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WAEC Biology 2005 Question 45

Question 45

Pollution

Algal bloom depletes oxygen content of bodies of water polluted by

  1. A.industrial effluents
  2. B.thermal plant discharge
  3. C.raw sewage disposal
  4. D.crude oil spillage
Show the answer and explanation

Answer: C (raw sewage disposal)

Explanation

Raw sewage adds nitrates and phosphates that make algae grow rapidly; when they die, decomposers use up the oxygen in the water.