Question 1

When the concentration of a ligand is equal to the KD,

Accepted Answer

A)  all of the ligands and receptors are bound to each other.
B)  half of the ligands are bound to receptors.
C)  all of the ligands are bound to receptors.
D)  half of the receptors are bound to ligands.
E)  all of the receptors are bound to ligands.F) A) and E)
G) All of the above D

Question 2

When epinephrine binds to its G-protein linked receptor,

Accepted Answer

A)  adenylyl cyclase is activated producing cAMP.
B)  kinase is activated producing calcium.
C)  enzyme linked receptors is activated producing protein kinase.
D)  kinase is activated producing transcription factor.
E)  phospholipase C is activated producing diacylglyceridE.F) A) and D)
G) A) and C)

Question 3

Which signaling molecule is composed of  α\alphaα , β\betaβ ,and γ\gammaγ subunits?

Accepted Answer

A)  G-protein coupled receptor
B)  ion-channel receptor
C)  tyrosine kinase receptor
D)  G-protein
E)  ligand F) A) and B)
G) None of the above

Question 4

One common feature with G-protein coupled,enzyme-linked,and growth factor receptors is that their activation leads to activation of protein kinases.

Accepted Answer

A) True 
 B)False

Question 5

What do contact-dependent signaling and paracrine signaling have in common?

Accepted Answer

A)  Cells release a signal that affects cells at long distances.
B)  Cells bind a membrane bound signal on a neighboring cell.
C)  Cells release a signal that affects it and neighboring cells.
D)  Cells release a signal that affects neighboring cells.
E)  Cells release a signal through gap junctions to affect neighboring cells.F) A) and E)
G) A) and C)

Question 6

If you add the plant hormone auxin to one side of a plant the cells exposed to the auxin elongate.If you measured auxin levels in plant cells exposed to light what you would you expect to find?

Accepted Answer

A)  They would be higher,causing the plant to bend towards the light.
B)  They would be lower,causing the plant to bend away from the light.
C)  They would be higher,causing the plant to bend away from the light.
D)  They would be lower,causing the plant to bend towards the light.E) B) and D)
F) B) and C)

Question 7

Hormones are released from one cell and act on other cells in distant organs.This is an example of

Accepted Answer

A)  paracrine signaling.
B)  endocrine signaling.
C)  contact-to-contact signaling.
D)  autocrine signaling.
E)  intercellular signaling.F) C) and D)
G) A) and B)

Question 8

When a signal is released from one neuron and it moves to another neuron or to a muscle cell,the signal binds to a

Accepted Answer

A)  ligand-gated ion channel.
B)  voltage-gated ion channel.
C)  nuclear receptor.
D)  enzyme-linked receptor.
E)  G-protein coupled receptor.F) B) and E)
G) C) and E)

Question 9

A key is placed into a keyhole then turned and the door opens.When considering the components of cell signaling,the action of turning the key would best correspond to

Accepted Answer

A)  the concentration of the hormone.
B)  the cell response that occurs when the receptor binds the hormone.
C)  the binding site of the receptor.
D)  conformational change in the receptor once bound to the hormone.
E)  signal transduction that occurs when the receptor binds the hormonE.F) C) and E)
G) B) and D)

Question 10

After being fed glucose a cell increases its intracellular glucose concentrations by

Accepted Answer

A)  increasing membrane glucose receptors.
B)  increasing glucose synthesis in the cell.
C)  decreasing glucose receptors on the cell.
D)  increasing membrane glucose transporters.
E)  decreasing glucose breakdown in the cell.F) B) and E)
G) A) and B)

Question 11

Whether a signaling molecule operates locally or over long distances,it must bind to a specific receptor to elicit a cellular response.

Accepted Answer

A) True 
 B)False

Question 12

If epinephrine increases glycogen metabolism in muscle cells it would have the same function in brain cells.

Accepted Answer

A) True 
 B)False  False

Question 13

Cyclic AMP activates protein kinase C in producing a cell response.

Accepted Answer

A) True 
 B)False

Question 14

A cell secretes a growth factor that binds to receptors on its own membrane preventing it from proliferating.This is an example of

Accepted Answer

A)  direct intercellular signaling.
B)  autocrine signaling.
C)  endocrine signaling.
D)  paracrine signaling.
E)  contact-dependent signaling.F) A) and B)
G) A) and C)

Question 15

G-protein coupled,enzyme-linked,and ligand-gated ion channel receptors are similar in that they

Accepted Answer

A)  associate with a protein bound to GDP or GTP.
B)  are all linked to protein kinase activation.
C)  change their conformation when bound to a hormone.
D)  bind similar hormones.
E)  open ion channels.F) B) and C)
G) D) and E)

Question 16

In some cases,just a few hormone molecules binding to the surface of a cell can trigger a very large response because

Accepted Answer

A)  each hormone can bind to transcription factors simultaneously causing amplification of the signal.
B)  the signal is amplified by activation of transcription factors that each catalyze multiple reactions.
C)  each hormone can bind to multiple receptors simultaneously causing amplification of the signal.
D)  the hormone triggers the cell to release more hormones,amplifying the signal.
E)  the signal is amplified by activation of enzymes that each catalyze multiple reactions.F) A) and E)
G) D) and E)

Question 17

Auxin is a plant hormone that causes cells to shorten and allow plant growing tips to move toward the sun.

Accepted Answer

A) True 
 B)False  False

Question 18

A phosphatase is capable of dephosphorylating molecules.What would this enzyme do in a signal transduction pathway that used a kinase cascade?

Accepted Answer

A)  Phosphorylate a transcription factor.
B)  Serve as a ligand for the receptor.
C)  Activate the cascade.
D)  Phosphorylate a receptor.
E)  Turn off the cascadE.F) B) and D)
G) None of the above

Question 19

A cell secretes a growth factor that binds to receptors on neighboring cells causing them to proliferate.This is an example of

Accepted Answer

A)  paracrine signaling.
B)  direct intercellular signaling.
C)  endocrine signaling.
D)  contact-dependent signaling.
E)  autocrine signaling.F) A) and E)
G) A) and D)

Question 20

Insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake.This is an example of

Accepted Answer

A)  contact-dependent signaling.
B)  direct intercellular signaling.
C)  autocrine signaling.
D)  paracrine signaling.
E)  endocrine signaling.F) B) and E)
G) A) and B)

Exam 8: Cell Communication

When the concentration of a ligand is equal to the KD,

Correct AnswerverifiedD

When epinephrine binds to its G-protein linked receptor,

Correct AnswerverifiedShow Answer

Which signaling molecule is composed of α\alphaα , β\betaβ ,and γ\gammaγ subunits?

Correct AnswerverifiedShow Answer

One common feature with G-protein coupled,enzyme-linked,and growth factor receptors is that their activation leads to activation of protein kinases.

Correct AnswerverifiedShow Answer

What do contact-dependent signaling and paracrine signaling have in common?

Correct AnswerverifiedShow Answer

If you add the plant hormone auxin to one side of a plant the cells exposed to the auxin elongate.If you measured auxin levels in plant cells exposed to light what you would you expect to find?

Correct AnswerverifiedShow Answer

Hormones are released from one cell and act on other cells in distant organs.This is an example of

Correct AnswerverifiedShow Answer

When a signal is released from one neuron and it moves to another neuron or to a muscle cell,the signal binds to a

Correct AnswerverifiedShow Answer

A key is placed into a keyhole then turned and the door opens.When considering the components of cell signaling,the action of turning the key would best correspond to

Correct AnswerverifiedShow Answer

After being fed glucose a cell increases its intracellular glucose concentrations by

Correct AnswerverifiedShow Answer

Whether a signaling molecule operates locally or over long distances,it must bind to a specific receptor to elicit a cellular response.

Correct AnswerverifiedShow Answer

If epinephrine increases glycogen metabolism in muscle cells it would have the same function in brain cells.

Correct AnswerverifiedFalse

Cyclic AMP activates protein kinase C in producing a cell response.

Correct AnswerverifiedShow Answer

A cell secretes a growth factor that binds to receptors on its own membrane preventing it from proliferating.This is an example of

Correct AnswerverifiedShow Answer

G-protein coupled,enzyme-linked,and ligand-gated ion channel receptors are similar in that they

Correct AnswerverifiedShow Answer

In some cases,just a few hormone molecules binding to the surface of a cell can trigger a very large response because

Correct AnswerverifiedShow Answer

Auxin is a plant hormone that causes cells to shorten and allow plant growing tips to move toward the sun.

Correct AnswerverifiedFalse

A phosphatase is capable of dephosphorylating molecules.What would this enzyme do in a signal transduction pathway that used a kinase cascade?

Correct AnswerverifiedShow Answer

A cell secretes a growth factor that binds to receptors on neighboring cells causing them to proliferate.This is an example of

Correct AnswerverifiedShow Answer

Insulin is secreted from the pancreas and acts on muscle cells to increase glucose uptake.This is an example of

Correct AnswerverifiedShow Answer

When the concentration of a ligand is equal to the K_D,

Correct Answer
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Which signaling molecule is composed of $\alpha$ , $\beta$ ,and $\gamma$ subunits?

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False

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False

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