Question 1

Which property of the phospholipid bilayer is most critical for the selective permeability of the plasma membrane?

Accepted Answer

Its hydrophobic core that restricts passage of polar and charged molecules

Question 2

A red blood cell is placed in a solution and begins to swell and eventually bursts. What type of solution is the cell in?

Accepted Answer

Hypotonic solution

Question 3

Which of the following best describes simple diffusion across the plasma membrane?

Accepted Answer

Movement of nonpolar molecules directly through the phospholipid bilayer without the use of membrane proteins

Question 4

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

It requires membrane proteins to transport charged or polar solutes

Question 5

Which equation best represents the relationship between osmotic pressure ($\Pi$), solute concentration ($C$), gas constant ($R$), and temperature ($T$) in a solution?

Accepted Answer

$\Pi = CRT$

Question 6

During vigorous exercise, the extracellular fluid (ECF) becomes hypertonic. What is the physiological consequence for muscle cells?

Accepted Answer

Water moves out of the cells, causing them to shrink (crenate)

Question 7

Which of the following is NOT a variable that determines whether a substance crosses the plasma membrane by passive or active transport?

Accepted Answer

Number of mitochondria in the cell

Question 8

The sodium-potassium pump (Na+/K+ ATPase) moves ions against their concentration gradients. For each ATP molecule hydrolyzed, what is the net movement of Na+ and K+ ions?

Accepted Answer

3 Na+ out, 2 K+ in

Question 9

Which of the following best describes secondary active transport?

Accepted Answer

It uses the energy stored in the gradient of one substance to move another substance against its gradient

Question 10

A patient is given an intravenous solution that is hypertonic compared to their cytosol. What is the expected effect on their red blood cells?

Accepted Answer

Cells will shrink due to water loss

Question 11

Which of the following transport mechanisms is most likely responsible for the movement of glucose into intestinal epithelial cells?

Accepted Answer

Secondary active transport (Na+-glucose symporter)

Question 12

What is the main driving force for passive transport across the plasma membrane?

Accepted Answer

Concentration gradient

Question 13

Which of the following statements about membrane potential is correct?

Accepted Answer

It is created by a separation of charges across the plasma membrane

Question 14

Which process requires energy from ATP and is used to move large polar macromolecules across the plasma membrane?

Accepted Answer

Vesicular transport (exocytosis/endocytosis)

Question 15

A cell is placed in an isotonic solution. What will happen to the cell's volume?

Accepted Answer

It will remain unchanged

Question 16

Which of the following is an example of antiport secondary active transport?

Accepted Answer

Ca2+ antiporter in cardiomyocytes

Question 17

Which equation best describes the movement of solute molecules during diffusion?

Accepted Answer

$J = -D \frac{dC}{dx}$

Question 18

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the movement of water molecules from low solute concentration to high solute concentration

Question 19

Which of the following best explains why sports drinks are mildly hypotonic to cells after exercise?

Accepted Answer

They contain fewer solutes than the cytosol, causing water to enter the cells and restore normal cytosol concentration

Question 20

Which of the following is NOT a form of passive transport?

Accepted Answer

Primary active transport

Transport Across the Plasma Membrane

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