Question 1

Which of the following molecules would most readily diffuse across a protein-free artificial lipid bilayer, as shown in the second image?

Accepted Answer

O$$_2$$

Question 2

A red blood cell is placed in a hypotonic solution. Based on the images of animal and plant cells in different tonicities, what is the most likely outcome for the red blood cell?

Accepted Answer

It will lyse (burst).

Question 3

Which of the following best describes the difference between simple diffusion and facilitated diffusion, as shown in the graph comparing their rates?

Accepted Answer

Facilitated diffusion shows saturation kinetics, while simple diffusion does not.

Question 4

A cell is actively transporting Na$$ ^+ $$ ions out of the cytoplasm against their concentration gradient. Which type of transport is being used, and what is the energy source?

Accepted Answer

Active transport; ATP hydrolysis

Question 5

Which of the following statements about osmosis is correct, as illustrated in the osmosis diagram?

Accepted Answer

Water moves from a region of low solute concentration to high solute concentration.

Question 6

Which of the following best explains why ions such as Na$$ ^+ $$ and Cl$$ ^- $$ cannot easily cross a protein-free lipid bilayer?

Accepted Answer

They are charged and cannot pass through the hydrophobic core of the bilayer.

Question 7

A patient is given an intravenous solution that is hypertonic relative to their blood plasma. What is the most likely effect on their red blood cells?

Accepted Answer

The cells will shrink (crenate).

Question 8

Which of the following is a characteristic of active transport but NOT of facilitated diffusion?

Accepted Answer

Requirement for metabolic energy (e.g., ATP)

Question 9

The sodium-glucose co-transporter (SGLT) uses the energy from Na$$ ^+ $$ moving down its electrochemical gradient to transport glucose into the cell against its concentration gradient. What type of transport is this?

Accepted Answer

Secondary active transport (symport)

Question 10

Which of the following equations correctly represents the free energy change ($$\Delta G) $$for the movement of a non-charged solute across a membrane?

Accepted Answer

$$\Delta G = RT \ln \left( \frac{[S]_{out}}{[S]_{in}} \right)$$

Question 11

A mutation in a gene encoding an aquaporin protein would most directly affect which cellular process?

Accepted Answer

Osmosis (water transport)

Question 12

Which of the following best describes the function of the Na$$ ^+ /K$ ^+ $$ ATPase pump, as shown in the relevant diagram?

Accepted Answer

It exchanges Na$$ ^+ $$ for K$$ ^+ $$ using the energy from ATP hydrolysis.

Question 13

Which of the following is true regarding the rate of facilitated diffusion as solute concentration increases?

Accepted Answer

It increases and then plateaus due to saturation of carrier proteins.

Question 14

A cell is placed in a solution and water moves into the cell, causing it to swell. What can you conclude about the tonicity of the solution relative to the cell?

Accepted Answer

The solution is hypotonic.

Question 15

Which of the following best explains why carrier-mediated transport can become saturated, as shown in the facilitated diffusion graph?

Accepted Answer

All available carrier proteins are occupied by substrate.

Question 16

Which of the following is an example of indirect (secondary) active transport?

Accepted Answer

Glucose transport via SGLT using Na$$ ^+ $$ gradient

Question 17

Which of the following best describes the directionality of active transport?

Accepted Answer

It moves solutes up their concentration gradient.

Question 18

Which of the following is a property shared by both facilitated diffusion and active transport?

Accepted Answer

Both require specific membrane proteins.

Question 19

A patient with a genetic defect in the GLUT1 transporter would most likely have impaired transport of which molecule?

Accepted Answer

Glucose

Question 20

Which of the following best describes the role of ATP in the function of the Na$$ ^+ /K$ ^+ $$ ATPase?

Accepted Answer

ATP hydrolysis provides the energy for conformational changes in the pump.

Transport Across Membranes: Overcoming the Permeability Barrier

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