Question 1

Which of the following molecules is most likely to cross a pure phospholipid bilayer by simple diffusion without the aid of a protein transporter?

Accepted Answer

Oxygen (O2)

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

Hypotonic

Question 3

Which of the following statements about facilitated diffusion is CORRECT?

Accepted Answer

It can become saturated at high solute concentrations.

Question 4

A patient is given a drug that structurally resembles glucose and binds to the GLUT1 transporter, reducing glucose uptake into cells. What type of inhibition is this?

Accepted Answer

Competitive inhibition

Question 5

Which of the following best explains why ions such as Na+ and K+ require protein transporters to cross the plasma membrane?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the membrane.

Question 6

Which of the following is a function of active transport in cells?

Accepted Answer

Establishing nonequilibrium concentrations of ions across membranes

Question 7

The Na+/K+ ATPase pump moves sodium and potassium ions across the plasma membrane. Which statement is TRUE regarding this process?

Accepted Answer

It requires energy from ATP hydrolysis.

Question 8

Which of the following best describes the movement of water across a selectively permeable membrane in response to solute concentration differences?

Accepted Answer

Osmosis

Question 9

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

Accepted Answer

The plasma membrane will pull away from the cell wall (plasmolysis).

Question 10

Which of the following is a distinguishing feature of carrier proteins compared to channel proteins?

Accepted Answer

Carrier proteins undergo conformational changes to transport solutes.

Question 11

Which of the following is an example of indirect (secondary) active transport?

Accepted Answer

Na+/glucose symporter

Question 12

Which of the following best describes the electrochemical potential for an ion?

Accepted Answer

It is the sum of the concentration gradient and the charge gradient across the membrane.

Question 13

Which of the following is TRUE about aquaporins?

Accepted Answer

They allow rapid passage of water molecules.

Question 14

A cell lacking functional ABC-type ATPases would likely show which of the following phenotypes?

Accepted Answer

Increased sensitivity to antibiotics

Question 15

Which of the following best describes the process of symport?

Accepted Answer

Two solutes are transported simultaneously in the same direction.

Question 16

Which of the following would most likely INCREASE the rate of glucose transport into a cell via GLUT1 in the presence of a competitive inhibitor?

Accepted Answer

Increasing the glucose concentration outside the cell

Question 17

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

Accepted Answer

Movement of small nonpolar molecules without protein assistance

Question 18

Which of the following best explains why water diffuses more rapidly across membranes than expected for a polar molecule?

Accepted Answer

Membranes contain aquaporins that facilitate water movement.

Question 19

Which of the following is TRUE regarding the directionality of active transport?

Accepted Answer

It has intrinsic directionality, moving solutes in a specific direction.

Question 20

Which of the following is a consequence of a defect in the CFTR chloride channel in humans?

Accepted Answer

Cystic fibrosis due to improper Cl– transport in the lungs

Transport Across Membranes: Overcoming the Permeability Barrier (Cell Biology Study Guide)

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