Question 1

Which of the following best describes the main difference in how steroid and nonsteroid hormones interact with their target cells?

Accepted Answer

Steroid hormones cross the cell membrane and bind to intracellular receptors, while nonsteroid hormones bind to receptors on the cell surface.

Question 2

A cell receives a signal from a hormone that leads to the activation of a phosphorylation cascade. Which enzyme is responsible for removing phosphate groups to deactivate the signal?

Accepted Answer

Phosphatase

Question 3

Which of the following is a likely cellular response to a steroid hormone such as testosterone in a target cell?

Accepted Answer

Activation of genes leading to the synthesis of new proteins

Question 4

Why do different target cells respond differently to the same hormone, such as adrenaline?

Accepted Answer

Different target cells have different components in their signal transduction pathways.

Question 5

Which of the following is NOT a possible effect of a steroid hormone on a non-target cell?

Accepted Answer

No effect on the cell

Question 6

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

Accepted Answer

Direct cytoplasmic connection between adjacent cells

Question 7

Which of the following best explains why phosphorylation cascades are useful in signal transduction?

Accepted Answer

They allow the signal to be amplified many times.

Question 8

A patient is given a beta-blocker to prevent heart attacks. What is the most direct effect of this drug on heart cells?

Accepted Answer

It blocks the receptors for adrenaline/epinephrine on heart cells.

Question 9

Which equation best represents the amplification of a signal in a phosphorylation cascade, where each kinase activates 10 downstream kinases over 3 steps?

Accepted Answer

$$10^3 = 1000$

Question 10

Which of the following is a second messenger commonly involved in signal transduction pathways?

Accepted Answer

cAMP (cyclic adenosine monophosphate)

Question 11

A mutation causes a cell to produce fewer hormone receptors. What is the most likely consequence?

Accepted Answer

The cell will become less sensitive to the hormone.

Question 12

Which of the following is true about quorum sensing in bacteria?

Accepted Answer

It allows bacteria to sense population density and coordinate group behaviors.

Question 13

Which of the following is most likely to occur when a nonsteroid hormone binds to its receptor on the cell surface?

Accepted Answer

Activation of a signal transduction pathway involving second messengers

Question 14

Which of the following is a correct sequence of events for a steroid hormone acting on a target cell?

Accepted Answer

Hormone enters cell $$\rightarrow$$ binds to intracellular receptor $$\rightarrow$$ activates gene expression $$\rightarrow$$ protein synthesis

Question 15

Which of the following is NOT a function of protein kinases in signal transduction?

Accepted Answer

Removing phosphate groups from proteins

Question 16

A cell exposed to cholera toxin cannot deactivate its signal transduction pathway. What is the most likely physiological consequence?

Accepted Answer

Continuous secretion of chloride ions and water into the intestines, leading to diarrhea and dehydration

Question 17

Which of the following statements about hormone signaling is correct?

Accepted Answer

Hormones can reach almost every cell in the body, but only target cells with the appropriate receptor will respond.

Question 18

Which of the following is an example of crosstalk in cell signaling?

Accepted Answer

A signaling pathway stimulates or inhibits another pathway within the same cell.

Question 19

Which of the following is most likely to occur if a cell's receptors are blocked by a drug?

Accepted Answer

The cell will not respond to the signaling molecule.

Question 20

Which of the following best explains why signal transduction pathways often involve second messengers?

Accepted Answer

Second messengers help relay and amplify the signal inside the cell.

Cell-Cell Communication and Hormonal Signaling in Biology

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