Question 1

Which of the following best describes the sequence of events in cell signaling?

Accepted Answer

Reception → Transduction → Response

Question 2

Which type of cell signaling involves a signaling molecule traveling through the bloodstream to reach distant target cells?

Accepted Answer

Endocrine signaling

Question 3

A neurotransmitter is released from a neuron and diffuses across a synapse to a target cell. This is an example of:

Accepted Answer

Paracrine signaling

Question 4

Which of the following is TRUE about autocrine signaling?

Accepted Answer

The signaling cell and the responding cell are the same cell.

Question 5

Steroid hormones such as estrogen and testosterone can pass through the cell membrane because they are:

Accepted Answer

Nonpolar molecules

Question 6

Which of the following statements about G protein-coupled receptors (GPCRs) is correct?

Accepted Answer

GPCRs are cell-surface receptors that activate G proteins by binding GTP.

Question 7

What is the main advantage of having multiple steps in a signal transduction pathway?

Accepted Answer

It amplifies the signal and allows for regulation.

Question 8

Which of the following best describes the role of second messengers such as cyclic AMP (cAMP) in cell signaling?

Accepted Answer

They relay signals from receptors on the cell surface to target molecules inside the cell.

Question 9

A mutation in the Kit receptor kinase leads to a lack of pigment in hair and skin. This is most likely due to:

Accepted Answer

Failure to activate the phosphorylation cascade required for pigment production.

Question 10

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

Accepted Answer

$$\mathrm{ATP} \rightarrow \mathrm{cAMP} + \mathrm{PP_i}$$

Question 11

Which signaling mechanism requires direct physical contact between two cells?

Accepted Answer

Contact-dependent signaling

Question 12

Which of the following is a cytoplasmic response to cell signaling?

Accepted Answer

Stimulation of glycogen breakdown by epinephrine

Question 13

What happens to a G protein after the ligand dissociates from the G protein-coupled receptor?

Accepted Answer

It hydrolyzes GTP to GDP and becomes inactive.

Question 14

Which of the following best explains why polar signaling molecules require cell-surface receptors?

Accepted Answer

They cannot cross the hydrophobic core of the lipid bilayer.

Question 15

Which of the following is a function of scaffolding proteins in signal transduction?

Accepted Answer

They organize relay proteins to increase the efficiency of signal transduction.

Question 16

Which of the following is an example of a second messenger in a signaling pathway?

Accepted Answer

cAMP

Question 17

A cell receives a signal that leads to the release of calcium ions from the endoplasmic reticulum. Which second messenger is most likely involved in this process?

Accepted Answer

IP$$_3$$

Question 18

Which of the following is a possible outcome if the termination phase of cell signaling fails?

Accepted Answer

The cell may have prolonged or inappropriate responses.

Question 19

Which of the following best describes the role of phosphorylation cascades in signal transduction?

Accepted Answer

They amplify the signal by activating multiple proteins in sequence.

Question 20

Which of the following is most likely to occur if a cell-surface receptor is mutated so it cannot bind its ligand?

Accepted Answer

The signal transduction pathway will not be activated.

Cell Communication: Mechanisms and Pathways

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