Question

BOD of a pond is related to ______ in per unit volume of water.
A) All the plants
B) All the nektons
C) All the microbes
D) All the animals

Answer 1

We have observed many times some of the ponds start smelling and show different colours. This is due to the reduction in the oxygen level of the pond the aquatic organisms find it difficult to survive and it is related to the BOD of the water bodies.

Complete answer:
To answer this question, we first understand about the BOD of water. BOD stands for biological oxygen demand, it represents the amount of oxygen used by the microorganisms while decomposing organic matter under certain temperature in aerobic condition. The water comprises a certain amount of dissolved oxygen that is being used by the aquatic organisms to survive. The presence of sufficient amounts of dissolved oxygen is very important for aquatic life forms and it is very critical to maintain the aesthetic quality of lakes and streams. The decay organic matter inside the water bodies is measured as the chemical oxygen demand and the oxygen demand is measured by the oxidized substance in the water sample that lowers the DO concentration of water. The higher BOD indicates the requirement of higher oxygen and signifies the low quality of water. Less BOD means less oxygen is being removed from water and the water is considered to be pure.
Now, the BOD of a pond is related to all the microbes in per unit volume of water. The aerobic microorganisms break-down the organic materials found in a given sample of pond water at a certain temperature for a specific time period and that is the BOD of the per unit volume of the sample.

Thus, the correct answer is option ‘C’. All the microbes.

Note: The chemical oxygen demand is the presence of inert organic matters in a given sample of water. It is measured as the total amount of oxygen required to oxidize the organic matter into water and carbon dioxide. The COD value is greater than the BOD values.