hormones are primarily for mating and embryonic development.

Question 5

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 6

Which of the following dictates the use of Herceptin in breast cancer treatment?

Accepted Answer

A) If Herceptin is found in the breast lymph nodes of the patient. 
B) If HER2, administered by injection, is in sufficient concentration. 
C) If the patient's cancer cells have excessive levels of HER2. 
D) If the patient's genome codes for the HER2 receptor. 
E) If the patient's genome codes for the manufacture of Herceptin. 
A) If Herceptin is found in the breast lymph nodes of the patient. 
B) If HER2, administered by injection, is in sufficient concentration. 
C) If the patient's cancer cells have excessive levels of HER2. 
D) If the patient's genome codes for the HER2 receptor. 
E) If the patient's genome codes for the manufacture of Herceptin.

Question 7

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

Accepted Answer

A) they are species specific. 
B) they always lead to the same cellular response. 
C) they amplify the original signal manyfold. 
D) they counter the harmful effects of phosphatases. 
E) the number of molecules used is small and fixed. 
A) they are species specific. 
B) they always lead to the same cellular response. 
C) they amplify the original signal manyfold. 
D) they counter the harmful effects of phosphatases. 
E) the number of molecules used is small and fixed.

Question 8

Protein phosphorylation is commonly involved with all of the following except

Accepted Answer

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

Question 9

Which of the following is true of steroid receptor interactions?

Accepted Answer

A) The receptor molecules are themselves lipids. 
B) The steroid can cross the plasma 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. 
B) The steroid can cross the plasma 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 10

In which of the following ways could signal transduction most probably be explored in research to treat cancer?

Accepted Answer

A) removal of serine/threonine phosphate acceptors from transduction pathways in colon pre-cancerous growths 
B) alteration of protein kinases in cell cycle regulation in order to slow cancer growth 
C) increase in calcium ion uptake into the cytoplasm in order to modulate the effects of environmental carcinogens 
D) expansion of the role of transduction inhibitors in the cells before they give rise to cancer 
E) increase in the concentration of phosphodiesterases in order to produce more AMP 
A) removal of serine/threonine phosphate acceptors from transduction pathways in colon pre-cancerous growths 
B) alteration of protein kinases in cell cycle regulation in order to slow cancer growth 
C) increase in calcium ion uptake into the cytoplasm in order to modulate the effects of environmental carcinogens 
D) expansion of the role of transduction inhibitors in the cells before they give rise to cancer 
E) increase in the concentration of phosphodiesterases in order to produce more AMP

Question 11

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 12

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.
-Where would you expect to find the carboxyl end?

Accepted Answer

A) at the exterior surface 
B) at the cytosol surface 
C) connected with the loop at H5 and H6 
D) between the membrane layers 
E) there is no carboxyl end in proteins 
A) at the exterior surface 
B) at the cytosol surface 
C) connected with the loop at H5 and H6 
D) between the membrane layers 
E) there is no carboxyl end in proteins

Question 13

Which of the following is true of transcription factors?

Accepted Answer

A) They regulate the synthesis of DNA in response to a signal. 
B) They transcribe ATP into cAMP. 
C) They initiate the epinephrine response in animal cells. 
D) They control gene expression. 
E) They regulate the synthesis of lipids in the cytoplasm. 
A) They regulate the synthesis of DNA in response to a signal. 
B) They transcribe ATP into cAMP. 
C) They initiate the epinephrine response in animal cells. 
D) They control gene expression. 
E) They regulate the synthesis of lipids in the cytoplasm.

Question 14

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 15

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 16

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.
-When an excess of the ligand (hormone)is poured through the column after the receptor binding step,what do you expect will occur?

Accepted Answer

A) The ligand will attach to those beads that have the receptor and remain on the column. 
B) The ligand will cause the receptor to be displaced from the beads and eluted out. 
C) The ligand will attach to the bead instead of the receptor. 
D) The ligand will cause the bead to lose its affinity by changing shape. 
E) The reaction will cause a pH change due to electron transfer. 
A) The ligand will attach to those beads that have the receptor and remain on the column. 
B) The ligand will cause the receptor to be displaced from the beads and eluted out. 
C) The ligand will attach to the bead instead of the receptor. 
D) The ligand will cause the bead to lose its affinity by changing shape. 
E) The reaction will cause a pH change due to electron transfer.

Question 17

What does yeast cell mating factor do?

Accepted Answer

A) acts 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 
E) allows two cells with the same mating factor (e.g. a)to mate 
A) acts 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 
E) allows two cells with the same mating factor (e.g. a)to mate

Question 18

Select the appropriate description of apoptosis.

Accepted Answer

A) Apoptosis is regulated by cell surface receptors that signal when a cell has reached its density-dependent limits. 
B) During apoptosis, dying cells leak out their contents, including digestive enzymes that also destroy healthy cells. 
C) During apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell. 
D) Each cell organelle has protein signals that initiate the breakdown of the organelle's components, which leads to cell death. 
E) Apoptosis only occurs in old cells. 
A) Apoptosis is regulated by cell surface receptors that signal when a cell has reached its density-dependent limits. 
B) During apoptosis, dying cells leak out their contents, including digestive enzymes that also destroy healthy cells. 
C) During apoptosis, cellular agents chop up the DNA and fragment the organelles and other cytoplasmic components of a cell. 
D) Each cell organelle has protein signals that initiate the breakdown of the organelle's components, which leads to cell death. 
E) Apoptosis only occurs in old cells.

Question 19

At puberty,an adolescent female body changes in both structure and function of several organ systems,primarily under the influence of changing concentrations of estrogens and other steroid hormones.How can one hormone,such as estrogen,mediate so many effects?

Accepted Answer

A) Estrogen is produced in very large concentration and therefore diffuses widely. 
B) Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding. 
C) Estrogen is kept away from the surface of any cells not able to bind it at the surface. 
D) Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding. 
E) The subcomponents of estrogen, when metabolized, can influence cell response. 
A) Estrogen is produced in very large concentration and therefore diffuses widely. 
B) Estrogen has specific receptors inside several cell types, but each cell responds in the same way to its binding. 
C) Estrogen is kept away from the surface of any cells not able to bind it at the surface. 
D) Estrogen binds to specific receptors inside many kinds of cells, each of which have different responses to its binding. 
E) The subcomponents of estrogen, when metabolized, can influence cell response.

Question 20

Which of the following is usually true for receptors?

Accepted Answer

A) They lead to changes in intracellular ion concentration. 
B) They open and close in response to protein signals. 
C) They are only attached to one membrane surface: exterior or interior. 
D) They preferentially bind with lipid signal molecules. 
E) They change their conformation after binding with signal molecules. 
A) They lead to changes in intracellular ion concentration. 
B) They open and close in response to protein signals. 
C) They are only attached to one membrane surface: exterior or interior. 
D) They preferentially bind with lipid signal molecules. 
E) They change their conformation after binding with signal molecules.

Exam 11: Cell Communication

Lipid-soluble signalling molecules,such as testosterone,cross the membranes of all cells but affect only target cells because

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

Which of the following is true of steroid receptors?

In which of the following ways do plant hormones differ from hormones in animals?

Which of the following describes the events of apoptosis?

Which of the following dictates the use of Herceptin in breast cancer treatment?

Phosphorylation cascades involving a series of protein kinases are useful for cellular signal transduction because

Protein phosphorylation is commonly involved with all of the following except

Which of the following is true of steroid receptor interactions?

In which of the following ways could signal transduction most probably be explored in research to treat cancer?

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

Which of the following is true of transcription factors?

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

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?

What does yeast cell mating factor do?

Select the appropriate description of apoptosis.

At puberty,an adolescent female body changes in both structure and function of several organ systems,primarily under the influence of changing concentrations of estrogens and other steroid hormones.How can one hormone,such as estrogen,mediate so many effects?

Which of the following is usually true for receptors?

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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