Question 1

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

Accepted Answer

Movement of molecules with their concentration gradient without the need for a protein transporter.

Question 2

Facilitated diffusion differs from simple diffusion in that it:

Accepted Answer

Requires a protein transporter to move molecules across the membrane.

Question 3

Which equation best describes the rate of facilitated diffusion as substrate concentration increases?

Accepted Answer

$$v_0 = V$$_{max} \frac{[S]}{K_T + [S]}$$

Question 4

A researcher measures the rate of glucose transport into cells and finds that the rate plateaus at high glucose concentrations. What does this suggest about the transport mechanism?

Accepted Answer

Glucose is transported by facilitated diffusion.

Question 5

Which of the following statements about passive membrane transport is TRUE?

Accepted Answer

Facilitated diffusion is limited by the number of available transport proteins.

Question 6

In the context of membrane transport, what does the term 'saturable' mean?

Accepted Answer

The rate of transport reaches a maximum as all transport proteins become occupied.

Question 7

Which of the following is NOT a characteristic of simple diffusion?

Accepted Answer

It is saturable at high substrate concentrations.

Question 8

A cell is placed in a solution containing a high concentration of a nonpolar molecule. Which transport mechanism will most likely be responsible for the molecule entering the cell?

Accepted Answer

Simple diffusion

Question 9

Which of the following graphs best represents the rate of simple diffusion as a function of substrate concentration?

Accepted Answer

A straight line with a constant slope ($$y = mx + b)$$

Question 10

A patient has a genetic mutation that reduces the number of glucose transporters in their cell membranes. What effect will this have on glucose uptake?

Accepted Answer

Glucose uptake will be limited and reach saturation at lower concentrations.

Question 11

Which of the following is required for facilitated diffusion but NOT for simple diffusion?

Accepted Answer

A protein transporter

Question 12

If the rate of movement of a molecule across a membrane is measured to be hyperbolic with respect to concentration, which transport mechanism is most likely responsible?

Accepted Answer

Facilitated diffusion

Question 13

Which of the following would increase the rate of simple diffusion of a molecule across a membrane?

Accepted Answer

Increasing the concentration gradient of the molecule

Question 14

A scientist observes that the rate of transport of a molecule is linear at low concentrations but plateaus at high concentrations. What does this indicate?

Accepted Answer

The molecule is transported by facilitated diffusion.

Question 15

Which of the following is a key difference between facilitated diffusion and active transport?

Accepted Answer

Active transport requires energy input, while facilitated diffusion does not.

Passive Membrane Transport: Simple and Facilitated Diffusion

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