Question

acid rain pollutes a lake and makes the water acidic. as a result, many aquatic plants in the lake die. how will the loss of these plants most likely affect the lake ecosystem?
a. the water will contain less oxygen and the lake will have less diversity of organisms.

b. the decomposing plants will release carbon dioxide into the water to help more plants grow.

c. the water will contain more oxygen and most of the land plants surrounding the lake will die.

d. animal populations in the lake ecosystem will increase because the decomposing aquatic plants act as fertilizer.

Explanation:

• Option A: Aquatic plants produce oxygen via photosynthesis. If they die, oxygen production decreases. Also, the loss of plants reduces habitat and food sources, decreasing organism diversity. This is consistent with ecological principles.
• Option B: Decomposing plants releasing CO₂ doesn't help new plants grow in acidic, polluted water (acid rain - damaged lake), so this is incorrect.
• Option C: Aquatic plants produce oxygen; their death would lower, not increase, oxygen levels. Also, land plants' death isn't directly caused by aquatic plants' death here, so wrong.
• Option D: Decomposing plants don't act as fertilizer to increase animal populations; loss of plants reduces food/habitat, so animal populations would likely decrease, not increase.

Answer:

A. The water will contain less oxygen and the lake will have less diversity of organisms.