Question 1

Which of the following best describes the sequence of events in cell signaling that enables an impala to escape from a predator?

Accepted Answer

Signal reception, signal transduction, cellular response

Question 2

A hormone such as epinephrine triggers the breakdown of glycogen in muscle cells. Which of the following best explains why only certain cells respond to epinephrine?

Accepted Answer

Only cells with specific receptors for epinephrine can respond to the hormone.

Question 3

Which of the following is NOT a type of cell signaling described in the study materials?

Accepted Answer

Photosynthetic signaling

Question 4

Gap junctions in animal cells and plasmodesmata in plant cells are examples of which type of cell communication?

Accepted Answer

Direct contact signaling

Question 5

Which of the following statements about G protein-coupled receptors (GPCRs) is correct?

Accepted Answer

They are transmembrane proteins that transmit signals from outside to inside the cell.

Question 6

A scientist is studying a signaling pathway in which a signal molecule binds to a receptor, activating a G protein, which then activates adenylyl cyclase. What is the immediate product of adenylyl cyclase activity?

Accepted Answer

Cyclic AMP ($cAMP$)

Question 7

Which of the following best describes a phosphorylation cascade?

Accepted Answer

A series of proteins are activated by the addition of phosphate groups, amplifying the signal.

Question 8

In the context of cell signaling, what is the primary function of second messengers such as $cAMP$?

Accepted Answer

To relay and amplify the signal from the receptor to target molecules inside the cell

Question 9

A mutation prevents a muscle cell from producing protein kinases. Which step in the signal transduction pathway would be most directly affected?

Accepted Answer

The phosphorylation cascade that amplifies the signal

Question 10

Which of the following scenarios best illustrates paracrine signaling?

Accepted Answer

A cell releases a local regulator that diffuses to nearby target cells.

Question 11

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

Accepted Answer

A cell can only respond to a signal if it has a receptor specific to that signal.

Question 12

Which of the following best explains why the same hormone can have different effects in different cell types?

Accepted Answer

Different cell types may have different receptors or relay proteins, leading to different responses.

Question 13

A researcher adds a drug that blocks the function of adenylyl cyclase in a cell. Which of the following would most likely be observed?

Accepted Answer

The cell would fail to produce $cAMP$ in response to a signal.

Question 14

Which of the following is an example of a cellular response to a signal transduction pathway?

Accepted Answer

Activation of an enzyme that breaks down glycogen

Question 15

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

Accepted Answer

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

Question 16

A patient has a genetic disorder that prevents the formation of gap junctions in heart muscle cells. Which of the following would most likely be affected?

Accepted Answer

Direct electrical communication between heart muscle cells

Question 17

Which of the following equations best represents the conversion catalyzed by adenylyl cyclase in a signal transduction pathway?

Accepted Answer

$ATP \rightarrow cAMP + PP_i$

Question 18

In a scenario where a signaling molecule is hydrophobic, which of the following is most likely true about its receptor?

Accepted Answer

The receptor is located inside the cytoplasm or nucleus.

Question 19

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

Accepted Answer

Multiple steps allow amplification and regulation of the signal.

Question 20

A mutation causes a receptor tyrosine kinase to be permanently active, even without a signaling molecule. Which of the following is a likely consequence?

Accepted Answer

Uncontrolled cell growth due to constant activation of signaling pathways

Cell Communication and Signal Transduction

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