NEET Biology Microbes in Human Welfare MCQs Set 15

Answer: (a) A-Streptokinase; B-Myocardial infarction

Explanation:
1. A-Streptokinase; B-Myocardial infraction
2. Hence option (a) is correct: A-Streptokinase; B-Myocardial infarction

Teacher's Note:
1. Streptokinase is a clot buster used after a myocardial infarction.
2. It is produced by Streptococcus and modified by recombinant techniques.

Answer: (a) Citric acid – Aspergillus flavus

Explanation:
1. Citric acid – Aspergillus niger Afflatoxin – Aspergillus flavus
2. Hence option (a) is correct: Citric acid – Aspergillus flavus

Teacher's Note:
1. Aspergillus niger produces citric acid while A. flavus produces aflatoxin.
2. Match each microbe with its product carefully.

Answer: (b) Penicillin

Explanation:
1. Penicillin is obtained from Penicillium notatum fungus.
2. Hence option (b) is correct: Penicillin

Teacher's Note:
1. Penicillin from Penicillium notatum was used to treat wounded soldiers in World War II.
2. Fleming discovered it and Chain and Florey purified it.

Answer: (b) Decreases oxygen content of water

Explanation:
1. The greater BOD of waste water indicates decrease oxygen content of water.
2. Hence option (b) is correct: Decreases oxygen content of water

Teacher's Note:
1. High BOD means a lot of organic matter and heavy microbial oxygen use, so dissolved oxygen falls.
2. BOD is a measure of pollution load.

Answer: (a) 1985

Explanation:
1. Ganga Action Plan for controlling pollution in Ganges, was started in 1985.
2. Hence option (a) is correct: 1985

Teacher's Note:
1. The Ganga Action Plan began in 1985.
2. It aimed at sewage interception and treatment.

Answer: (d) Involves microbial digestion of organic matter

Explanation:
1. Secondary treatment of sewage involves microbial digestion of organic matter.
2. Hence option (d) is correct: Involves microbial digestion of organic matter

Teacher's Note:
1. Secondary (biological) treatment uses aerobic microbes to digest organic matter in the aeration tank.
2. Primary treatment is physical.

Answer: (a) Primary treatment

Explanation:
1. The removal of floating and suspended solids from sewage through filtration and sedimentation is the part of primary treatment of sewage.
2. Hence option (a) is correct: Primary treatment

Teacher's Note:
1. Primary treatment removes floating and suspended solids by filtration and sedimentation.
2. It is a physical process.

Answer: (c) 50% – 70% Methane

Explanation:
1. Biogas contains CH₄ – 50-70% CO₂ – 30-40% H2, H₂S etc – 10%
2. Hence option (c) is correct: 50% – 70% Methane

Teacher's Note:
1. Biogas is mostly methane (50 to 70 percent) with CO2 and small amounts of H2 and H2S.
2. Methane makes it a fuel.

Answer: (d) (a), (b), (c) & (d)

Explanation:
1. All are natural insecticides.
2. Hence option (d) is correct: (a), (b), (c) & (d)

Teacher's Note:
1. Rotenone, pyrethrum, nicotine and azadirachtin are all plant derived insecticides.
2. Natural insecticides are safer than synthetic ones.

Answer: (a) Blue-green algae, Rhizobium, other nitrogen-fixing bacteria and mycorrhiza

Explanation:
1. Biofertilisers include Blue-green algae, Rhizobium, other nitrogen-fixing bacteria and mycorrhiza.
2. Hence option (a) is correct: Blue-green algae, Rhizobium, other nitrogen-fixing bacteria and mycorrhiza

Teacher's Note:
1. Biofertilisers include cyanobacteria, Rhizobium, other nitrogen fixers and mycorrhiza.
2. NPV and Bt are biopesticides.

Answer: (d) Vitamin B₁₂

Explanation:
1.  Curd is more nourishing than milk.  It has enriched presence of vitamins specially Vit-B₁₂.
2. Hence option (d) is correct: Vitamin B₁₂

Teacher's Note:
1. Conversion of milk to curd by lactic acid bacteria increases vitamin B12.
2. It also improves digestibility.

Answer: (c) Primary treatment

Explanation:
1. Primary treatment is a physical process which involves sequential filtration and sedimentation.
2. Hence option (c) is correct: Primary treatment

Teacher's Note:
1. Primary treatment removes suspended solids physically by sequential filtration and sedimentation.
2. Biological treatment follows it.

Answer: (d) Aspergillus

Explanation:
1. Citric acid – Aspergillus niger.
2. Hence option (d) is correct: Aspergillus

Teacher's Note:
1. Aspergillus niger is the commercial source of citric acid.
2. Lactobacillus gives lactic acid and Acetobacter gives acetic acid.

Answer: (b) Methane

Explanation:
1. In gobar gas, maximum amount is Methane (CH₄).
2. Hence option (b) is correct: Methane

Teacher's Note:
1. Gobar gas contains mainly methane, produced by methanogens.
2. CO2 is the second component.

Answer: (d) Anabaena

Explanation:
1. Anabaena azollae associated with Azolla (fern).
2. Hence option (d) is correct: Anabaena

Teacher's Note:
1. Anabaena azollae lives in leaf cavities of the water fern Azolla and fixes nitrogen.
2. This is useful in rice fields.

Answer: (a) Clostridium butylicum - lactic acid

Explanation:
1. Clostridium butylicum - Butyric acid.
2. Hence option (a) is correct: Clostridium butylicum - lactic acid

Teacher's Note:
1. Clostridium butylicum produces butyric acid, not lactic acid.
2. Lactic acid comes from Lactobacillus.

Answer: (c) Alcohol - nitrogenase

Explanation:
1. Hence option (c) is correct: Alcohol - nitrogenase

Teacher's Note:
1. Zymase is the yeast enzyme complex for alcohol production.
2. Nitrogenase is the nitrogen fixing enzyme.

Answer: (b) Lignin

Explanation:
1. During anaerobic digestion of organic waste, such as producing biogas undegraded Lignin is remain.
2. Hence option (b) is correct: Lignin

Teacher's Note:
1. Lignin is not degraded during anaerobic digestion because microbes cannot break it down easily.
2. Cellulose and hemicellulose are degraded.

Answer: (d) Spirogyra

Explanation:
1. Spirogyra is alga is not nitrogen-fixer.
2. Hence option (d) is correct: Spirogyra

Teacher's Note:
1. Spirogyra is a green alga that cannot fix atmospheric nitrogen.
2. Azotobacter, Anabaena and Nostoc are nitrogen fixers.

Answer: (b) Glomus

Explanation:
1. Glomus absorbs phosphorus from soil by plants as mycorrhiza.
2. Hence option (b) is correct: Glomus

Teacher's Note:
1. Mycorrhizal fungi such as Glomus increase phosphorus absorption by plants.
2. They also improve water uptake.