Question 1

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

Accepted Answer

A dynamic bilayer of amphipathic phospholipids with proteins and other molecules embedded and moving laterally.

Question 2

A red blood cell is placed in a solution and begins to swell and eventually bursts. Which of the following best describes the tonicity of the solution relative to the cell, and the direction of water movement?

Accepted Answer

The solution is hypotonic; water moves into the cell.

Question 3

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

Accepted Answer

Cholesterol decreases membrane fluidity at moderate temperatures but prevents solidification at low temperatures.

Question 4

Which of the following molecules would most easily diffuse through a pure phospholipid bilayer without the aid of a transport protein?

Accepted Answer

Oxygen ($$\mathrm{O_2$})$$

Question 5

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

Accepted Answer

The cell will undergo plasmolysis as the plasma membrane pulls away from the cell wall.

Question 6

Which of the following best explains why facilitated diffusion does not require energy input from the cell?

Accepted Answer

It moves substances down their concentration gradient through specific transport proteins.

Question 7

The sodium-potassium pump is an example of which type of membrane transport, and what is the net result of its activity?

Accepted Answer

Active transport; creates a higher $$\mathrm{K^+}$$ concentration inside and a higher $$\mathrm{Na^+}$$ concentration outside the cell.

Question 8

Which of the following is a function of membrane carbohydrates?

Accepted Answer

Acting as markers for cell recognition and identification.

Question 9

A patient with familial hypercholesterolemia has defective LDL receptors. What is the most direct consequence of this defect at the cellular level?

Accepted Answer

Cholesterol accumulates in the blood because cells cannot take up LDL via receptor-mediated endocytosis.

Question 10

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

Accepted Answer

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

Question 11

A cell is placed in an isotonic solution. Which of the following statements is true regarding water movement?

Accepted Answer

Water moves in and out of the cell at equal rates, resulting in no net movement.

Question 12

Which of the following is a property of integral membrane proteins?

Accepted Answer

They penetrate the hydrophobic core of the lipid bilayer.

Question 13

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

Accepted Answer

Their kinked tails prevent tight packing of phospholipids.

Question 14

Which of the following is an example of bulk transport across the plasma membrane?

Accepted Answer

Exocytosis of insulin from pancreatic cells.

Question 15

A cell uses a proton pump to create a gradient of $$\mathrm{H^+}$$ ions across its membrane. Which process can use this gradient to drive the active transport of another molecule, such as sucrose, into the cell?

Accepted Answer

Cotransport (secondary active transport)

Question 16

Which of the following best describes the difference between phagocytosis and pinocytosis?

Accepted Answer

Phagocytosis engulfs large particles or cells, while pinocytosis engulfs extracellular fluid and dissolved solutes.

Question 17

Which of the following equations best represents the movement of water during osmosis across a selectively permeable membrane?

Accepted Answer

$$	ext{Water moves from an area of lower solute concentration to an area of higher solute concentration}$$

Question 18

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

Accepted Answer

Synthesis of phospholipids.

Question 19

A glucose carrier protein in the plasma membrane will transport which of the following molecules?

Accepted Answer

Only glucose, due to its specificity.

Membrane Structure and Function: Study Notes (Campbell Biology, Chapter 7)

Guida di studio - Domande di pratica

Study guide - Flashcard