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Environmental Issues — BIOLOGY STD 12 Science — Question

Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYEnvironmental Issues3 Marks
Question
Study the graph given below and answer the questions that follow:
  1. What is the relationship between dissolved oxygen and biochemical oxygen demand (BOD)?
  2. Mention their effect on aquatic life in the river.
✓

Answer

  1. As the BOD increases, the amount of dissolved oxygen in the water body decreases sharply from the point of sewage discharge.
  2. This causes mortality of fish and other aquatic organisms. Excess presence of nutrients in the water causes algal bloom, which also causes fish mortality.

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