Microbes in Human Welfare

Microbes in Human Welfare is one of the shortest and most scoring chapters of Class 12 Biology — almost entirely factual, with a steady 2-3 NEET questions every year and a reliable CBSE short-answer or 3-mark question on sewage treatment or biocontrol. The whole chapter is a catalogue of the useful side of microbes, organised around six themes: microbes in household products (curd, dough, cheese), industrial products (fermented beverages, antibiotics, and a long list of chemicals, enzymes and bioactive molecules), sewage treatment (primary and secondary treatment, flocs, BOD, activated sludge), biogas production (methanogens and the gobar-gas plant), biocontrol agents (Bt, Trichoderma, baculoviruses, ladybird and dragonfly), and biofertilisers (Rhizobium, Azotobacter, mycorrhiza and cyanobacteria). Success here is almost pure recall — the exact microbe paired with its exact product — so the chapter rewards a clean, well-organised set of association tables. By the end you should be able to name the organism behind every product, explain how a sewage treatment plant lowers BOD, and argue why biofertilisers and biocontrol beat chemical fertilisers and pesticides.