Question 1

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 2

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 3

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 4

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 5

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 6

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 7

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.
-Beta 2 antagonist drugs might also be used most effectively for which of the following?

Accepted Answer

A) cardiac arrhythmias 
B) increased gastric acid production 
C) neuropathy of the extremities 
D) increasing low blood pressure 
E) decreasing peristalsis 
A) cardiac arrhythmias 
B) increased gastric acid production 
C) neuropathy of the extremities 
D) increasing low blood pressure 
E) decreasing peristalsis

Question 8

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of

Accepted Answer

A) phosphorylated proteins. 
B) GTP. 
C) cAMP. 
D) adenylyl cyclase. 
E) activated G proteins. 
A) phosphorylated proteins. 
B) GTP. 
C) cAMP. 
D) adenylyl cyclase. 
E) activated G proteins.

Question 9

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 10

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.

Question 11

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 12

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 13

Use the following figure to answer the questions below.
  
-In the above diagram, the structure labelled D 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 14

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 15

What is most likely to happen to an animal's target cells that lack receptors for local regulators?

Accepted Answer

A) They might compensate by receiving nutrients via a factor. 
B) They could develop normally in response to neurotransmitters instead. 
C) They could divide but never reach full size. 
D) They might 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 might compensate by receiving nutrients via a factor. 
B) They could develop normally in response to neurotransmitters instead. 
C) They could divide but never reach full size. 
D) They might 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 16

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 17

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.

Exam 11: Cell Communication

The structure labelled A is

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

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

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

Protein phosphorylation is commonly involved with all of the following except

Caffeine is an inhibitor of phosphodiesterase. Therefore, the cells of a person who has recently consumed coffee would have increased levels of

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

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

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

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

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

Which of the following is a correct association?

What is most likely to happen to an animal's target cells that lack receptors for local regulators?

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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