Question

Biological Oxygen Demand (BOD) is a measure of:
(A) Industrial wastes poured into water bodies.
(B) Extent to which water is polluted with organic compound
(C) Amount of carbon monoxide inseparable combined with haemoglobin
(D) Amount of oxygen needed by green plants during the night.

Answer 1

Hint: To answer this question, you must recall the meaning of BOD or the Biological oxygen demand. Dissolved oxygen in water is essential for the survival of aquatic plants and animals. The levels of the dissolved oxygen affect the quality of water and the aquatic life directly and they should not be too high or too low.

Complete step by step solution:
All aerobic biological processes require oxygen and for those occurring under water, dissolved oxygen in the water is a must. The Biochemical Oxygen Demand is the amount of the dissolved oxygen that is required by microorganisms to break down organic matter aerobically present in a given water sample. It is commonly written as BOD in short.
Thus, we can say that it tells us about the extent to which the given sample of water is polluted by organic waste material.

Hence, option B is correct.

Note:
The amount of dissolved oxygen in a water body helps us determine a lot of information about the quality of the water. When the water body is highly polluted, it has a high Biological Oxygen Demand. This is because of the presence of a higher number of microorganisms or decomposers and waste organic matter. So, on mixing with pure water, this impure water increases the BOD of the pure water as well thus, depreciating its quality. The microbes present use the dissolved oxygen for metabolizing the natural substances present in the polluted water. Thus, the oxygen available to support proper functioning of aquatic life decreases and very less oxygen is available to the aquatic organisms. Keeping a check on the BOD can help us to save many aquatic animals and plants.