Question 1

Which of the following best describes the structure of a biological membrane according to the fluid mosaic model?

Accepted Answer

A double layer of phospholipids with proteins and carbohydrates embedded and able to move laterally.

Question 2

Which of the following changes would most likely increase the fluidity of a cell membrane at low temperatures?

Accepted Answer

Increasing the proportion of unsaturated fatty acids in phospholipids.

Question 3

A scientist observes that a certain molecule can cross the cell membrane without the use of energy, but only when a specific protein is present. Which transport process is most likely responsible?

Accepted Answer

Facilitated diffusion

Question 4

Which equation correctly represents the calculation of osmotic pressure ($$\Pi) $$across a membrane?

Accepted Answer

$$\Pi = cRT$$

Question 5

A red blood cell is placed in a hypotonic solution. What is the most likely outcome, and why?

Accepted Answer

The cell will swell and may burst because water moves in by osmosis.

Question 6

Which of the following best explains why cholesterol is important in animal cell membranes?

Accepted Answer

It modulates membrane fluidity by interacting with phospholipid fatty acid tails.

Question 7

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral membrane proteins are at least partly embedded in the phospholipid bilayer.

Question 8

A cell is placed in a solution with a higher solute concentration than its cytoplasm. Which term best describes the solution, and what will happen to the cell?

Accepted Answer

Hypertonic; the cell will shrink.

Question 9

Which of the following molecules is most likely to cross a pure phospholipid bilayer by simple diffusion?

Accepted Answer

O$$_2$$

Question 10

Which factor would NOT increase the rate of diffusion of a solute across a membrane?

Accepted Answer

Decreasing the concentration gradient across the membrane

Question 11

A cell uses ATP to move sodium ions out of the cell against their concentration gradient. Which type of transport is this an example of?

Accepted Answer

Active transport

Question 12

Which of the following best describes the role of glycoproteins in the cell membrane?

Accepted Answer

They are involved in cell recognition and communication.

Question 13

If a cell membrane becomes less fluid at lower temperatures, which of the following changes would help maintain membrane fluidity?

Accepted Answer

Increasing the proportion of unsaturated fatty acids.

Question 14

Which of the following is a property of transmembrane proteins?

Accepted Answer

They extend through the bilayer and may have domains on both sides of the membrane.

Question 15

Which of the following best explains why polar molecules such as glucose require facilitated diffusion to cross the cell membrane?

Accepted Answer

They are repelled by the hydrophobic interior of the lipid bilayer.

Question 16

A researcher observes that at higher temperatures, the percentage of mobile proteins in a membrane increases. Which property of membranes does this observation illustrate?

Accepted Answer

Membrane fluidity increases with temperature.

Question 17

Which of the following statements about osmosis is correct?

Accepted Answer

Osmosis is the diffusion of water across a selectively permeable membrane.

Question 18

A cell is placed in an isotonic solution. What will happen to the cell's volume over time?

Accepted Answer

It will remain the same because there is no net movement of water.

Question 19

Which of the following best describes the function of proteoglycans in the cell membrane?

Accepted Answer

They are involved in cell-cell recognition and communication.

Question 20

Which of the following is an example of secondary active transport?

Accepted Answer

Movement of glucose into a cell using the energy from sodium ion movement down its gradient.

Cell Membranes & Transport: Structure, Function, and Mechanisms

Guida di studio - Domande di pratica

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