Question 1

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

Accepted Answer

A dynamic structure where proteins bob in a fluid bilayer of phospholipids, with both lipids and proteins able to move laterally.

Question 2

What is the primary reason that membranes rich in unsaturated fatty acids remain more fluid at lower temperatures?

Accepted Answer

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

Question 3

Cholesterol plays a key role in animal cell membranes. Which statement best describes its function?

Accepted Answer

Cholesterol decreases membrane fluidity at high temperatures and prevents solidification at low temperatures.

Question 4

A freshwater Paramecium lives in a hypotonic environment. Which adaptation allows it to survive without bursting?

Accepted Answer

It uses a contractile vacuole to expel excess water.

Question 5

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

Accepted Answer

Oxygen ($$O_2)$$

Question 6

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

Accepted Answer

Hypotonic

Question 7

Which process requires energy input from ATP to move substances across the plasma membrane?

Accepted Answer

Active transport

Question 8

The sodium-potassium pump is an example of which type of membrane transport?

Accepted Answer

Active transport

Question 9

Which of the following best explains why plant cells become turgid in a hypotonic solution?

Accepted Answer

Water enters the cell, and the cell wall exerts turgor pressure to prevent bursting.

Question 10

Which of the following is a function of membrane proteins?

Accepted Answer

Facilitating cell-cell recognition

Question 11

A patient with familial hypercholesterolemia has high blood cholesterol because:

Accepted Answer

Their cells have defective LDL receptor proteins, preventing cholesterol uptake by receptor-mediated endocytosis.

Question 12

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It uses transport proteins to move substances down their concentration gradient.

Question 13

Which type of transport protein is responsible for the rapid movement of water across cell membranes?

Accepted Answer

Aquaporin

Question 14

A plant cell is placed in a hypertonic solution. What will most likely happen?

Accepted Answer

The cell will undergo plasmolysis as the membrane pulls away from the cell wall.

Question 15

Which of the following best describes cotransport in the context of membrane transport?

Accepted Answer

The active transport of one solute directly coupled to the passive transport of another solute down its gradient.

Question 16

Which of the following is NOT a type of endocytosis?

Accepted Answer

Exocytosis

Question 17

Which of the following statements about the permeability of the lipid bilayer is correct?

Accepted Answer

Ions and large polar molecules require transport proteins to cross the membrane efficiently.

Question 18

Which of the following best explains why glucose carrier proteins do not transport fructose?

Accepted Answer

Carrier proteins are specific to the shape of the molecule they transport.

Question 19

Which of the following is a real-world example of bulk transport via exocytosis?

Accepted Answer

The secretion of insulin by pancreatic cells.

Question 20

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

Accepted Answer

Facilitated diffusion through gated channels.

Membrane Structure and Function: Study Notes for General Biology

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