Q: Which of the following equations best represents the movement of water during osmosis?

$$\text{Water moves from a region of lower solute concentration to a region of higher solute concentration across a selectively permeable membrane.}$$

Question 1

Which of the following best explains why membranes rich in unsaturated fatty acids remain fluid at lower temperatures?

Accepted Answer

Unsaturated fatty acid tails have kinks that prevent tight packing of phospholipids.

Question 2

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

Accepted Answer

The solution is hypertonic; water moves out of the cell.

Question 3

Which of the following is a function of membrane proteins that is critical for the immune system’s ability to distinguish self from non-self?

Accepted Answer

Cell-cell recognition

Question 4

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

Accepted Answer

Active transport

Question 5

A plant cell is placed in a hypotonic solution. What will happen to the cell, and what is the term for the pressure that develops?

Accepted Answer

The cell will become turgid due to turgor pressure.

Question 6

Which of the following best describes the role of cholesterol in animal cell membranes at different temperatures?

Accepted Answer

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

Question 7

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

Accepted Answer

O$$_2$$

Question 8

A patient with diarrhea is given a solution containing both NaCl and glucose. Why is this treatment effective?

Accepted Answer

Na$$^+$$ and glucose are co-transported into intestinal cells, increasing water absorption.

Question 9

Which of the following statements about facilitated diffusion is correct?

Accepted Answer

It requires transport proteins but does not require energy.

Question 10

Familial hypercholesterolemia is caused by defective LDL receptor proteins. What is the consequence of this defect?

Accepted Answer

Cholesterol accumulates in the blood, increasing risk of heart disease.

Question 11

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

Accepted Answer

Specific molecules bind to receptors, triggering vesicle formation.

Question 12

Which of the following equations best represents the movement of water during osmosis?

Accepted Answer

$$	ext{Water moves from a region of lower solute concentration to a region of higher solute concentration across a selectively permeable membrane.}$$

Question 13

Which of the following is true about the sodium-potassium pump in animal cells?

Accepted Answer

It moves 3 Na$$^+$$ ions out and 2 K$$^+$$ ions into the cell, using ATP.

Question 14

Which of the following best explains why aquaporins are necessary for cells?

Accepted Answer

They greatly increase the rate of water transport across the membrane.

Question 15

A Paramecium living in a freshwater pond uses a contractile vacuole to:

Accepted Answer

Expel excess water that enters by osmosis.

Question 16

Which of the following is a real-life example of bulk transport via exocytosis?

Accepted Answer

Secretion of insulin by pancreatic cells.

Question 17

Which of the following best describes the electrochemical gradient?

Accepted Answer

It is the combination of the chemical concentration gradient and the electrical gradient across a membrane.

Question 18

Which of the following statements about the fluid mosaic model is correct?

Accepted Answer

Membrane proteins are embedded in a fluid bilayer of phospholipids and can move laterally.

Membrane Structure and Function: Regulation of Cellular Transport

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