Q: Which equation correctly represents the calculation of membrane potential ($$V_m) $$using the Nernst equation for a monovalent ion?

$$V_m = \frac{RT}{zF} \ln \left( \frac{[\text{ion}]_{\text{outside}}}{[\text{ion}]_{\text{inside}}} \right)$$

Question 1

Which of the following best describes the fluid mosaic model of biological membranes?

Accepted Answer

A double layer of phospholipids with proteins and carbohydrates embedded and moving laterally.

Question 2

Which property of phospholipids is most responsible for the formation of the bilayer structure in cell membranes?

Accepted Answer

Their amphipathic nature, having both hydrophilic and hydrophobic regions.

Question 3

A researcher observes that a cell membrane becomes more rigid at lower temperatures. Which change in membrane composition would most likely counteract this effect?

Accepted Answer

Increasing the proportion of unsaturated fatty acids.

Question 4

Which of the following is NOT a function of membrane proteins?

Accepted Answer

Energy storage

Question 5

A red blood cell is placed in a solution and swells until it bursts. Which term best describes the solution?

Accepted Answer

Hypotonic

Question 6

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It involves transport proteins that help specific molecules cross the membrane.

Question 7

Which equation correctly represents the calculation of membrane potential ($$V_m) $$using the Nernst equation for a monovalent ion?

Accepted Answer

$$V_m = \frac{RT}{zF} \ln \left( \frac{[	ext{ion}]_{	ext{outside}}}{[	ext{ion}]_{	ext{inside}}} ight)$$

Question 8

Which of the following best explains why hydrophobic molecules can cross the cell membrane more easily than hydrophilic molecules?

Accepted Answer

Hydrophobic molecules dissolve in the lipid bilayer due to their nonpolar nature.

Question 9

A plant cell is placed in a hypertonic solution. What is the most likely outcome?

Accepted Answer

The cell will lose water and undergo plasmolysis.

Question 10

Which of the following is an example of active transport?

Accepted Answer

Pumping sodium ions out of a cell using the sodium-potassium pump.

Question 11

Which two forces combine to produce the electrochemical gradient across a membrane?

Accepted Answer

Electrical potential and chemical concentration gradient

Question 12

Which of the following is a primary electrogenic pump in animal cells?

Accepted Answer

Sodium-potassium pump

Question 13

A patient is diagnosed with a genetic defect in aquaporin proteins. Which physiological process is most likely to be directly affected?

Accepted Answer

Facilitated diffusion of water across cell membranes

Question 14

Which process involves the engulfment of large particles by the cell membrane to form an internal vesicle?

Accepted Answer

Phagocytosis

Question 15

A cell uses receptor-mediated endocytosis to import cholesterol. Which step is unique to this process compared to other forms of endocytosis?

Accepted Answer

Binding of specific ligands to cell-surface receptors before vesicle formation

Question 16

Which of the following best describes cotransport?

Accepted Answer

The coupling of the downhill diffusion of one substance to the uphill transport of another.

Question 17

A cell is placed in an isotonic solution. Which of the following best describes the net movement of water?

Accepted Answer

There is no net movement of water across the membrane.

Question 18

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

Accepted Answer

A cell membrane allows glucose to enter via a specific carrier protein but blocks sodium ions unless a channel is open.

Question 19

Which of the following best explains why plant cells do not burst when placed in a hypotonic solution, while animal cells do?

Accepted Answer

Plant cells have a rigid cell wall that provides structural support.

Question 20

A scientist is studying the movement of potassium ions ($$K^+) $$across a cell membrane. If the concentration of $$K^+ is $$higher inside the cell than outside, but the inside of the cell is negatively charged, what will determine the direction of $$K^+$$ movement?

Accepted Answer

Both the concentration gradient and the electrical gradient (the electrochemical gradient) will determine movement.

Transport Across Membranes: Structure, Function, and Mechanisms

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