Section 12 — NEET-Pattern Practice Questions (Microbes in Human Welfare)
Microbes in Human Welfare is one of the most scoring and predictable NEET chapters — you can usually expect 1 to 3 questions from it, and they are almost always straight recall of a microbe-product pairing. The questions sweep across the whole chapter: household products (curd, dough, bread, cheese), industrial products (beverages, antibiotics, organic acids, enzymes, bioactive molecules), sewage treatment and BOD, biogas and methanogens, biocontrol agents, and biofertilisers.
This section is a focused 28-question NEET-pattern practice quiz covering the entire chapter — mostly match-the-microbe-to-its-product with a few concept traps (with/without distillation, primary vs secondary treatment, nitrogen-fixers vs phosphorus-suppliers).
Important note: These are NEET-pattern practice questions built on the recurring core concepts of this chapter. Do not treat them as exact authenticated year-tagged NEET papers unless each one is separately matched against an official NEET paper and year.
How to use: Treat this like a timed mock — give yourself about 25 minutes for all 28 questions. Attempt first, then read each explanation carefully. Skim the recurring-hooks recap below to spot the question patterns before you begin.
Recurring Hooks — What NEET Loves to Ask From This Chapter
Almost every question on Microbes in Human Welfare is a microbe-product pairing. Fix these in memory:
1. Household products — curd from lactic acid bacteria (Lactobacillus), raising vitamin B12; idli/dosa dough puffed by CO2; bread from Saccharomyces cerevisiae (baker's yeast); toddy from fermented palm sap; Swiss cheese holes from Propionibacterium sharmanii (CO2); Roquefort ripened by a fungus.
2. Beverages — brewer's yeast Saccharomyces cerevisiae ferments malted cereals and fruit juices to ethanol; wine and beer = without distillation, whisky, brandy, rum = with distillation; grown in large vessels called fermentors.
3. Antibiotics — Penicillin = first antibiotic, chance discovery by Fleming from the mould Penicillium notatum, working on Staphylococci; potential established by Chain and Florey; Nobel 1945.
4. Organic acids, enzymes, bioactive molecules — citric acid: Aspergillus niger (the only fungus among acid producers); acetic acid: Acetobacter aceti; butyric acid: Clostridium butylicum; lactic acid: Lactobacillus; ethanol: Saccharomyces cerevisiae. Lipases in detergents; pectinases and proteases clarify juices. Streptokinase (Streptococcus) = clot buster; cyclosporin A (Trichoderma polysporum) = immunosuppressant; statins (Monascus purpureus) = lower cholesterol.
5. Sewage treatment — done by heterotrophic microbes naturally present; primary = physical (filtration, sedimentation → primary sludge + effluent); secondary = biological (aerobic flocs in aeration tanks reduce BOD); flocs settle as activated sludge; excess sent to anaerobic sludge digesters → biogas. Higher BOD = more polluting.
6. Biogas — predominantly methane; made by methanogens (e.g. Methanobacterium) growing anaerobically on cellulose; found in anaerobic sludge and in the rumen of cattle; dung = gobar gas; technology from IARI and KVIC.
7. Biocontrol — ladybird → aphids; dragonfly → mosquitoes; Bacillus thuringiensis (Bt) → butterfly caterpillars (toxin released in larval gut), engineered into Bt-cotton; Trichoderma → plant pathogens; baculoviruses (Nucleopolyhedrovirus) = species-specific, ideal for IPM.
8. Biofertilisers — Rhizobium (root nodules of legumes, fixes nitrogen); free-living Azospirillum, Azotobacter (fix nitrogen); Glomus → mycorrhiza, supplies phosphorus; cyanobacteria Anabaena, Nostoc, Oscillatoria fix nitrogen, important in paddy fields.