Question

question 7 / 10
which characteristic of facilitated diffusion distinguishes it from active transport?

a. it moves water across the plasma membrane.

b. it moves materials against the concentration gradient.

c. it occurs without the input of atp.

d. it uses proteins embedded in the plasma membrane.

Explanation:

1. Analyze Option A: Movement of water across the plasma membrane is osmosis, not a key distinction between facilitated diffusion and active transport. So A is incorrect.
2. Analyze Option B: Facilitated diffusion moves materials down the concentration gradient, while active transport moves against it. So B is incorrect as it describes active transport, not facilitated diffusion.
3. Analyze Option C: Facilitated diffusion is a passive process (no ATP input), while active transport requires ATP. This is a key distinction. So C is correct.
4. Analyze Option D: Both facilitated diffusion (uses channel/carrier proteins) and active transport (uses pump proteins) use membrane - embedded proteins. So D is not a distinguishing factor.

Answer:

C. It occurs without the input of ATP.