Class XII · Biology practice
Microbes in Human Welfare MCQs
Check your understanding, bookmark questions and revisit your mistakes.
455 questions in this collection · Page 27 of 46
Question 261 of 455
📘 CLASS XII
Microbes In Human Welfare
The treatment of waste water in STPs is carried out by _____ microbes naturally present in the sewage.
Treatment of waste water is done by the heterotrophic microbes naturally present in the sewage.
Question 262 of 455
📘 CLASS XII
Microbes In Human Welfare
Primary sewage treatment involves the physical removal of particles through filtration and _____.
Primary treatment involves physical removal of particles through filtration and sedimentation.
Question 263 of 455
📘 CLASS XII
Microbes In Human Welfare
In primary treatment, floating debris is removed by sequential _____.
Initially, floating debris is removed by sequential filtration.
Question 264 of 455
📘 CLASS XII
Microbes In Human Welfare
All solids that settle during primary treatment form the _____, and the supernatant forms the effluent.
All solids that settle form the primary sludge.
Question 265 of 455
📘 CLASS XII
Microbes In Human Welfare
Secondary treatment of sewage is also known as _____ treatment.
Secondary treatment or Biological treatment.
Question 266 of 455
📘 CLASS XII
Microbes In Human Welfare
During secondary treatment, the primary effluent is passed into large _____ tanks where air is pumped in.
The primary effluent is passed into large aeration tanks where it is constantly agitated mechanically and air is pumped into it.
Question 267 of 455
📘 CLASS XII
Microbes In Human Welfare
In aeration tanks, useful aerobic microbes grow into mesh-like structures called _____.
Useful aerobic microbes grow into flocs (masses of bacteria associated with fungal filaments to form mesh like structures).
Question 268 of 455
📘 CLASS XII
Microbes In Human Welfare
The growth of flocs in the aeration tank significantly reduces the _____ (BOD) of the effluent.
This significantly reduces the BOD (biochemical oxygen demand) of the effluent.
Question 269 of 455
📘 CLASS XII
Microbes In Human Welfare
BOD is indirectly a measure of the amount of _____ present in the water.
BOD is a measure of the organic matter present in the water.
Question 270 of 455
📘 CLASS XII
Microbes In Human Welfare
After BOD reduction, the sedimented bacterial flocs in the settling tank form the _____.
The bacterial ‘flocs’ are allowed to sediment in a settling tank where they form the activated sludge.
Page score: 0/40