Question 1

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

Accepted Answer

Reception, transduction, response

Question 2

Epinephrine is released into the bloodstream during a 'fight or flight' response. Which of the following is the correct sequence of events that leads to the breakdown of glycogen in muscle cells?

Accepted Answer

Epinephrine binds to a GPCR → G protein activates adenylyl cyclase → cAMP produced → Protein kinase A activated → Glycogen phosphorylase activated

Question 3

Which of the following statements about peptide hormones is correct?

Accepted Answer

They are water-soluble and bind to cell-surface receptors.

Question 4

A mutation prevents a G protein from hydrolyzing GTP to GDP. What is the most likely consequence for the cell signaling pathway?

Accepted Answer

The pathway will remain active longer than normal, potentially causing excessive cellular responses.

Question 5

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

Accepted Answer

Only cells with the specific receptor for that hormone can respond.

Question 6

Which of the following is a key feature of signal amplification in a cell signaling pathway?

Accepted Answer

One signaling molecule can lead to the activation of many molecules at each step, resulting in a large cellular response.

Question 7

Which type of receptor is most likely to be activated by a steroid hormone such as aldosterone?

Accepted Answer

Intracellular receptor

Question 8

A patient has a genetic defect that prevents the production of adenylyl cyclase. Which step in the epinephrine signaling pathway would be directly affected?

Accepted Answer

Conversion of ATP to cAMP

Question 9

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

Accepted Answer

They transfer phosphate groups from ATP to target proteins, activating or inactivating them.

Question 10

Which of the following scenarios illustrates paracrine signaling?

Accepted Answer

A cell releases growth factors that stimulate nearby cells to divide.

Question 11

Which of the following is a correct statement about second messengers?

Accepted Answer

They are small, non-protein molecules that relay signals inside the cell.

Question 12

Which of the following would most likely occur if phosphodiesterase is inhibited in a cell?

Accepted Answer

cAMP levels would remain elevated, prolonging the cellular response.

Question 13

Which of the following is a direct result of ligand binding to a ligand-gated ion channel receptor?

Accepted Answer

The channel opens, allowing specific ions to flow across the membrane.

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 of the following is a likely consequence if a cell lacks protein phosphatases?

Accepted Answer

Proteins in the signaling pathway would remain phosphorylated and active longer than normal.

Question 16

Which of the following best describes the function of insulin in blood glucose regulation?

Accepted Answer

It promotes the uptake of glucose into muscle and liver cells, lowering blood glucose levels.

Question 17

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 cell-surface receptor and activates a second messenger pathway.

Question 18

Which of the following is a real-life example of signal transduction involving a phosphorylation cascade?

Accepted Answer

A growth factor binding to its receptor and activating a series of kinases that lead to cell division.

Question 19

Which of the following steps is necessary for a cell to reset its signaling pathway after activation?

Accepted Answer

Removal of the ligand, hydrolysis of GTP to GDP, dephosphorylation of proteins, and breakdown of second messengers.

Cell Communication and Signaling: Mechanisms and Examples

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