Question 1

Which of the following molecules would most easily pass through a cell's phospholipid bilayer without the aid of a transport protein?

Accepted Answer

A small hydrophobic molecule such as oxygen ($O_2$)

Question 2

A scientist is culturing a prokaryotic cell in a cold environment. Which membrane adaptation would most likely help the cell maintain proper membrane fluidity?

Accepted Answer

Increasing the proportion of unsaturated fatty acid tails in membrane phospholipids

Question 3

Which of the following best describes the effect of cholesterol on animal cell membranes at normal physiological temperatures (around $37^	ext{\circ}$C)?

Accepted Answer

Cholesterol stabilizes the membrane by limiting the movement of phospholipid fatty acid tails, making the membrane less fluid.

Question 4

A red blood cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell?

Accepted Answer

It will lose water and shrink (crenate) due to osmosis.

Question 5

Which of the following statements about passive transport is correct?

Accepted Answer

Passive transport involves the movement of substances down their concentration gradient without energy investment.

Question 6

A plant cell is placed in a hypotonic solution. What is the expected outcome?

Accepted Answer

The cell will become turgid as water enters, pressing the plasma membrane against the cell wall.

Question 7

Which of the following factors would increase the permeability of a cell membrane?

Accepted Answer

Increasing the proportion of unsaturated fatty acid tails in phospholipids

Question 8

Which of the following is a characteristic feature of a carrier protein in the plasma membrane?

Accepted Answer

It is specific for a particular type of molecule and changes shape to transport it.

Question 9

A dialysis bag containing a 0.1 M solution of glucose is placed in a beaker containing a 0.5 M solution of sucrose. The bag is permeable to water but not to glucose or sucrose. What will happen?

Accepted Answer

Water will move out of the bag, causing it to shrink.

Question 10

Which equation best describes the net movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$\Delta \Psi = \Psi_{inside} - \Psi_{outside}$, where $\Psi$ is water potential

Question 11

Which of the following is true about facilitated diffusion?

Accepted Answer

It uses transport proteins to move molecules down their concentration gradient.

Question 12

Which type of transport protein is responsible for allowing water to cross the plasma membrane rapidly?

Accepted Answer

Aquaporin channel protein

Question 13

Which of the following statements about membrane fluidity is correct?

Accepted Answer

Shorter fatty acid tails increase membrane fluidity.

Question 14

A Paramecium living in freshwater uses a contractile vacuole. What is the main function of this organelle?

Accepted Answer

To pump excess water out of the cell to prevent bursting

Question 15

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

Accepted Answer

The cell wall provides structural support and limits water uptake.

Question 16

Which of the following would decrease the permeability of a cell membrane to small hydrophilic molecules?

Accepted Answer

Increasing the proportion of saturated fatty acid tails in phospholipids

Question 17

Which of the following is NOT a factor that affects membrane permeability?

Accepted Answer

Number of ribosomes in the cell

Question 18

Which of the following best describes the movement of molecules during simple diffusion?

Accepted Answer

Molecules move randomly but overall from high to low concentration.

Question 19

Which of the following is true about ion channels in the plasma membrane?

Accepted Answer

They are usually gated and allow passive diffusion of specific ions in response to a stimulus.

Question 20

Which of the following would most likely increase the rigidity of a cell membrane?

Accepted Answer

Increasing the proportion of saturated fatty acid tails in phospholipids

Membrane Structure and Function: Permeability and Transport

Study Guide - Practice Questions

Study Guide - Flashcards