Question 1

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

Accepted Answer

A dynamic bilayer of phospholipids with proteins and other molecules floating and moving laterally within it.

Question 2

Which component of the plasma membrane is primarily responsible for its selective permeability?

Accepted Answer

Phospholipid bilayer

Question 3

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

Accepted Answer

It will swell and may burst as water enters the cell.

Question 4

Which of the following statements about cholesterol in animal cell membranes is correct?

Accepted Answer

Cholesterol acts as a fluidity buffer, reducing fluidity at high temperatures and preventing solidification at low temperatures.

Question 5

Which of the following molecules would diffuse most rapidly across a pure phospholipid bilayer?

Accepted Answer

O2

Question 6

Facilitated diffusion differs from simple diffusion in that facilitated diffusion:

Accepted Answer

Requires membrane proteins to transport substances across the membrane.

Question 7

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

Accepted Answer

Plant cells have a rigid cell wall that prevents excessive expansion.

Question 8

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

Accepted Answer

Active transport

Question 9

Which equation best represents the movement of water during osmosis?

Accepted Answer

$$H_2O$$ moves from an area of higher free water concentration to an area of lower free water concentration across a selectively permeable membrane.

Question 10

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

Accepted Answer

Energy storage

Question 11

A cell is placed in a solution and water moves out of the cell. Which term best describes the solution?

Accepted Answer

Hypertonic

Question 12

Which of the following best describes cotransport?

Accepted Answer

The active transport of one solute directly drives the passive transport of another solute.

Question 13

Which process requires energy but does NOT require transport proteins?

Accepted Answer

Bulk transport (endocytosis/exocytosis)

Question 14

Which of the following is a correct statement about the role of glycoproteins in the plasma membrane?

Accepted Answer

They are involved in cell-cell recognition.

Question 15

Which of the following best explains why ions such as Na+ and K+ cannot easily cross the plasma membrane?

Accepted Answer

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

Question 16

Which of the following scenarios best illustrates the concept of membrane fluidity?

Accepted Answer

Phospholipids and proteins move laterally within the layer, allowing for rapid mixing after cell fusion.

Question 17

Which of the following is true about aquaporins?

Accepted Answer

They are channel proteins that facilitate the rapid movement of water across the membrane.

Question 18

Which of the following best describes the effect of saturated versus unsaturated fatty acid tails on membrane fluidity?

Accepted Answer

Unsaturated tails increase fluidity by preventing tight packing.

Question 19

Which of the following is an example of active transport?

Accepted Answer

Sodium ions being pumped out of a cell using ATP

Question 20

Which of the following best explains why facilitated diffusion is considered passive transport?

Accepted Answer

It relies on membrane proteins but does not require energy input, moving substances down their concentration gradient.

Membrane Structure and Function: Study Notes for General Biology

Guida di studio - Domande di pratica