$$[\text{Water}] \propto \frac{1}{[\text{Solute}]}$$

Question 1

Which of the following best describes the structure of the plasma membrane according to the fluid mosaic model?

Accepted Answer

A double layer of phospholipids with proteins and carbohydrates scattered throughout, allowing for flexibility and movement.

Question 2

A red blood cell is placed in a solution containing 0.1% NaCl. Normal saline (isotonic to RBCs) is 0.9% NaCl. What will happen to the RBC, and why?

Accepted Answer

The cell will swell and possibly lyse because water will move into the cell due to the hypotonic solution.

Question 3

Which of the following is a function of integral membrane proteins?

Accepted Answer

Acting as transport channels, receptors, and enzymes within the membrane.

Question 4

Which equation correctly represents the relationship between solute concentration and water concentration in osmosis?

Accepted Answer

$$[	ext{Water}] \propto \frac{1}{[	ext{Solute}]}$$

Question 5

Which type of cell junction would be most important in the lining of the stomach to prevent acid from leaking between cells?

Accepted Answer

Tight junctions

Question 6

Which of the following best explains why the inside of a resting cell membrane is more negative than the outside?

Accepted Answer

K+ leaks out of the cell more easily than Na+ enters, and negatively charged proteins remain inside.

Question 7

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

Accepted Answer

Glucose being transported into a cell along with Na+ down the Na+ gradient established by the Na+-K+ pump.

Question 8

A patient receives an intravenous solution that is hypertonic compared to their red blood cells. What is the most likely effect on the RBCs?

Accepted Answer

They will shrink due to water leaving the cells.

Question 9

Which of the following best describes the role of cholesterol in the plasma membrane?

Accepted Answer

It increases membrane stability and fluidity.

Question 10

Which of the following is true regarding facilitated diffusion?

Accepted Answer

It uses carrier or channel proteins to move substances down their concentration gradient.

Question 11

Which of the following best describes the function of the glycocalyx?

Accepted Answer

It provides specific biological markers for cell-to-cell recognition.

Question 12

Which of the following is a correct statement about the sodium-potassium pump (Na+/K+ ATPase)?

Accepted Answer

It moves 3 Na+ ions out of the cell and 2 K+ ions into the cell per ATP hydrolyzed.

Question 13

Which of the following best explains why water moves into a cell placed in a hypotonic solution?

Accepted Answer

The solute concentration is higher inside the cell, so water moves in to balance the concentration.

Question 14

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

Accepted Answer

Storing genetic information.

Question 15

Which of the following best describes the movement of K+ and Na+ during the establishment of the resting membrane potential?

Accepted Answer

K+ moves out of the cell and Na+ moves into the cell, both down their concentration gradients.

Question 16

Which of the following is a property of gap junctions?

Accepted Answer

They allow the passage of ions and small molecules between adjacent cells.

Question 17

Which of the following is true about passive transport across the plasma membrane?

Accepted Answer

It moves substances down their concentration gradient.

Question 18

Which of the following best describes the effect of a hypertonic solution on a red blood cell?

Accepted Answer

Water leaves the cell, causing it to shrink (crenate).

Question 19

Which of the following is a correct example of carrier-mediated facilitated diffusion?

Accepted Answer

Glucose entering a cell via a specific protein carrier.

Question 20

Which of the following best explains why the Na+-K+ pump is considered an antiporter?

Accepted Answer

It moves Na+ out of the cell and K+ into the cell, in opposite directions.

The Cellular Level of Organization: Structure and Function of the Plasma Membrane

Study Guide - Practice Questions