Question 1

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

Accepted Answer

A flexible bilayer of phospholipids with embedded proteins that move freely, creating a constantly changing pattern.

Question 2

A red blood cell is placed in a solution and begins to shrink. Which of the following best describes the tonicity of the solution and the process occurring?

Accepted Answer

The solution is hypertonic, and water is leaving the cell by osmosis.

Question 3

Which of the following is a function of the glycocalyx on the plasma membrane?

Accepted Answer

Acting as a biological marker for cell-to-cell recognition.

Question 4

Which type of cell junction would you expect to find in tissues that experience significant mechanical stress, such as cardiac muscle?

Accepted Answer

Desmosomes

Question 5

A solution contains 1 M NaCl. What is its osmolarity?

Accepted Answer

$$2~	ext{osmol/L}$$

Question 6

Which of the following best explains why oxygen can diffuse directly through the plasma membrane?

Accepted Answer

Oxygen is a small, nonpolar molecule.

Question 7

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

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

Question 8

A patient receives an intravenous solution that is hypotonic relative to their red blood cells. What is the most likely outcome for the cells?

Accepted Answer

The cells will swell and may burst due to water gain.

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 osmosis?

Accepted Answer

Water moves from areas of low solute concentration to high solute concentration.

Question 11

A cell is placed in a solution and neither swells nor shrinks. Which of the following best describes the solution?

Accepted Answer

Isotonic

Question 12

Which of the following is a function of peripheral proteins in the plasma membrane?

Accepted Answer

Acting as enzymes or motor proteins for cell shape changes

Question 13

Which of the following best explains why burn patients are at risk for dehydration?

Accepted Answer

Damaged plasma membranes allow free diffusion of fluids and ions out of cells.

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 glucose into a cell via carrier-mediated facilitated diffusion?

Accepted Answer

Glucose binds to a specific carrier protein, which changes shape to transport it down its concentration gradient.

Question 16

Which of the following cell junctions allows for the rapid passage of ions and electrical signals between cardiac muscle cells?

Accepted Answer

Gap junctions

Question 17

Which of the following factors would increase the rate of diffusion across a plasma membrane?

Accepted Answer

Increasing the concentration gradient

Question 18

Which of the following best explains why plant cells do not burst when placed in a hypotonic solution, but animal cells do?

Accepted Answer

Plant cells have a rigid cell wall that limits hydrostatic pressure.

Question 19

Which of the following is true regarding the structure of phospholipids in the plasma membrane?

Accepted Answer

The fatty acid tails are hydrophobic and face each other inside the bilayer.

Question 20

Which of the following best describes the effect of a hypertonic intravenous solution on a patient’s red blood cells?

Accepted Answer

Cells will shrink due to water efflux.

Cells: The Living Units – Structure and Function of the Plasma Membrane

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