Question 1

Which of the following best explains why cell membranes are described as a 'fluid mosaic'?

Accepted Answer

The membrane is a dynamic structure with proteins and lipids that can move laterally within the bilayer.

Question 2

A hospital patient receives an intravenous solution that is hypotonic relative to their blood cells. What is the most likely outcome for the patient's red blood cells?

Accepted Answer

The red blood cells will swell and may burst due to water entering the cells.

Question 3

Which of the following molecules would most likely require a transport protein to cross the plasma membrane?

Accepted Answer

Sucrose

Question 4

How does cholesterol affect membrane fluidity at moderate temperatures?

Accepted Answer

It decreases membrane fluidity by restraining phospholipid movement.

Question 5

A freshwater plant cell is placed in a hypertonic solution. What will happen to the cell?

Accepted Answer

It will lose water and undergo plasmolysis.

Question 6

Which of the following best describes the function of the sodium-potassium pump ($$Na^+/K^+$$ ATPase) in animal cells?

Accepted Answer

It uses ATP to move sodium ions out of the cell and potassium ions into the cell, both against their concentration gradients.

Question 7

Which of the following changes would you predict in the composition of a trout's plasma membrane as the water temperature decreases?

Accepted Answer

Increase the proportion of unsaturated fatty acids to maintain membrane fluidity.

Question 8

Which of the following is an example of active transport?

Accepted Answer

Pumping protons ($$H^+) $$into the stomach lining using ATP.

Question 9

A cell is placed in an isotonic solution. Which of the following best describes the movement of water?

Accepted Answer

Water moves in and out of the cell at equal rates.

Question 10

Which of the following best describes the process of receptor-mediated endocytosis?

Accepted Answer

The cell takes in specific molecules after they bind to receptors on the cell surface.

Question 11

Which of the following statements about membrane proteins is correct?

Accepted Answer

Integral membrane proteins penetrate the hydrophobic core of the lipid bilayer.

Question 12

Which type of cell signaling involves the release of hormones that travel through the bloodstream to reach distant target cells?

Accepted Answer

Endocrine signaling

Question 13

Which of the following best explains why steroid hormones can bind to intracellular receptors?

Accepted Answer

Steroid hormones are hydrophobic and can diffuse through the lipid bilayer.

Question 14

A pharmaceutical company wants to design a drug to lower blood sugar by interfering with the epinephrine signaling pathway. Which target would be most effective?

Accepted Answer

A compound that inhibits adenylyl cyclase, preventing cAMP production.

Question 15

Which of the following best describes the role of a phosphorylation cascade in cell signaling?

Accepted Answer

It amplifies the signal by activating multiple proteins at each step.

Question 16

Which of the following is true regarding facilitated diffusion?

Accepted Answer

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

Question 17

Which of the following best describes the function of aquaporins?

Accepted Answer

They allow rapid passive movement of water molecules across the membrane.

Question 18

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

Accepted Answer

A cell membrane allows some molecules to cross more easily than others.

Question 19

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

Accepted Answer

They provide a cell 'signature' for cell-cell recognition.

Question 20

Which of the following best describes the movement of ions through a voltage-gated ion channel?

Accepted Answer

Ions move down their concentration gradient when the channel opens in response to a change in membrane potential.

Membrane Transport and Cell Signaling: Structure and Function of the Plasma Membrane (chapter 5)

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