Question 1

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

Accepted Answer

A signaling cell releases molecules that affect only nearby target cells.

Question 2

Which type of receptor is most likely to be activated by a steroid hormone such as aldosterone?

Accepted Answer

An intracellular receptor located in the cytoplasm or nucleus.

Question 3

What is the primary function of receptor tyrosine kinases (RTKs) in cell signaling?

Accepted Answer

They catalyze the transfer of phosphate groups from ATP to specific tyrosine residues on target proteins.

Question 4

Which of the following is a key difference between endocrine and synaptic signaling?

Accepted Answer

Endocrine signaling involves hormones traveling through the bloodstream, while synaptic signaling involves neurotransmitters crossing a synapse.

Question 5

A mutation causes a G protein to be unable to hydrolyze GTP to GDP. What is the most likely consequence for the cell?

Accepted Answer

The G protein will remain active, continuously stimulating its downstream pathway.

Question 6

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.

Question 7

Which of the following is a real-life example of apoptosis during human development?

Accepted Answer

The removal of interdigital tissue to separate fingers and toes.

Question 8

A scientist observes that a certain drug blocks the function of caspases in a cell. What process is most likely to be inhibited?

Accepted Answer

Apoptosis, or programmed cell death.

Question 9

Which of the following best describes the sequence of events in a typical cell signaling pathway?

Accepted Answer

Signal reception → Signal transduction → Cellular response

Question 10

Which of the following statements about ligand-gated ion channel receptors is correct?

Accepted Answer

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

Question 11

Which of the following equations best represents the hydrolysis of ATP during receptor tyrosine kinase activation?

Accepted Answer

$$ \mathrm{ATP} \rightarrow \mathrm{ADP} + \mathrm{P_i} $$

Question 12

A patient is given a drug that mimics the action of a neurotransmitter at a synapse. Which type of signaling is being affected?

Accepted Answer

Synaptic signaling

Question 13

Which of the following is a plausible consequence of abnormal receptor tyrosine kinase (RTK) activity in human cells?

Accepted Answer

Uncontrolled cell growth leading to cancer

Question 14

Which of the following best explains why apoptosis is important for multicellular organisms?

Accepted Answer

It removes damaged or unnecessary cells without harming neighboring cells.

Question 15

Which of the following is true about the specificity of cell signaling?

Accepted Answer

A cell's response to a signal depends on the presence of a specific receptor for that signal.

Question 16

Which of the following best describes the role of GTP in G protein-coupled receptor (GPCR) signaling?

Accepted Answer

GTP binds to the G protein, activating it to transmit the signal to downstream effectors.

Question 17

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

Accepted Answer

An intracellular receptor in the cytoplasm or nucleus

Question 18

Which of the following is a correct sequence of events for the activation of a receptor tyrosine kinase (RTK)?

Accepted Answer

Ligand binding → Dimerization → Phosphorylation → Activation of relay proteins

Question 19

Which of the following best describes the function of caspases in apoptosis?

Accepted Answer

They are proteases that cleave cellular proteins during programmed cell death.

Cell Communication and Signal Transduction

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