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WAEC Biology 2014 Objective — Question 36

Question 36 of 50 from the West African Examinations Council (WAEC) Biology 2014 Objective paper, with the correct answer and a full explanation.

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The table shows the oxygen level, number of green plants and fish in rivers flowing through four towns. Which of the towns is likely to be discharging untreated sewage in their river?

  • A. Town A
  • B. Town B
  • C. Town C
  • D. Town DCorrect

Explanation

The discharge of untreated sewage into a water body causes a decrease in the oxygen level of the water, because the bacteria that decompose the sewage feast on oxygen, reducing the population of aquatic animals like fish. Town D shows low oxygen, many green plants, and few fish — consistent with untreated sewage discharge.

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