Question 1

Which of the following best describes the role of gap junctions in cell-to-cell communication?

Accepted Answer

They allow direct cytoplasmic exchange of ions and small molecules between adjacent cells.

Question 2

A lipophilic signal molecule is most likely to bind to which type of receptor?

Accepted Answer

A cytosolic or nuclear receptor inside the cell.

Question 3

Which of the following is a correct sequence for a basic signal transduction pathway?

Accepted Answer

Ligand binds receptor \rightarrow Receptor activates intracellular signal molecules \rightarrow Target proteins are modified \rightarrow Cellular response

Question 4

Which second messenger is produced by the action of adenylyl cyclase on ATP?

Accepted Answer

cAMP

Question 5

A cell exposed to epinephrine responds by activating a cascade that ultimately leads to glycogen breakdown. Which pathway is most likely involved?

Accepted Answer

G protein-coupled receptor \rightarrow Adenylyl cyclase \rightarrow cAMP \rightarrow Protein kinase A \rightarrow Phosphorylation of target proteins

Question 6

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

Accepted Answer

Only cells with specific receptors for the hormone can respond.

Question 7

Which of the following is a characteristic of G protein-coupled receptors (GPCRs)?

Accepted Answer

They activate intracellular G proteins, which can open ion channels or alter enzyme activity.

Question 8

Which molecule acts as both a neurotransmitter and a neuromodulator in the brain, and is produced by endothelial cells to cause vasodilation?

Accepted Answer

Nitric oxide (NO)

Question 9

What is the effect of up-regulation of receptors on a cell’s sensitivity to a ligand?

Accepted Answer

It increases the cell’s sensitivity to the ligand.

Question 10

Which of the following best describes the function of protein kinases in signal transduction pathways?

Accepted Answer

They transfer a phosphate group from ATP to a protein, altering the protein’s activity.

Question 11

A cell releases a signal molecule that binds to receptors on the same cell. This is an example of:

Accepted Answer

Autocrine signaling

Question 12

Which of the following is a plausible outcome of activating the phospholipase C (PL-C) pathway?

Accepted Answer

Release of $$Ca^{2+}$$ from intracellular stores and activation of protein kinase C (PK-C)

Question 13

Which of the following best describes the difference between agonists and antagonists in cell signaling?

Accepted Answer

Agonists activate receptors, while antagonists block receptor activation.

Question 14

Which of the following is a correct description of a feedback loop in physiological control pathways?

Accepted Answer

A process in which the response feeds back to influence the initial stimulus.

Question 15

Which of the following is a real-world example of paracrine signaling?

Accepted Answer

Interferon released by a virus-infected cell signals neighboring cells to put up barriers.

Question 16

Which of the following best describes the action of leukotrienes produced in the arachidonic acid cascade?

Accepted Answer

They play a role in asthma and anaphylaxis.

Question 17

Which of the following is a plausible effect of a beta receptor being activated by its ligand?

Accepted Answer

Vasodilation

Question 18

Which of the following best describes the function of amplifier enzymes in signal transduction?

Accepted Answer

They generate large numbers of second messengers from a single ligand-receptor interaction.

Question 19

Which of the following is a correct description of the effect of prostaglandins?

Accepted Answer

They are involved in sleep, inflammation, pain, and fever.

Cell Communication, Integration, and Homeostasis: Chapter 6 Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards