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CBSE Questions for Class 12 Medical Biology Microbes In Human Welfare Quiz 12 - MCQExams.com
CBSE
Class 12 Medical Biology
Microbes In Human Welfare
Quiz 12
Cellulases and hemicellulases arc in great demand nowadays for the preparation of second-generation:
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biodiesel
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bioplastics
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bioethanol
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antibiotics
Explanation
Lignocellulose, a major component of plant biomass produced through photosynthesis, is abundant, sustainable and renewable. Therefore, it is no surprise that lignocellulosic bioenergy has become a subject of intense investigation. In comparison to fossil fuels, lignocellulosic biofuel offers many advantages: it is renewable and environmentally friendly; it has potential to mitigate global warming; it can prevent a fuel shortage and it has no effect in the food chain. One of the processes studied for obtaining the highest potential of sugars for the production of biofuel is the enzymatic hydrolysis of lignocellulosic wastes, using cellulases and hemicellulases.
So, the correct answer is 'biodiesel'.
Which one of the following is wrong statement?
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Anabaena
and
Nostoc
are capable of fixing nitrogen in free living state also.
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Root nodule forming nitrogen fixers live as aerobes under free living conditions.
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Phosphorus is a constituent of cell membranes, certain nucleic acids and all proteins.
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Nitrosomonas
and
Nitrobacter
are chemoautotrophs.
Explanation
Anabaena
and
Nostoc
are also free-living nitrogen fixers.
Root nodule forming nitrogen fixers enzyme (nitrogenase) works only under the anaerobic condition.
Phosphorus is a constituent of cell membranes as a phospholipid, in nucleic acid as phosphate group and proteins are rich in phosphorus.
Nitrosomonas
and
Nitrobacter
play an important role in nitrification. They are chemoautotrophs.
So the correct answer is 'Root nodule forming nitrogen fixers live as aerobes under free-living conditions'.
The microbial biofertilizers which can act both symbiotically and non-symbiotically to increases soil fertility are?
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Azotobacter
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Rhizobium
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Clostridium
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Nostoc and Anabaena
Explanation
Azobacter is a free-living nitrogen-fixing bacterium, which is used as a biofertilizer is the cultivation of most crops. Azobacter is usually motile, oval, or spherical bacteria, form thick-walled cysts and may produce large quantities of capsular time.
So, the correct option is 'Azobacter'.
Sewage treatment process includes all of these features, except
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A small part of the activate sludge is pumped back into the aeration tank to serve as incoculum
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Activated sludge cannot be used in anaerobic digestion process
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Anaerobic bacteria digest aerobic bacteria in sludge digesters
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Transfer of primary effluent in aeration tanks
Explanation
The process of removal and digestion of inorganic and organic waste present in the sewage water is called sewage treatment.
A. The flocs of bacteria obtained after treatment of the sewage water is called activated sludge. A small part of it is pumped back into the aeration tank which will act as inoculum and will multiply to start the digestion of organic compounds again.
B. Activated sludge can be anaerobic bacterium as well.
C. In sludge digesters, the digestion of organic compounds occurs.
D. Primary effluent is transferred to the aeration tanks for the purpose of digestion through aerobic bacteria.
Hence, the correct answer is 'Anaerobic bacteria digest aerobic bacteria in sludge digesters'.
Refer to the given dichotomous key and select the correct option.
I. (a) Fibre obtained from natural sources - Go to II
(b) Fibre obtained from chemical, - K
II. (a) It is a cellulosic fibre - Go to III
(b) It is a protein fibre. - Go to IV
III. (a) It is obtained from leaves. - L
(b) It is obtained from seeds.
IV. (a) It is obtained from mammals. - N
(b) It is obtained from an insect. - O
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Fabrics fibres K and N could be water proof.
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When fibres L and M are burnt separately they give smell of burning paper and burning hair, respectively.
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Fibre L is separated from leaves by retting process whereas from seeds by ginning process.
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N can be obtained from the same animal repeatedly whereas O can be obtained from source animal only once in its lifetime.
Explanation
Fabrics fibers K and N are usually laminated to or coated with a waterproofing material such as rubber, polyvinyl chloride (PVC), polyurethane (PU), silicone elastomer, fluoropolymers, and wax
So, the correct option is 'Fabrics fibers K and N could be waterproof'.
Match the following columns and select the correct option.
Column-I
Column-II
(a)
Clostridium butylicum
(i)
Cyclosporin-A
(b)
Trichoderma polysporum
(ii)
Butyric Acid
(c)
Monascus purpureus
(iii)
Citric Acid
(d)
Aspergillus niger
(iv)
Blood cholesterol-lowering agent
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(a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
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(a)-(i), (b)-(ii), (c)-(iv), (d)-(iii)
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(a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
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(a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)
Explanation
Clostridium butylicum
- is used in the production of Butyric acid.
Trichoderma polysporum
- is used in the production of Cyclosporin-A and C, an antifungal antibiotic.
Monascus purpureus -
is used in the production of statin which helps in lowering blood cholesterol.
Aspergillus niger
- helps in the production of Citric acid.
Thus, the correct answer is (A).
Wine and beer are produced directly by fermentation whereas brandy and whisky require both fermentation and distillation. This is because?
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Fermentation is inhibited at an alcohol level of $$10-18\%$$
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Distillation prolongs storage
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Distillation improves quality
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Distillation purifies the beverage
The flour of idli and dosa is made by the use of which microbe?
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Saccharomyces
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Lactobacillus
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Aspergillus
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Both A and B
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