Question 1

Which of the following best describes the role of peripheral proteins in the plasma membrane?

Accepted Answer

They are associated with only one side of the membrane and often function in cell signaling or attachment.

Question 2

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

Accepted Answer

Water will move out of the cell, causing it to shrink.

Question 3

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Cholesterol within the membrane acts as a fluidity buffer, reducing fluidity at high temperatures and increasing it at low temperatures.

Question 4

Which equation best represents the rate of diffusion of small, nonpolar molecules across a membrane?

Accepted Answer

$J = -D \frac{dC}{dx}$

Question 5

A red blood cell is placed in pure water. What type of solution is this, and what is the expected outcome?

Accepted Answer

Hypotonic; the cell will swell and may burst.

Question 6

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

Accepted Answer

Synthesis of DNA

Question 7

Facilitated diffusion differs from simple diffusion in that:

Accepted Answer

Facilitated diffusion uses membrane proteins to transport substances down their concentration gradient.

Question 8

Which of the following best explains why unsaturated fatty acids increase membrane fluidity?

Accepted Answer

Their double bonds create kinks, preventing tight packing of phospholipids.

Question 9

Which process is responsible for the movement of water across a semipermeable membrane from an area of low solute concentration to high solute concentration?

Accepted Answer

Osmosis

Question 10

A cell uses a sodium-potassium pump to maintain ion gradients. Which type of transport is this?

Accepted Answer

Active transport

Question 11

Which of the following statements about endocytosis is correct?

Accepted Answer

It involves the cell engulfing material by forming a vesicle from the plasma membrane.

Question 12

If a cell is placed in a solution with a lower water concentration than inside the cell, what type of solution is this and what will happen?

Accepted Answer

Hypertonic; water will leave the cell.

Question 13

Which of the following is a correct statement about facilitated diffusion?

Accepted Answer

It requires carrier or channel proteins.

Question 14

Which equation best describes the relationship between water movement and solute concentration during osmosis?

Accepted Answer

$\Delta \Psi = \Psi_s + \Psi_p$

Question 15

Which of the following is an example of bulk transport?

Accepted Answer

Endocytosis

Question 16

A cell is exposed to a toxin that blocks ATP production. Which transport process will be most directly affected?

Accepted Answer

Active transport

Question 17

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

Accepted Answer

A dynamic structure with proteins and lipids that move laterally within the bilayer.

Question 18

Which of the following is true about isotonic solutions?

Accepted Answer

There is no net movement of water across the membrane.

Question 19

Which process requires membrane proteins to move substances against their concentration gradient using energy?

Accepted Answer

Active transport

Question 20

Which of the following is a correct statement about the movement of charged particles across the membrane?

Accepted Answer

It is driven by both the concentration gradient and the electrical gradient (membrane potential).

Cell Membrane Structure and Transport Mechanisms

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