NEET2010ZoologyMicrobes in Human WelfareActual
When domestic sewage mixes with river water
Options
- Asmall animals like rats will die after drinking river water
- Bthe increased microbial activity releases micronutrients such as iron
- Cthe increased microbial activity uses up dissolved oxygen
- Dthe river water is still suitable for drinking as impurities are only about 0.1 %
Correct answer
C. the increased microbial activity uses up dissolved oxygen
Step-by-step solution
Domestic sewage consists a lot of degradable organic matter. When this sewage is released into river water, it will result in an increase of Biochemical Oxygen Demand (BOD) and decrease in the amount of dissolved oxygen due to decomposing activity of microbes.