Microbes In Human Welfare

Question

Among four sewage water samples whose biochemical oxygen demand is measured, which BOD value in mg per litre indicates the most heavily polluted water?

RankGuru · Accepted Answer

Biochemical oxygen demand (BOD) measures the amount of dissolved oxygen that microorganisms consume while decomposing the organic matter present in a water sample, so a higher BOD value directly reflects a greater load of biodegradable organic pollutants. Among the given values, 200 mg/L is the largest, indicating that the microbes require a very large quantity of oxygen to break down the organic waste, which is the hallmark of heavily polluted sewage water. The value 20 mg/L represents moderately polluted water and is far lower than 200, so it is not the most polluted. A value of 8 mg/L suggests only mild organic loading, typical of partially treated or relatively clean water, and is therefore incorrect. The value 2 mg/L indicates very clean water with little organic matter, the opposite of heavy pollution. As explained in NCERT Class 12, Chapter 10 (Microbes in Human Welfare), the efficiency of sewage treatment is judged by the reduction of BOD; treated effluent has a much lower BOD than raw sewage. As a numerical sanity check, since BOD rises with pollution and 200 mg/L is the maximum value listed, it correctly represents the most heavily polluted sample.

Microbes In Human Welfare

Select the correct option:

🔒 Solution Hidden from View

More biology and human welfare Practice Questions

A bacterium widely used as a biological insecticide produces protein crystals that specifically kill...

In paddy fields, which free-living photosynthetic cyanobacterium serves as an important biofertilize...

The combustible gas produced in a biogas plant from cattle dung is generated mainly through the meta...

The first antibiotic, discovered by Alexander Fleming as a chemical that inhibited the growth of Sta...

The bacteria responsible for converting milk into curd also improve its nutritional value by increas...

Microbes grown on a large scale as an alternative protein-rich source of food for animals and humans...

A wheat variety developed through plant breeding to combat protein malnutrition by improving grain p...

The capacity of a single plant cell to regenerate into a complete plant, exploited during micropropa...

When isolated protoplasts of two different plant varieties are fused to create a hybrid such as the ...

Which controlled breeding technique allows a superior cow to yield several calves yearly by transfer...

For large-scale commercial production of honey and beeswax through apiculture, which species of hone...

Cocaine, a potent stimulant that interferes with dopamine transport in the central nervous system, i...

About This Question

Solution