Question 1

Which of the following best describes the structure of a phospholipid molecule found in cell membranes?

Accepted Answer

A molecule with two hydrophobic fatty acid tails and a hydrophilic phosphate head

Question 2

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

Accepted Answer

Cholesterol reduces membrane fluidity at high temperatures and prevents solidification at low temperatures

Question 3

A red blood cell is placed in a solution and swells until it bursts. Which type of solution was the cell placed in?

Accepted Answer

A hypotonic solution

Question 4

Which of the following best explains why the plasma membrane is described as a 'fluid mosaic'?

Accepted Answer

It is composed of a variety of proteins embedded in or attached to a fluid phospholipid bilayer

Question 5

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

Accepted Answer

Synthesis of DNA

Question 6

A cell is placed in a solution containing a higher concentration of solute than inside the cell. What will most likely happen to the cell?

Accepted Answer

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

Question 7

Which of the following best describes facilitated diffusion?

Accepted Answer

The passive movement of molecules across a membrane via transport proteins

Question 8

Which equation correctly represents the calculation of water potential ($$\Psi) in $$plant cells?

Accepted Answer

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

Question 9

A scientist observes that a certain protein spans the entire plasma membrane and allows ions to pass through. Which type of protein is this most likely to be?

Accepted Answer

A channel protein

Question 10

Which of the following processes requires energy input from the cell?

Accepted Answer

Active transport

Question 11

A white blood cell engulfs a bacterium by wrapping its plasma membrane around it and forming a vesicle. What is this process called?

Accepted Answer

Phagocytosis

Question 12

Which of the following best explains why ions cannot easily cross the lipid bilayer of the plasma membrane?

Accepted Answer

Ions are charged and hydrophilic, so they cannot pass through the hydrophobic core of the membrane

Question 13

Which of the following scenarios best illustrates the concept of selective permeability?

Accepted Answer

A cell membrane allows oxygen and carbon dioxide to pass freely but restricts the movement of glucose

Question 14

A plant cell is placed in a solution with a lower water potential than the cell. What will happen to the cell?

Accepted Answer

Water will leave the cell, causing the cell to become plasmolyzed

Question 15

Which of the following is a correct statement about the sodium-potassium pump?

Accepted Answer

It moves 3 sodium ions out of the cell and 2 potassium ions into the cell using ATP

Question 16

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

Accepted Answer

They facilitate the rapid movement of water molecules across the membrane

Question 17

A cell is observed to have a high concentration of glucose inside and a low concentration outside. Which transport mechanism is most likely responsible for moving more glucose into the cell?

Accepted Answer

Active transport via a carrier protein

Question 18

Which of the following best explains the difference between exocytosis and endocytosis?

Accepted Answer

Exocytosis moves materials out of the cell, while endocytosis brings materials into the cell

Question 19

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

Accepted Answer

Cell-cell recognition

Question 20

A researcher adds a substance to a cell culture that blocks all ATP production. Which of the following processes would be most directly affected?

Accepted Answer

Active transport of ions across the membrane

Cell Membranes: Structure, Function, and Transport Mechanisms

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