Class XII · Biology practice
Microbes in Human Welfare MCQs
Check your understanding, bookmark questions and revisit your mistakes.
455 questions in this collection · Page 3 of 46
Question 21 of 455
📘 CLASS XII
Microbes In Human Welfare
In primary treatment, all solids that settle during sedimentation form the:
All solids that settle form the primary sludge, and the supernatant forms the effluent.
Question 22 of 455
📘 CLASS XII
Microbes In Human Welfare
The secondary treatment of sewage is also known as:
Secondary treatment is also called Biological treatment.
Question 23 of 455
📘 CLASS XII
Microbes In Human Welfare
During secondary treatment in aeration tanks, vigorous growth of useful aerobic microbes form mesh-like structures called:
Aerobic microbes grow into flocs (masses of bacteria associated with fungal filaments to form mesh like structures).
Question 24 of 455
📘 CLASS XII
Microbes In Human Welfare
The growth of flocs in the aeration tank significantly reduces the BOD of the effluent. What does BOD stand for?
The growth of microbes significantly reduces the BOD (biochemical oxygen demand) of the effluent.
Question 25 of 455
📘 CLASS XII
Microbes In Human Welfare
The greater the BOD of waste water, the greater is its:
The greater the BOD of waste water, more is its polluting potential.
Question 26 of 455
📘 CLASS XII
Microbes In Human Welfare
In the settling tank after aeration, the bacterial flocs sediment to form:
The bacterial ‘flocs’ are allowed to sediment in a settling tank, forming the activated sludge.
Question 27 of 455
📘 CLASS XII
Microbes In Human Welfare
A small part of the activated sludge is pumped back into the aeration tank to function as the:
A small part of the activated sludge is pumped back into the aeration tank to serve as the inoculum.
Question 28 of 455
📘 CLASS XII
Microbes In Human Welfare
The remaining major part of the activated sludge is pumped into large tanks for anaerobic digestion, called:
The remaining major part of the sludge is pumped into large tanks called anaerobic sludge digesters.
Question 29 of 455
📘 CLASS XII
Microbes In Human Welfare
The digestion of bacteria and fungi in the anaerobic sludge digesters produces a mixture of gases including:
During digestion, bacteria produce a mixture of gases such as methane, hydrogen sulphide and carbon dioxide.
Question 30 of 455
📘 CLASS XII
Microbes In Human Welfare
Which ministry initiated the Ganga Action Plan and Yamuna Action Plan to save major rivers from pollution?
The Ministry of Environment and Forests has initiated Ganga Action Plan and Yamuna Action Plan.
Page score: 0/40