Question 1

Which of the following best describes paracrine signaling in animal cells?

Accepted Answer

A signaling cell releases molecules that only affect nearby target cells within a few cell diameters.

Question 2

Which of the following is NOT a typical example of a signal that cells can interpret?

Accepted Answer

Sound waves

Question 3

A mutation causes a G protein-coupled receptor (GPCR) to remain permanently active, even in the absence of a signaling molecule. What is the most likely consequence for the cell?

Accepted Answer

The cell will continuously activate downstream signaling pathways, potentially leading to diseases such as cancer.

Question 4

Which of the following statements about receptor tyrosine kinases (RTKs) is correct?

Accepted Answer

RTKs dimerize and autophosphorylate upon ligand binding, triggering a cascade of cellular responses.

Question 5

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

Accepted Answer

Only cells with the specific receptor for that hormone can respond to it.

Question 6

Which of the following is a correct sequence of the three stages of cell signaling?

Accepted Answer

Reception → Transduction → Response

Question 7

A researcher discovers a new signaling molecule that is small, hydrophobic, and can easily cross the plasma membrane. Which type of receptor is this molecule most likely to bind?

Accepted Answer

Intracellular receptor

Question 8

Which of the following is a function of second messengers in signal transduction pathways?

Accepted Answer

They amplify the signal by rapidly spreading it throughout the cell.

Question 9

Which of the following best describes the role of scaffolding proteins in cell signaling?

Accepted Answer

They increase the efficiency of signal transduction by holding multiple relay proteins together.

Question 10

A patient is treated with Herceptin, a drug that targets the HER2 receptor. What type of receptor is HER2, and what disease is this treatment most associated with?

Accepted Answer

HER2 is a receptor tyrosine kinase; treatment is for breast cancer.

Question 11

Which of the following is an example of long-distance signaling in animals?

Accepted Answer

Hormone secretion into the bloodstream

Question 12

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

Accepted Answer

A single signaling molecule can trigger the activation of many molecules at each step of the pathway, resulting in a large cellular response.

Question 13

Which of the following is a likely cellular response to a signal transduction pathway that ends in the nucleus?

Accepted Answer

Activation of gene transcription

Question 14

Which of the following is true about apoptosis?

Accepted Answer

It is a programmed cell death process that protects neighboring cells from damage.

Question 15

Which of the following equations best represents the activation of a G protein by a GPCR?

Accepted Answer

$$\mathrm{G_{protein} \cdot GDP + GPCR_{active} \rightarrow G_{protein} \cdot GTP}$$

Question 16

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

Accepted Answer

Growth factors released by a cell stimulating nearby cells to divide during wound healing

Question 17

Which of the following is a common feature of both prokaryotic and eukaryotic cell signaling mechanisms?

Accepted Answer

Use of chemical signals to communicate with other cells

Question 18

A scientist observes that a signaling pathway in a cell is not terminated properly, leading to continuous cell division. Which of the following is the most likely explanation?

Accepted Answer

The signal transduction pathway cannot be reversed, so the signal is not terminated.

Question 19

Which of the following best describes the specificity of a cell's response to a signal?

Accepted Answer

A cell's response depends on its unique collection of receptor and relay proteins.

Cell Communication: Mechanisms and Pathways

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