Question 1

Which of the following best describes why phospholipids form a bilayer in aqueous environments?

Accepted Answer

Their hydrophilic heads interact with water, while their hydrophobic tails avoid water.

Question 2

A red blood cell is placed in a solution and swells until it bursts. Which term best describes the tonicity of the solution, and why does this occur?

Accepted Answer

Hypotonic; water moves into the cell due to lower solute concentration outside.

Question 3

Which of the following is a function of membrane proteins that is critical for immune system recognition?

Accepted Answer

Cell-cell recognition

Question 4

A plant cell is placed in a hypertonic solution. What is the most likely outcome, and what is this process called?

Accepted Answer

The cell undergoes plasmolysis and shrinks.

Question 5

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

Accepted Answer

Molecules move down their concentration gradient with the help of transport proteins.

Question 6

Which of the following correctly matches the type of transport with its description?

Accepted Answer

Active transport: movement of molecules against their concentration gradient using energy

Question 7

A scientist observes that a certain protein spans the entire plasma membrane and has both hydrophobic and hydrophilic regions. This protein is most likely:

Accepted Answer

An integral protein

Question 8

Which of the following best describes the movement of sodium and potassium ions by the sodium-potassium pump?

Accepted Answer

Sodium ions are pumped out of the cell and potassium ions are pumped in, both against their concentration gradients.

Question 9

Which of the following processes is responsible for the uptake of large particles, such as bacteria, by white blood cells?

Accepted Answer

Phagocytosis

Question 10

A cell is placed in a solution with a higher solute concentration than its cytoplasm. What will happen to the cell, and why?

Accepted Answer

It will shrink because water leaves the cell.

Question 11

Which of the following best describes the role of cholesterol in the animal cell membrane?

Accepted Answer

It helps maintain membrane fluidity under different temperature conditions.

Question 12

Which of the following is true about the movement of molecules during diffusion?

Accepted Answer

Molecules move from areas of high concentration to low concentration.

Question 13

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

Accepted Answer

They allow water to diffuse rapidly across the plasma membrane.

Question 14

A mutation causes a cell to lack functional proton pumps. Which process would be most directly affected in plants?

Accepted Answer

Generation of membrane potential

Question 15

Which of the following scenarios best illustrates osmoregulation?

Accepted Answer

A freshwater fish excreting large amounts of dilute urine to maintain water balance

Question 16

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

Accepted Answer

Phospholipids and proteins can move laterally within the layer, contributing to membrane fluidity.

Question 17

Which of the following best describes the path of a protein destined for secretion from the cell?

Accepted Answer

Rough ER → Golgi apparatus → Vesicle → Cell membrane

Question 18

Which of the following is an example of a molecule moving up its concentration gradient?

Accepted Answer

Sodium ions being pumped out of a neuron by the sodium-potassium pump

Question 19

Which of the following best explains why a cell in an isotonic solution does not change in size?

Accepted Answer

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

Question 20

Which of the following processes involves the cell taking in extracellular fluid and dissolved solutes by forming small vesicles?

Accepted Answer

Pinocytosis

The Cell Membrane: Structure, Function, and Transport Mechanisms

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