$$\text{Net movement of water} \propto \text{difference in solute concentration across the membrane}$$

It moves $$\text{Na}^+$$ out of the cell and $$\text{K}^+$$ into the cell.

Question 1

Which of the following best describes the amphipathic nature of phospholipids in the plasma membrane?

Accepted Answer

Phospholipids have both hydrophilic and hydrophobic regions, with hydrophobic tails facing inward and hydrophilic heads facing outward.

Question 2

According to the fluid mosaic model, which statement is correct about membrane proteins?

Accepted Answer

Membrane proteins can move laterally within the bilayer and often form groups that carry out common functions.

Question 3

How does cholesterol affect membrane fluidity at different temperatures in animal cells?

Accepted Answer

Cholesterol decreases fluidity at high temperatures and increases fluidity at low temperatures.

Question 4

A cell is placed in a hypertonic solution. What will happen to the cell and in which direction will water move?

Accepted Answer

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

Question 5

Which type of transport protein is responsible for moving water rapidly across the plasma membrane?

Accepted Answer

Aquaporin

Question 6

Which equation best represents the movement of solutes during osmosis across a selectively permeable membrane?

Accepted Answer

$$	ext{Net movement of water} \propto 	ext{difference in solute concentration across the membrane}$$

Question 7

Which of the following molecules can most easily diffuse through the lipid bilayer without the help of a transport protein?

Accepted Answer

Oxygen ($$	ext{O}_2)$$

Question 8

What is the main function of glycoproteins and glycolipids in the plasma membrane?

Accepted Answer

They serve as markers for cell recognition and identification.

Question 9

Which process requires energy input in the form of ATP to move substances against their concentration gradient?

Accepted Answer

Active transport

Question 10

The sodium-potassium pump in animal cells moves ions in which direction?

Accepted Answer

It moves $$	ext{Na}^+$$ out of the cell and $$	ext{K}^+$$ into the cell.

Question 11

Which of the following best explains why plant cells become turgid in a hypotonic solution?

Accepted Answer

Water enters the cell, but the cell wall prevents excessive swelling, resulting in turgor pressure.

Question 12

Which type of endocytosis is most specific for the uptake of certain molecules, such as cholesterol via LDL particles?

Accepted Answer

Receptor-mediated endocytosis

Question 13

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

Accepted Answer

The cell will undergo plasmolysis as water leaves the cell.

Question 14

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

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

Question 15

Which equation best describes the electrochemical gradient that drives ion movement across membranes?

Accepted Answer

$$\Delta G = RT \ln \left( \frac{[C]_{in}}{[C]_{out}} \right) + zF\Delta V$$

Question 16

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

Accepted Answer

Synthesizing phospholipids for the membrane

Question 17

Which type of bulk transport is used by pancreatic cells to secrete insulin into the bloodstream?

Accepted Answer

Exocytosis

Question 18

Which of the following best describes the role of the proton pump in plant cells?

Accepted Answer

It generates a $$	ext{H}^+$$ gradient across the membrane, which is used for cotransport of other substances.

Question 19

Which of the following statements about the sidedness of membranes is correct?

Accepted Answer

Membranes have distinct inside and outside faces with different compositions.

Question 20

Which scenario best illustrates coupled transport (cotransport) in animal cells?

Accepted Answer

Glucose is transported into intestinal cells by coupling its movement to the diffusion of $$	ext{Na}^+$$ down its gradient.

Membrane Structure and Function – Study Notes

Study Guide - Practice Questions