Question 1

Which of the following best describes the three main stages of cell signaling?

Accepted Answer

Reception, transduction, and response

Question 2

A peptide hormone such as insulin is released into the bloodstream. Which of the following statements about its transport and action is correct?

Accepted Answer

It dissolves freely in plasma and binds to cell-surface receptors.

Question 3

Which of the following would most likely disrupt a G protein-coupled receptor (GPCR) signaling pathway?

Accepted Answer

A lack of GTP in the cell

Question 4

Steroid hormones such as aldosterone typically exert their effects by:

Accepted Answer

Acting as transcription factors after binding intracellular receptors

Question 5

Which of the following best explains why only certain cells respond to a specific hormone?

Accepted Answer

Only cells with the matching receptor for the hormone can respond.

Question 6

In the fight-or-flight response, epinephrine triggers the breakdown of glycogen in muscle cells. Which step in the signaling pathway is responsible for amplifying the signal so that one hormone molecule can lead to the production of millions of glucose molecules?

Accepted Answer

Each enzyme in the cascade activates many molecules of the next enzyme.

Question 7

Which of the following is a correct sequence of events in a G protein-coupled receptor (GPCR) pathway?

Accepted Answer

Ligand binds GPCR → G protein activated (GTP replaces GDP) → Adenylyl cyclase activated → cAMP produced

Question 8

A cell is exposed to a water-soluble hormone. Which of the following is most likely to occur?

Accepted Answer

The hormone binds to a receptor on the cell surface and activates a second messenger.

Question 9

Which of the following best describes the role of protein kinases in a phosphorylation cascade?

Accepted Answer

They add phosphate groups to proteins, activating or inactivating them.

Question 10

A mutation prevents the production of phosphodiesterase in a cell. What is the most likely effect on a signaling pathway that uses cAMP as a second messenger?

Accepted Answer

cAMP levels would remain high, prolonging the cellular response.

Question 11

Which of the following is an example of local signaling in animal cells?

Accepted Answer

A neuron releasing neurotransmitters at a synapse

Question 12

Which of the following statements about ligand-gated ion channel receptors is correct?

Accepted Answer

They open or close in response to binding a specific signaling molecule, allowing ions to flow across the membrane.

Question 13

A cell is exposed to a growth factor that binds to a receptor tyrosine kinase (RTK). Which of the following is a likely outcome?

Accepted Answer

Multiple signal transduction pathways are activated, leading to cell growth and division.

Question 14

Which of the following best explains why the same hormone can produce different responses in different cell types?

Accepted Answer

Different cells have different collections of receptors and internal proteins.

Question 15

Which equation correctly represents the conversion of ATP to cAMP by adenylyl cyclase?

Accepted Answer

$$\mathrm{ATP} \xrightarrow{	ext{adenylyl cyclase}} \mathrm{cAMP} + \mathrm{PP_i}$$

Question 16

Which of the following is a direct cytoplasmic response to epinephrine signaling in a liver cell?

Accepted Answer

Breakdown of glycogen to glucose-1-phosphate

Question 17

If a cell lacks ATP at the start of a signal transduction cascade, what is the most likely consequence?

Accepted Answer

Protein kinases cannot phosphorylate target proteins, so the signal is not relayed.

Question 18

Which of the following best describes the function of protein phosphatases in cell signaling?

Accepted Answer

They remove phosphate groups from proteins, turning off the signal.

Question 19

In the context of diabetes, what is the primary role of insulin in blood glucose regulation?

Accepted Answer

It facilitates the uptake of glucose into muscle and liver cells.

Question 20

Which of the following is a real-life example of long-distance signaling in animals?

Accepted Answer

The release of epinephrine from the adrenal glands into the bloodstream during stress

Cell Signaling and Communication: Mechanisms and Examples

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