Question 1

Which of the following best describes the structure and function of the plasma membrane according to the fluid mosaic model?

Accepted Answer

It is a dynamic structure where proteins float in or on a fluid bilayer of phospholipids, allowing lateral movement.

Question 2

Which of the following molecules would most easily diffuse through a plasma membrane without the help of a transport protein?

Accepted Answer

Oxygen (O\_2)

Question 3

What is the primary function of cholesterol in animal cell membranes at normal body temperature (37°C)?

Accepted Answer

It restrains the movement of phospholipids, reducing membrane fluidity.

Question 4

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

Accepted Answer

It will take up water, become turgid, and maintain its healthy state.

Question 5

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

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

Question 6

Which process is responsible for the uptake of specific macromolecules into the cell via receptor proteins?

Accepted Answer

Receptor-mediated endocytosis

Question 7

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

Accepted Answer

The cell will lose water and shrink.

Question 8

Which of the following best explains why ions such as Na\^+ and K\^+ cannot easily cross the plasma membrane without assistance?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the membrane.

Question 9

Which of the following is a function of glycoproteins in the plasma membrane?

Accepted Answer

Acting as markers for cell identification

Question 10

Which of the following best describes the movement of water across a selectively permeable membrane?

Accepted Answer

Facilitated diffusion through aquaporins

Question 11

What is the main difference between channel proteins and carrier proteins in facilitated diffusion?

Accepted Answer

Channel proteins provide a hydrophilic tunnel, while carrier proteins undergo a shape change to move the solute.

Question 12

Which of the following best describes the sodium-potassium pump?

Accepted Answer

It uses ATP to move Na\^+ out of the cell and K\^+ into the cell against their concentration gradients.

Question 13

Which of the following is true about the effect of unsaturated fatty acids on membrane fluidity?

Accepted Answer

They increase membrane fluidity, especially at lower temperatures.

Question 14

Which of the following best describes exocytosis?

Accepted Answer

Transport vesicles fuse with the plasma membrane to release contents outside the cell.

Question 15

A cell is placed in an isotonic solution. What will happen to the cell?

Accepted Answer

There will be no net movement of water across the membrane.

Question 16

Which of the following is a characteristic of integral membrane proteins?

Accepted Answer

They penetrate the hydrophobic core of the lipid bilayer.

Question 17

Which of the following best explains why plant cells do not burst when placed in a hypotonic solution?

Accepted Answer

The cell wall exerts turgor pressure that prevents excessive swelling.

Question 18

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

Accepted Answer

Providing a rigid structure to maintain cell shape

Question 19

Which of the following best describes pinocytosis?

Accepted Answer

The cell takes in extracellular fluid and dissolved solutes in a nonspecific manner.

Question 20

Which of the following statements about membrane potential is correct?

Accepted Answer

It is created by differences in the distribution of positive and negative ions across the membrane.

Membrane Structure and Function: Study Notes for General Biology

Guida di studio - Domande di pratica