Question 1

Which of the following best describes the difference between simple diffusion and facilitated diffusion across a biological membrane?

Accepted Answer

Facilitated diffusion requires a specific membrane protein, while simple diffusion does not.

Question 2

A red blood cell is placed in a hypotonic solution. What is the most likely outcome, and why?

Accepted Answer

The cell will swell and may burst because water will move into the cell.

Question 3

Which of the following equations correctly represents the rate of simple diffusion across a membrane?

Accepted Answer

$$v_{inward} = P \Delta [S]$$

Question 4

Which of the following is a key feature of active transport, but not passive transport?

Accepted Answer

Requirement for metabolic energy input

Question 5

A plant cell is placed in a hypertonic solution. What process occurs, and what is the result?

Accepted Answer

Plasmolysis; the plasma membrane pulls away from the cell wall

Question 6

Which of the following statements about the GLUT1 transporter is correct?

Accepted Answer

GLUT1 is a uniport carrier that facilitates glucose movement down its concentration gradient.

Question 7

Which of the following best explains why the rate of facilitated diffusion plateaus at high substrate concentrations?

Accepted Answer

The transport proteins become saturated and cannot increase their rate further.

Question 8

Which of the following is true regarding the movement of ions across membranes?

Accepted Answer

Ion movement is determined by both the concentration gradient and the membrane potential (electrochemical gradient).

Question 9

Which of the following is a function of the CFTR protein in airway epithelial cells?

Accepted Answer

Regulates chloride ion passage, affecting water movement and mucus hydration

Question 10

Which of the following best describes the difference between a symport and an antiport carrier protein?

Accepted Answer

Symport moves two solutes in the same direction; antiport moves two solutes in opposite directions.

Question 11

Which of the following is NOT a property of simple diffusion?

Accepted Answer

Requires a membrane protein

Question 12

Which of the following best explains why water moves from chamber A to chamber B in osmosis, as shown in the diagram?

Accepted Answer

Water moves toward the region of higher solute concentration.

Question 13

Which of the following is a property of porins but NOT of ion channels?

Accepted Answer

Form large, less specific pores for solute passage

Question 14

Which of the following is true about aquaporins?

Accepted Answer

They allow rapid passage of water molecules across membranes.

Question 15

A patient with cystic fibrosis has a mutation in the CFTR gene. Which of the following cellular processes is most directly affected?

Accepted Answer

Regulation of chloride ion and water movement in airway cells

Question 16

Which of the following is a characteristic of carrier proteins involved in facilitated diffusion?

Accepted Answer

They undergo conformational changes to transport solutes.

Question 17

Which of the following best describes the movement of oxygen (O2) across the erythrocyte membrane?

Accepted Answer

Simple diffusion down its concentration gradient

Question 18

Which of the following is true about the erythrocyte anion exchange protein?

Accepted Answer

It is an antiport carrier that exchanges Cl– and HCO3– in a 1:1 ratio.

Question 19

Which of the following factors does NOT affect the permeability coefficient (P) in the rate equation for simple diffusion?

Accepted Answer

Concentration gradient of the solute

Question 20

Which of the following processes is most likely to be inhibited by a competitive inhibitor?

Accepted Answer

Facilitated diffusion via a carrier protein

Transport Across Membranes: Overcoming the Permeability Barrier

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