Question

B.O.D is connected with
(a)Organic matter
(b)Microbes
(c)Microbes and organic matter
(d)None of the above

Answer 1

Hint: These are a microscopic organism that exists as unicellular, multicellular, or cell clusters, the other is carbon-based compounds.

Complete answer:
Biological oxygen demand or BOD is the amount of oxygen required by microbes to break down the organic matter available in a particular volume of a sample of water. The measure of the amount of organic material in the water is the amount of BOD in the water. BOD is high in polluted water as it contains plenty of organisms. Water has the highest potential to hold oxygen which enters the water through diffusion. The high temperature, hazardous waste, and untreated sewage having biotoxins can reduce the oxygen to an alarming level leading to the suffering of fishes and other aquatic organisms which may lead to death. This is due to the fact that untreated sewage water is rich in microbes and organic matter which utilize the dissolved oxygen for the decomposition.
There are two recognized methods for the measurement of dissolved oxygen for BOD and they are dilution and the other manometric method. There are many other methods not currently internationally recognized as standard methods.
So, the correct answer is 'Microbes and organic matter'.

Note: Daphnia, a genus of small planktonic crustaceans are small organisms (0.2–5 millimeters in length) which are sensitive to pollutants. They are one of the several small aquatic crustaceans and their swimming style resembles the movements of fleas so they are commonly known as water fleas. The more pollutants in the water the lesser these organisms in the water so they are used as bioindicators for water pollution.