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The lake became polluted because a farmer used a lot of fertiliser on his crops - Edexcel - GCSE Biology - Question 6 - 2014 - Paper 1
Question 6
The lake became polluted because a farmer used a lot of fertiliser on his crops. Complete the sentence by putting a cross (X) in the box next to your answer. The p... show full transcript
Worked Solution & Example Answer:The lake became polluted because a farmer used a lot of fertiliser on his crops - Edexcel - GCSE Biology - Question 6 - 2014 - Paper 1
Step 1
Step 2
Explain why the overuse of fertiliser by the farmer caused the fish in the lake to die.
Answer
The overuse of fertiliser leads to increased nutrients, particularly nitrogen and phosphorus, entering the lake. This causes a process known as eutrophication, where excessive nutrients promote the rapid growth of algae, known as algal blooms.
When these algae die, they decompose, a process that consumes significant amounts of oxygen in the water. The depletion of oxygen creates hypoxic conditions, making it difficult for fish and other aquatic organisms to survive. As a result, the fish population may die off due to lack of oxygen, leading to a disturbed aquatic ecosystem.