Question 1

Which of the following best describes the three stages of cell signaling as shown in the first image?

Accepted Answer

Reception, transduction, and response

Question 2

A researcher discovers a new drug that binds to the β2-adrenergic receptor (as shown in the second image) and mimics the natural ligand. What type of molecule is this drug most likely to be?

Accepted Answer

An agonist

Question 3

Which of the following statements about G protein-coupled receptors (GPCRs), as depicted in the third image, is correct?

Accepted Answer

They span the plasma membrane and interact with G proteins inside the cell.

Question 4

Referencing the fourth image, what is the primary function of receptor tyrosine kinases (RTKs) after ligand binding?

Accepted Answer

They dimerize and autophosphorylate, triggering multiple signal transduction pathways.

Question 5

Which of the following best explains the mechanism of ligand-gated ion channel receptors as shown in the fifth image?

Accepted Answer

They open or close in response to the binding of a signaling molecule, allowing specific ions to pass through the membrane.

Question 6

Based on the sixth image, which of the following statements about intracellular receptors is correct?

Accepted Answer

They bind small or hydrophobic molecules, such as steroid hormones, and can directly regulate gene expression.

Question 7

In the seventh image, which enzyme is responsible for converting ATP to cAMP, a common second messenger?

Accepted Answer

Adenylyl cyclase

Question 8

According to the eighth image, why is calcium ($$\mathrm{Ca$$^{2+}$$}) $$considered an effective second messenger in cell signaling?

Accepted Answer

Its cytosolic concentration is normally much lower than outside the cell, so small changes can have large effects.

Question 9

Which of the following best describes the concept of signal amplification in cell signaling pathways?

Accepted Answer

A single signaling molecule can activate many molecules at each step, resulting in a large cellular response.

Question 10

A mutation causes a cell to lack scaffolding proteins. Which aspect of cell signaling is most likely to be affected?

Accepted Answer

The overall efficiency of the response

Question 11

Which of the following scenarios best illustrates the concept of pathway branching and cross-talk in cell signaling, as shown in the ninth image?

Accepted Answer

A single signal leads to activation of two different responses in the same cell.

Question 12

Which of the following is NOT a typical function of second messengers in cell signaling?

Accepted Answer

Directly binding to DNA to regulate gene expression

Question 13

A cell is exposed to a hormone that cannot cross the plasma membrane. Which type of receptor is most likely to mediate the cell's response?

Accepted Answer

A G protein-coupled receptor

Question 14

Which of the following best explains why apoptosis is important during the development of human hands and feet?

Accepted Answer

It removes unnecessary cells, shaping the digits by programmed cell death.

Question 15

Which of the following is a correct statement about the termination of a cell signaling response?

Accepted Answer

Unbound receptors revert to an inactive state when the external signal decreases.

Question 16

A scientist observes that a cell responds to a signal by increasing the transcription of a specific gene. Which step of cell signaling is most directly responsible for this outcome?

Accepted Answer

Cellular response

Question 17

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

Accepted Answer

They transfer phosphate groups from ATP to proteins, often activating them.

Question 18

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

Accepted Answer

Growth factors stimulating nearby cells to divide during wound healing.

Question 19

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

Accepted Answer

The G protein will remain active, potentially leading to continuous signaling.

Question 20

Which of the following best explains why the same signaling molecule can produce different responses in different cell types?

Accepted Answer

Different cells have different proteins and pathways that interpret the signal.

Cell Communication and Signal Transduction

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