Q: Which of the following equations best represents the free energy change ($\Delta G$) for the movement of a solute across a membrane?

$\Delta G = RT \ln \left( \frac{[C]_\text{in}}{[C]_\text{out}} \right)$

Question 1

Which of the following best explains why biological membranes are effective permeability barriers?

Accepted Answer

Their interior is hydrophobic, preventing the free passage of most polar molecules.

Question 2

A researcher observes that a certain membrane protein can be removed from the membrane by changing the pH or ionic strength of the solution. Which type of membrane protein is this most likely to be?

Accepted Answer

Peripheral membrane protein

Question 3

Which of the following statements about the fluid mosaic model of membrane structure is correct?

Accepted Answer

The membrane consists of a fluid lipid bilayer with proteins embedded in or associated with the bilayer.

Question 4

Which of the following changes would most likely increase the fluidity of a cell membrane at low temperature?

Accepted Answer

Decreasing the amount of cholesterol below 50% of membrane lipids

Question 5

A mutation causes a membrane protein to lose all hydrophobic amino acid residues. What is the most likely consequence for the protein's localization?

Accepted Answer

It will associate weakly with the membrane surface as a peripheral protein.

Question 6

Which of the following best describes the function of glycoproteins in the plasma membrane?

Accepted Answer

They play a key role in cell-cell recognition and signaling.

Question 7

A red blood cell is placed in a solution and begins to swell and eventually bursts. Which property of the plasma membrane is being challenged in this scenario?

Accepted Answer

The membrane's ability to maintain chemical disequilibrium by selective permeability

Question 8

Which of the following is a correct statement about the Na+/K+ ATPase pump?

Accepted Answer

It uses ATP to move Na+ out of the cell and K+ into the cell, both against their concentration gradients.

Question 9

Which of the following best explains why membrane asymmetry is functionally important?

Accepted Answer

It enables specific recognition and signaling functions on the outer surface of the membrane.

Question 10

A scientist is studying a membrane protein that forms a pore allowing ions to pass through the membrane only when a specific voltage is reached. This protein is best classified as:

Accepted Answer

A voltage-gated ion channel

Question 11

Which of the following equations best represents the free energy change ($\Delta G$) for the movement of a solute across a membrane?

Accepted Answer

$\Delta G = RT \ln \left( \frac{[C]_	ext{in}}{[C]_	ext{out}} ight)$

Question 12

Which of the following is a real-life example of the importance of glycolipids in the plasma membrane?

Accepted Answer

The ABO blood group system depends on structural differences in glycolipids on red blood cells.

Question 13

Which of the following best describes the role of cholesterol in animal cell membranes?

Accepted Answer

At low concentrations, it acts as a spacer and increases fluidity; at high concentrations, it decreases fluidity.

Question 14

A membrane protein is found to be covalently attached to a glycosylphosphatidylinositol (GPI) anchor. Where is this protein most likely located?

Accepted Answer

On the outer surface of the plasma membrane

Question 15

Which of the following is a key difference between channel proteins and carrier proteins in membrane transport?

Accepted Answer

Channel proteins provide a hydrophilic pathway for specific ions or molecules to diffuse rapidly across the membrane.

Question 16

Which of the following best describes the function of tight junctions in animal cells?

Accepted Answer

They form seals that block the passage of fluids between cells.

Question 17

A cell is exposed to a toxin that specifically disrupts the function of its gap junctions. Which of the following processes would be most directly affected?

Accepted Answer

Cell-cell communication via direct transfer of ions and small molecules

Question 18

Which of the following best explains why some membrane proteins are immobile within the lipid bilayer?

Accepted Answer

They are anchored to protein complexes or the cytoskeleton.

Question 19

Which of the following is a correct statement about the movement of phospholipids in the membrane?

Accepted Answer

Phospholipids can move laterally within the same monolayer.

Cell Membranes: Structure, Function, and Chemistry (Becker’s World of the Cell, Chapter 7)

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