Question 1

Which statement best describes the fluid mosaic model of the cell membrane?

Accepted Answer

The membrane is a dynamic structure with various proteins and lipids that move laterally within the bilayer.

Question 2

Which property of phospholipids is most responsible for the formation of the lipid bilayer in cell membranes?

Accepted Answer

Their amphipathic nature, with hydrophilic heads and hydrophobic tails.

Question 3

A cell is placed in a solution and begins to swell until it bursts. What type of solution is the cell in, and why does this occur?

Accepted Answer

Hypotonic; water enters the cell due to a lower solute concentration outside.

Question 4

Which of the following best explains why cholesterol acts as a buffer for membrane fluidity?

Accepted Answer

Cholesterol restricts movement of phospholipids at high temperatures and prevents close packing at low temperatures.

Question 5

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

Accepted Answer

O$$_2$$

Question 6

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

Accepted Answer

Cells will gain water, swell, and may burst (lyse).

Question 7

Which function is NOT typically associated with membrane proteins?

Accepted Answer

Structural support for the cell wall

Question 8

What is the main difference between simple diffusion and facilitated diffusion?

Accepted Answer

Facilitated diffusion uses membrane proteins to move molecules down their concentration gradient.

Question 9

Which equation correctly represents the calculation of osmolarity for a solution containing 0.1 M NaCl and 0.1 M glucose?

Accepted Answer

$$0.3\ 	ext{Osm/L}$$

Question 10

A plant cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

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

Question 11

Which of the following best describes secondary active transport?

Accepted Answer

It relies on the energy stored in an ion gradient created by primary active transport.

Question 12

Which of the following is a real-world example of osmoregulation in unicellular eukaryotes?

Accepted Answer

Using contractile vacuoles to pump excess water out in freshwater environments.

Question 13

Which of the following statements about transmembrane proteins is correct?

Accepted Answer

They span the lipid bilayer and often contain nonpolar regions that interact with the hydrophobic core.

Question 14

Why are individuals lacking the CCR5 protein on their immune cells resistant to HIV infection?

Accepted Answer

CCR5 is required for HIV to bind and enter the cell along with CD4.

Question 15

Which of the following best describes the movement of water during osmosis?

Accepted Answer

Water moves from an area of low solute concentration to high solute concentration across a semipermeable membrane.

Question 16

Which of the following is NOT a function of glycoproteins in the plasma membrane?

Accepted Answer

Forming tight junctions between adjacent cells

Question 17

A solution contains 0.2 M NaCl and 0.1 M glucose. What is the total osmolarity of the solution?

Accepted Answer

$$0.5\ 	ext{Osm/L}$$

Question 18

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Membrane fluidity increases with more unsaturated fatty acid tails due to kinks that prevent tight packing.

Question 19

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

Accepted Answer

Active transport

Question 20

A marine fish is transferred from seawater (isotonic to its cells) to freshwater (hypotonic). What is the most likely effect on its cells?

Accepted Answer

Cells will gain water, swell, and may burst.

Membrane Structure and Dynamics: Concepts 7.1–7.4

Study Guide - Practice Questions