Question 1

Which of the following best explains why membranes rich in unsaturated fatty acids remain more fluid at lower temperatures than those rich in saturated fatty acids?

Accepted Answer

Unsaturated fatty acids have kinks in their hydrocarbon tails, preventing tight packing of phospholipids.

Question 2

A red blood cell is placed in a solution and swells until it bursts. Which of the following best describes the tonicity of the solution relative to the cell?

Accepted Answer

The solution is hypotonic to the cell.

Question 3

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It uses energy from ATP hydrolysis to move $$3$$ sodium ions out of the cell and $$2$$ potassium ions into the cell.

Question 4

Which of the following best describes the function of aquaporins in the plasma membrane?

Accepted Answer

They facilitate the rapid diffusion of water molecules across the membrane.

Question 5

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

Accepted Answer

The cell will lose water, and the plasma membrane will pull away from the cell wall (plasmolysis).

Question 6

Which of the following is a function of membrane carbohydrates?

Accepted Answer

They serve as markers for cell recognition.

Question 7

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

It is a form of endocytosis in which specific molecules bind to receptors on the cell surface, triggering vesicle formation.

Question 8

Which of the following molecules would most easily diffuse through a pure phospholipid bilayer without the aid of a transport protein?

Accepted Answer

Oxygen ($$O_2)$$

Question 9

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It requires transport proteins but does not require energy from ATP.

Question 10

A patient with familial hypercholesterolemia has high levels of cholesterol in the blood because:

Accepted Answer

Their cells lack functional LDL receptor proteins, preventing uptake of cholesterol by receptor-mediated endocytosis.

Question 11

Which of the following best describes cotransport in plant cells?

Accepted Answer

The downhill diffusion of $$H^+ is $$coupled to the active transport of sucrose into the cell.

Question 12

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

Accepted Answer

Synthesis of phospholipids

Question 13

Which of the following best explains why cholesterol acts as a 'fluidity buffer' in animal cell membranes?

Accepted Answer

At high temperatures, cholesterol restrains phospholipid movement; at low temperatures, it prevents tight packing.

Question 14

Which of the following scenarios best illustrates the concept of selective permeability?

Accepted Answer

Oxygen diffuses rapidly through the membrane, while glucose requires a transport protein.

Question 15

A nerve cell responds to an electrical stimulus by opening potassium ion channels. This is an example of:

Accepted Answer

A gated channel protein responding to a stimulus.

Question 16

Which of the following equations best represents the movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$$	ext{Water moves from a region of lower solute concentration to a region of higher solute concentration}$$

Question 17

Which of the following is true about the sidedness (asymmetry) of biological membranes?

Accepted Answer

The composition and distribution of proteins, lipids, and carbohydrates are different on the two sides of the membrane.

Question 18

Which of the following best describes the role of the electrochemical gradient in ion transport?

Accepted Answer

It combines the chemical concentration gradient and the electrical potential across the membrane to drive ion diffusion.

Question 19

Which of the following is an example of bulk transport across the plasma membrane?

Accepted Answer

A pancreatic cell secreting insulin via exocytosis.

Question 20

Which of the following would most likely occur if a freshwater Paramecium's contractile vacuole stopped functioning?

Accepted Answer

The cell would swell and possibly burst due to excess water intake.

Membrane Structure and Function: Study Notes

Study Guide - Practice Questions

Study Guide - Flashcards