Question 1

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

Accepted Answer

A double layer of phospholipids with proteins and cholesterol embedded, allowing lateral movement

Question 2

What is the primary function of cholesterol in animal cell membranes at low temperatures?

Accepted Answer

It prevents the membrane from becoming too rigid by disrupting phospholipid packing

Question 3

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

Accepted Answer

It will gain water and burst (lyse)

Question 4

Which of the following molecules can most easily cross the plasma membrane without the help of a transport protein?

Accepted Answer

Oxygen ($$O_2)$$

Question 5

What is the main difference between passive and active transport across the plasma membrane?

Accepted Answer

Active transport requires energy input (often ATP) to move substances against their concentration gradient

Question 6

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

Accepted Answer

Their kinks prevent tight packing of phospholipids

Question 7

A plant cell is placed in a hypertonic solution. What process occurs and what is the result?

Accepted Answer

Plasmolysis; the cell membrane pulls away from the cell wall

Question 8

Which type of membrane protein is most likely to function as a channel for ions?

Accepted Answer

Integral transmembrane protein

Question 9

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

Accepted Answer

Active transport

Question 10

Which of the following best describes cotransport in biological membranes?

Accepted Answer

The downhill diffusion of one solute powers the uphill transport of another

Question 11

Which process is responsible for the uptake of large macromolecules into a cell?

Accepted Answer

Endocytosis

Question 12

What is the main role of aquaporins in the plasma membrane?

Accepted Answer

To allow rapid passive movement of water across the membrane

Question 13

Which of the following statements about membrane potential is correct?

Accepted Answer

It is the voltage across the membrane due to the unequal distribution of ions

Question 14

A cell is placed in an isotonic solution. What will happen to the movement of water across the plasma membrane?

Accepted Answer

Water will move in and out at equal rates, resulting in no net change

Question 15

Which of the following best describes the sidedness of membranes?

Accepted Answer

The inner and outer faces of the membrane have distinct distributions of proteins, lipids, and carbohydrates

Question 16

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

Accepted Answer

DNA replication

Question 17

Which scenario best illustrates the concept of selective permeability?

Accepted Answer

A membrane allows $$CO_2 to $$pass freely but restricts glucose movement

Question 18

Which of the following equations correctly represents the movement of water during osmosis?

Accepted Answer

$$H_2O$$ moves from a region of lower solute concentration to higher solute concentration

Question 19

Which of the following best explains why plant cells do not burst in hypotonic solutions?

Accepted Answer

The cell wall provides structural support and prevents excessive expansion

Question 20

Which of the following is an example of bulk transport?

Accepted Answer

Exocytosis of insulin from pancreatic cells

Membrane Structure and Function: Study Guide for General Biology

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