Question 1

Which of the following best explains why phospholipids form bilayers in aqueous environments?

Accepted Answer

Their hydrophilic heads interact with water, while their hydrophobic tails avoid water, causing them to arrange into bilayers.

Question 2

A red blood cell is placed in a solution and swells until it bursts. Which of the following best describes the tonicity of the solution relative to the cell?

Accepted Answer

The solution is hypotonic to the cell.

Question 3

Which of the following statements about saturated and unsaturated fatty acids is correct?

Accepted Answer

Saturated fatty acids have no double bonds and are typically solid at room temperature.

Question 4

Which of the following best describes the function of cholesterol in animal cell membranes?

Accepted Answer

It increases membrane fluidity at low temperatures and decreases it at high temperatures.

Question 5

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

Accepted Answer

The cell will lose water and the plasma membrane will pull away from the cell wall (plasmolysis).

Question 6

Which of the following is a key difference between passive and active transport across cell membranes?

Accepted Answer

Active transport requires energy input to move substances against their concentration gradient.

Question 7

Which of the following best describes facilitated diffusion?

Accepted Answer

Movement of molecules down their concentration gradient through a membrane protein, without energy input.

Question 8

Which of the following equations correctly represents the relationship for the rate of diffusion ($J$) according to Fick's first law?

Accepted Answer

$J = -D \frac{dC}{dx}$

Question 9

Which of the following is a function of membrane proteins?

Accepted Answer

They act as enzymes, receptors, and transporters for specific molecules.

Question 10

A cell is placed in a solution containing a higher concentration of solutes than the cytoplasm. Which process will most likely occur?

Accepted Answer

Water will move out of the cell by osmosis.

Question 11

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

Accepted Answer

Their double bonds create kinks, preventing tight packing of phospholipids.

Question 12

Which of the following statements about the sodium-potassium pump is correct?

Accepted Answer

It uses ATP to move sodium ions out of the cell and potassium ions into the cell.

Question 13

Which of the following best describes the amphipathic nature of phospholipids?

Accepted Answer

They have both hydrophilic and hydrophobic regions.

Question 14

A patient is given an intravenous solution that is hypotonic relative to their blood plasma. What is a possible consequence?

Accepted Answer

Red blood cells may swell and burst due to water influx.

Question 15

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

Accepted Answer

They span the lipid bilayer and have hydrophobic regions embedded in the membrane.

Question 16

Which of the following best describes the process of osmosis?

Accepted Answer

The movement of water molecules from low to high solute concentration across a selectively permeable membrane.

Question 17

Which of the following statements about diffusion is correct?

Accepted Answer

Diffusion is the movement of molecules from an area of high concentration to an area of low concentration.

Question 18

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

Accepted Answer

They have a rigid cell wall that prevents excessive expansion.

Question 19

Which of the following is a function of the fluid mosaic model of membranes?

Accepted Answer

It explains that membranes are dynamic, with proteins and lipids able to move laterally within the bilayer.

Question 20

Which of the following best describes the role of aquaporins in cells?

Accepted Answer

They are channel proteins that facilitate rapid water movement across the membrane.

Membrane Structure, Lipids, and Transport in General Biology

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