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Biology · 2022 · 2 marks
CBSE 2022 · Region 1 · Set 1 · Q2
State the impact of constant mechanical agitation and pumping of air in the aeration tank on the sewage during the biological treatment.
State the impact of constant mechanical agitation and pumping of air in the aeration tank on the sewage during the biological treatment.
OR
(a)
Cattle excreta is important source for producing a domestic fuel. Name the fuel and write its main components.
(b)
Write the biological process that is responsible for the production of this fuel.
Marking-scheme solution
Allows vigorous growth of microbes, formation of flocs to form mesh like structures, microbes consume major part of organic waste in the sewage, reduces BOD of the affluent / reduces polluting potential
OR
(a)
Biogas / Gobar gas
Methane, \(\displaystyle \mathrm{CO}_{2} / \mathrm{H}_{2} / \mathrm{H}_{2} \mathrm{~S}\)
(b)
Anaerobic digestion of cellulose
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CBSE Class 12 Biology past-paper question from the 2022 board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.