Question 1

Which of the following best describes paracrine signaling in cell communication?

Accepted Answer

Cells release signals that affect only nearby target cells.

Question 2

A neurotransmitter is released from a neuron and binds to a receptor on a muscle cell, causing it to contract. This is an example of which type of cell signaling?

Accepted Answer

Synaptic signaling

Question 3

Which of the following is a correct sequence of events in a typical signal transduction pathway?

Accepted Answer

Reception → Transduction → Response

Question 4

A ligand binds to a G protein-coupled receptor (GPCR) on the cell surface. What is the next immediate step in the signal transduction pathway?

Accepted Answer

The G protein exchanges GDP for GTP and becomes activated.

Question 5

Which of the following best explains why steroid hormones can pass through the plasma membrane?

Accepted Answer

Steroid hormones are lipid-soluble and can diffuse through the lipid bilayer.

Question 6

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

Accepted Answer

cAMP

Question 7

A mutation causes a protein kinase in a signaling pathway to be permanently active. What is a likely consequence?

Accepted Answer

The pathway will be continuously activated, possibly leading to uncontrolled cell division.

Question 8

Which phase of the cell cycle is characterized by DNA replication?

Accepted Answer

S phase

Question 9

During which checkpoint does the cell verify that all chromosomes are properly attached to the spindle before proceeding with division?

Accepted Answer

M checkpoint

Question 10

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

Accepted Answer

Cyclins bind to cyclin-dependent kinases (CDKs) to regulate cell cycle progression.

Question 11

A cell fails to pass the G1 checkpoint due to DNA damage. What is the most likely outcome?

Accepted Answer

The cell will enter a non-dividing state (G0) or undergo apoptosis.

Question 12

Which of the following is an example of positive feedback in biological systems?

Accepted Answer

Release of oxytocin during childbirth increases uterine contractions.

Question 13

Which process ensures that daughter cells receive the correct number of chromosomes during cell division?

Accepted Answer

Mitotic spindle attachment to kinetochores during metaphase.

Question 14

Which of the following best describes the difference between mitosis and meiosis?

Accepted Answer

Mitosis produces genetically identical cells; meiosis produces genetically diverse gametes.

Question 15

Which of the following equations correctly represents the relationship between cyclin concentration and CDK activity?

Accepted Answer

$CDK_{active} = Cyclin 	imes CDK_{inactive}$

Question 16

A researcher adds a drug that blocks the production of cAMP in a cell. Which cellular response is most likely to be affected?

Accepted Answer

Activation of protein kinase A (PKA)

Question 17

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

Accepted Answer

The channel opens or closes, altering ion flow across the membrane.

Question 18

Which of the following best explains why negative feedback is important in biological systems?

Accepted Answer

It helps maintain homeostasis by counteracting deviations from a set point.

Question 19

A cell is exposed to a growth factor that activates a receptor tyrosine kinase (RTK). Which of the following is the most immediate cellular response?

Accepted Answer

Autophosphorylation of the receptor and activation of downstream signaling proteins.

Question 20

Which checkpoint in the cell cycle ensures that DNA has been completely and accurately replicated before mitosis?

Accepted Answer

G2 checkpoint

Cell Communication, Signal Transduction, and Cell Cycle: Study Notes

Study Guide - Practice Questions

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