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NEET2008BotanyEcosystemActual

A lake near a village suffered heavy mortality of fishes within a few days. Consider the following reasons for this (1) Lots of urea and phosphate fertilizer were used in the crops in the vicinity. (2) The area was sprayed with DDT by an aircraft. (3) The lake water turned green and stinky. (4) Phytoplankton populations in the lake declined initially thereby greatly reducing photosynthesis. Which two of above were th

Options

  1. A2,3
  2. B3,4
  3. C1,3
  4. D1,2

Correct answer

C. 1,3

Step-by-step solution

The heavy mortality of fishes in the lake within a span of few days is due to Eutrophication. Eutrophication is the phenomenon of nutrient enrichment of nitrogen and phosphorus in a water body that supports a dense growth of plants and animal life. Due to nutrient enrichment, excess growth of algae occurs which is called algal bloom. When these algae die, their organic matter gets decomposed and this results in the depletion of oxygen leading to death of aquatic animals. Hence, this indicates that lot of urea and p

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