Which sequence correctly describes eutrophication of a lake?
Answer and explanation
Correct answer: D. Fertiliser runoff, algal bloom, light blocked, plants die, decomposer growth, oxygen falls
- Step 1: Nitrates and phosphates promote algal growth. Step 2. Algae block light and plants die, decomposers multiply and use up oxygen, and fish die. Answer: Fertiliser runoff, algal bloom, light blocked, plants die, decomposer growth, oxygen falls. Why not the others: oxygen falls rather than rises; decomposers increase, not decrease; acid rain is not the cause.
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