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 will happen to the cell, and why?

Accepted Answer

It will swell and possibly lyse because water moves into the cell by osmosis.

Question 3

Which equation describes the rate of facilitated diffusion by a carrier protein, and what do the terms represent?

Accepted Answer

$$v = V_{max} [S] / (K_m + [S])$$, where $$V_{max} is $$maximum velocity, $$K_m is $$the Michaelis constant, and $$[S] is $$substrate concentration.

Question 4

Which of the following is an example of primary active transport?

Accepted Answer

Na+/K+ ATPase pumping sodium and potassium ions across the plasma membrane

Question 5

A patient with cystic fibrosis has a mutation in the CFTR protein. What is the primary cellular consequence of this mutation?

Accepted Answer

Reduced chloride ion transport across epithelial cell membranes

Question 6

Which of the following statements about osmosis is correct?

Accepted Answer

Water moves from a region of lower solute concentration to higher solute concentration.

Question 7

Which Nobel Prize-winning discovery is correctly matched with its scientist?

Accepted Answer

Discovery of aquaporins – Peter Agre

Question 8

Which of the following best explains why facilitated diffusion exhibits saturation kinetics?

Accepted Answer

Carrier proteins have a finite number and each can only transport a limited number of solute molecules at a time.

Question 9

Which of the following is a correct example of secondary active transport in animal cells?

Accepted Answer

Sodium-glucose symporter using the sodium gradient to drive glucose uptake

Question 10

Which of the following statements about the Na+/K+ ATPase is TRUE?

Accepted Answer

It is a P-type ATPase that is reversibly phosphorylated during its cycle.

Question 11

A scientist is studying a membrane protein that allows rapid passage of water but not ions or other solutes. Which protein is she most likely studying?

Accepted Answer

Aquaporin

Question 12

Which of the following best describes the movement of ions through an ion channel?

Accepted Answer

Ions move down their electrochemical gradient through a hydrophilic pore.

Question 13

Which of the following is a property of ABC-type ATPases?

Accepted Answer

They have two hydrophobic membrane domains and two peripheral ATP-binding domains.

Question 14

A cell is placed in a hypertonic solution. What is the expected outcome?

Accepted Answer

The cell will shrink as water leaves.

Question 15

Which of the following best describes the function of the GLUT1 transporter in erythrocytes?

Accepted Answer

It is a uniporter that facilitates glucose movement down its concentration gradient.

Question 16

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

Accepted Answer

Carrier proteins bind solutes and undergo conformational changes, while channel proteins form open pores.

Question 17

Which of the following is a real-world example of indirect active transport in plants?

Accepted Answer

Proton gradients established by V-type ATPases drive the uptake of sugars via symporters.

Question 18

Which of the following best explains why the rate of simple diffusion increases linearly with the concentration gradient?

Accepted Answer

Simple diffusion does not require a protein and is not saturable.

Question 19

Which of the following is a function of the anion exchange protein in erythrocytes?

Accepted Answer

It exchanges chloride and bicarbonate ions in a 1:1 ratio.

Question 20

Which of the following best describes the effect of competitive inhibition on carrier-mediated transport?

Accepted Answer

A structurally similar molecule competes with the substrate for binding to the carrier protein, reducing transport rate.

Transport Across Membranes: Overcoming the Permeability Barrier

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