Question

question 9 / 10
a pipe carries excess rainwater into a lake. the rainwater has picked up dissolved nitrates from surrounding lawns. which of the following is a consequence of simple diffusion of the nitrates in the lake?

a. a concentration gradient of nitrates is created and maintained.

b. the total amount of dissolved nitrate in the lake water decreases.

c. nitrate concentration decreases in some places and increases in others.

d. energy is required to move the nitrates from one end of the lake to the other.

Explanation:

1. Recall the concept of simple diffusion: molecules move from an area of higher concentration to an area of lower concentration.
2. Analyze Option A: Simple diffusion works to eliminate a concentration gradient, not maintain it. So A is incorrect.
3. Analyze Option B: The total amount of dissolved nitrate in the lake water (from the rainwater input) does not decrease due to diffusion alone (diffusion is about movement, not removal). So B is incorrect.
4. Analyze Option C: As nitrates diffuse from the area of higher concentration (near the pipe) to lower concentration areas, their concentration will decrease near the pipe and increase in areas with lower initial concentration. This matches the process of diffusion.
5. Analyze Option D: Simple diffusion is a passive process and does not require energy. So D is incorrect.

Answer:

C. Nitrate concentration decreases in some places and increases in others.