Question

BOD is a measure of
A) Industrial waste being poured in the water body
B) The extent of pollution with organic compounds
C) CO combined with Haemoglobin
D) Oxygen required by green plants during the night

Answer 1

Hint: Dissolved oxygen (DO) tells about how much oxygen is dissolved in the water. Levels should not be too high or too low. It can harm aquatic life and affect water quality.

Complete Answer:
All aerobic biological compounds require dissolved oxygen. The amount of dissolved oxygen needed for breaking organic matter present in the water sample is called Biochemical oxygen demand (BOD). This can be measured at a certain temperature over a specific time.
Thus, the extent to which water is polluted with organic compounds can be measured using Biological Oxygen Demand (BOD).
The amount of dissolved oxygen in a stream or lake can tell us a lot about its water quality. The pollution of organic matter in the given water samples can also be measured with BOD. When sewage water is highly polluted, BOD will be higher.
This is due to the presence of more microbes and organic matters. So, automatically when more sewage water mixes with drinking water, the level of BOD will be higher. As a result of this, there is very less oxygen left available to higher animals like fishes. Various analytical instruments are used to measure the level of BOD. This can help to save aquatic animals and plants.

So, the correct option is B, BOD is the extent of pollution with organic compounds.

Note: The microorganisms in polluted bodies utilise dissolved oxygen to metabolise natural substances in polluted waters. This is called biochemical oxygen demand (BOD). BOD measures the amount of food that bacteria can oxidize.