Question 1

Which of the following best describes the role of a ligand in cell communication?

Accepted Answer

A ligand is a molecule that binds to a receptor to initiate a cellular response.

Question 2

A researcher observes that a cell responds to a hormone only when the hormone is present in the extracellular fluid. Which type of signaling is most likely occurring?

Accepted Answer

Endocrine signaling

Question 3

Which of the following is an example of a negative feedback mechanism in biological systems?

Accepted Answer

Release of insulin to lower blood glucose levels

Question 4

A mutation causes a cell to ignore signals that normally inhibit cell division. Which phase of the cell cycle is most likely affected?

Accepted Answer

G1 checkpoint

Question 5

Which of the following best explains why phosphorylation cascades are common in signal transduction pathways?

Accepted Answer

They allow for the rapid amplification of a signal.

Question 6

A cell is exposed to a toxin that blocks the function of G-protein coupled receptors (GPCRs). Which process would be most directly affected?

Accepted Answer

Transduction of extracellular signals into intracellular responses

Question 7

Which equation best represents the relationship between the concentration of a ligand ($$[L]$$), the number of receptors ($$R$$), and the likelihood of a cellular response ($$P$$)?

Accepted Answer

$$P = [L] 	imes R$$

Question 8

During which phase of the cell cycle does DNA replication occur?

Accepted Answer

S phase

Question 9

A scientist observes that a cell fails to divide even though it has duplicated its DNA and grown in size. Which checkpoint is most likely preventing the cell from entering mitosis?

Accepted Answer

G2 checkpoint

Question 10

Which of the following scenarios best illustrates positive feedback?

Accepted Answer

The release of oxytocin during labor increases uterine contractions, which causes more oxytocin to be released.

Question 11

Which of the following best describes the function of cyclins in the cell cycle?

Accepted Answer

Cyclins are signaling molecules that regulate the progression of cells through the cell cycle.

Question 12

A cell receives a signal that triggers the activation of a kinase, which then activates another kinase, and so on. What is this process called?

Accepted Answer

Phosphorylation cascade

Question 13

Which of the following is a direct result of a cell failing to pass the M checkpoint during mitosis?

Accepted Answer

The cell will not proceed to cytokinesis.

Question 14

Which of the following best explains why cancer cells often have mutations in genes that regulate the cell cycle?

Accepted Answer

These mutations allow uncontrolled cell division.

Question 15

A cell uses a second messenger system to amplify a signal received at the membrane. Which molecule is most likely acting as the second messenger?

Accepted Answer

cAMP

Question 16

Which of the following is an example of direct cell-to-cell communication?

Accepted Answer

Gap junctions between cardiac muscle cells

Question 17

A mutation in a receptor protein prevents it from binding its ligand. What is the most likely consequence for the cell?

Accepted Answer

The cell will not respond to the external signal.

Question 18

Which of the following best describes the role of checkpoints in the cell cycle?

Accepted Answer

They ensure that the cell cycle progresses only when certain conditions are met.

Question 19

A scientist adds a drug to cells that prevents the breakdown of cyclin proteins. What is the most likely effect on the cell cycle?

Accepted Answer

The cell cycle will proceed without regulation, possibly leading to uncontrolled division.

Question 20

Which of the following best explains why signal transduction pathways often involve multiple steps?

Accepted Answer

Multiple steps allow for amplification and regulation of the signal.

Cell Communication and Cell Cycle: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards