Question 1

Which of the following best describes the process of diffusion across a biological membrane?

Accepted Answer

Molecules move from an area of higher concentration to an area of lower concentration, down their concentration gradient, without energy input.

Question 2

A red blood cell is placed in a solution and begins to swell 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 facilitated diffusion is correct?

Accepted Answer

Facilitated diffusion uses specific transport proteins to move substances down their concentration gradient.

Question 4

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

Accepted Answer

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

Question 5

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

Accepted Answer

They allow rapid passive diffusion of water across the membrane.

Question 6

In an experiment, red blood cells from 15-day-old and 1-month-old guinea pigs are incubated in a 300 mM glucose solution. The younger cells show a higher rate of glucose uptake. Which of the following is the most likely explanation for this observation?

Accepted Answer

Younger cells have more active glucose carrier proteins facilitating diffusion.

Question 7

Which of the following scenarios best illustrates dynamic equilibrium in the context of diffusion?

Accepted Answer

Molecules continue to move across the membrane, but there is no net change in concentration on either side.

Question 8

A nerve cell uses potassium ion channels that open in response to electrical stimuli. What type of membrane protein is this, and what is its function?

Accepted Answer

Gated channel protein; allows potassium ions to diffuse down their concentration gradient when open.

Question 9

Which of the following best describes the movement of water during osmosis?

Accepted Answer

Water moves from a region of higher free water concentration (lower solute concentration) to a region of lower free water concentration (higher solute concentration).

Question 10

Which adaptation allows Paramecium caudatum to survive in a hypotonic environment?

Accepted Answer

It uses a contractile vacuole to pump out excess water.

Question 11

If a cell is placed in an isotonic solution, what will happen to its volume over time?

Accepted Answer

The cell volume will remain stable with no net movement of water.

Question 12

Which of the following statements about the diffusion of two solutes across a membrane is correct?

Accepted Answer

Each solute diffuses independently down its own concentration gradient.

Question 13

Which of the following best explains why plant cells become flaccid in an isotonic solution?

Accepted Answer

There is no net movement of water, so turgor pressure is lost.

Question 14

A scientist observes that a certain ion can only cross the cell membrane when a specific chemical signal is present. Which type of membrane protein is most likely responsible for this observation?

Accepted Answer

Gated ion channel

Question 15

Which of the following is a key difference between channel proteins and carrier proteins in facilitated diffusion?

Accepted Answer

Carrier proteins undergo a shape change to move solutes, while channel proteins provide a continuous passage.

Question 16

A solution outside a cell has a higher solute concentration than the cytoplasm. What will happen to an animal cell placed in this solution?

Accepted Answer

The cell will lose water and shrivel.

Question 17

Which of the following best describes the role of selective permeability in biological membranes?

Accepted Answer

It regulates the diffusion rates of different molecules based on their properties.

Question 18

Which of the following equations best represents the relationship between solute concentration and water movement during osmosis?

Accepted Answer

$$ 	ext{Water moves from} ightarrow 	ext{Lower solute concentration} ightarrow 	ext{Higher solute concentration} $$

Question 19

Which of the following is the dependent variable in the experiment measuring glucose uptake in guinea pig red blood cells?

Accepted Answer

The concentration of glucose inside the cells

Question 20

Which of the following best explains why bacteria and archaea living in hypersaline environments must regulate their internal solute concentrations?

Accepted Answer

To prevent water loss and maintain cellular function

Passive Transport and Membrane Dynamics: Diffusion, Osmosis, and Facilitated Diffusion

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