Question 1

Which of the following best explains why cholesterol is important for maintaining membrane fluidity in animal cells at different temperatures?

Accepted Answer

Cholesterol restrains phospholipid movement at warm temperatures and prevents tight packing at cool temperatures.

Question 2

A red blood cell is placed in a solution and begins to swell and eventually bursts. Which of the following best describes the tonicity of the solution relative to the cell?

Accepted Answer

The solution is hypotonic to the cell.

Question 3

Which of the following molecules would most easily diffuse across a pure phospholipid bilayer without the help of a transport protein?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 4

Which of the following statements about membrane proteins is correct?

Accepted Answer

Transmembrane proteins span the entire membrane and are a type of integral protein.

Question 5

A cell is placed in a solution with a higher solute concentration than inside the cell. What will happen to the cell, and why?

Accepted Answer

The cell will lose water because the solution is hypertonic.

Question 6

Which of the following best describes the role of aquaporins in the plasma membrane?

Accepted Answer

They facilitate the passive diffusion of water across the membrane.

Question 7

Which of the following is an example of local signaling in animal cells?

Accepted Answer

Paracrine signaling where growth factors stimulate nearby cells.

Question 8

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

Accepted Answer

Reception $$\rightarrow$$ Transduction $$\rightarrow$$ Response

Question 9

A mutation causes a cell to produce a nonfunctional protein kinase. Which stage of cell signaling is most directly affected?

Accepted Answer

Transduction

Question 10

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

Accepted Answer

GPCRs require GTP to activate the G protein.

Question 11

Which of the following best explains why unsaturated fatty acids increase membrane fluidity?

Accepted Answer

They disrupt Van der Waals interactions due to kinks from double bonds.

Question 12

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Enabling cell-cell recognition by binding to specific molecules.

Question 13

Which of the following scenarios best illustrates the concept of selective permeability?

Accepted Answer

A cell membrane allows oxygen to diffuse but requires a transport protein for glucose.

Question 14

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

Accepted Answer

They open in response to the binding of a specific ligand, allowing ions to pass through.

Question 15

Which of the following best describes the role of second messengers in signal transduction?

Accepted Answer

They are small, nonprotein molecules that amplify and spread the signal within the cell.

Question 16

A researcher adds a molecule that inhibits adenylyl cyclase to a cell culture. Which of the following processes would be directly affected?

Accepted Answer

The conversion of ATP to cAMP.

Question 17

Which of the following best explains why only certain cells respond to a particular hormone like aldosterone?

Accepted Answer

Only those cells have the specific receptor for the hormone.

Question 18

Which of the following is a correct example of long-distance signaling?

Accepted Answer

A hormone released into the bloodstream affecting distant target cells.

Question 19

Which of the following best describes the function of protein phosphatases in signal transduction pathways?

Accepted Answer

They remove phosphate groups from proteins, turning off the signal.

Question 20

A cell is exposed to a toxin that prevents the removal of phosphate groups from proteins. What is the most likely effect on signal transduction pathways in the cell?

Accepted Answer

Proteins will remain active longer than normal, potentially causing excessive cellular responses.

Membrane Transport and Cell Signaling: Study Notes

Guida di studio - Domande di pratica

Study guide - Flashcard