Questions
3 MCQs per paper
Difficulty
Easy
Importance
High yield, easy marks for NEET and Boards
Overview
Microbes in Human Welfare focuses on the diverse applications of microorganisms in industrial, agricultural, and domestic sectors. It is a high-scoring NCERT-centric topic that frequently tests factual recall of specific microbial species and their respective metabolic products. Mastering this requires memorising the specific roles of bacteria, fungi, and viruses in biotechnology and environmental remediation.
Microbes in Household and Industrial Products
Microbes are utilised for fermentation processes to produce staple foods and large-scale industrial chemicals. Key focus areas include the specific strains used for organic acid production and enzyme synthesis.
- Lactic Acid Bacteria (LAB) convert milk to curd and improve nutritional quality via Vitamin B12
- Saccharomyces cerevisiae (Brewer's yeast) for ethanol production
- Aspergillus niger produces Citric acid
- Acetobacter aceti produces Acetic acid
- Clostridium butylicum produces Butyric acid
Antibiotics and Chemicals
Antibiotics are chemical substances produced by microbes that inhibit or kill other disease-causing microorganisms. Understanding the historical context and biological sources is critical for exam success.
- Penicillin: First antibiotic discovered by Alexander Fleming from Penicillium notatum
- Streptokinase: Used as a 'clot buster' for myocardial infarction patients
- Cyclosporin A: Immunosuppressive agent produced by Trichoderma polysporum
- Statins: Blood-cholesterol lowering agents produced by Monascus purpureus
Sewage Treatment and Biogas
Microbes play a vital role in cleaning wastewater and producing sustainable energy via anaerobic digestion. Questions often target the distinction between Primary and Secondary treatment processes.
- Primary Treatment: Physical removal of particles through filtration and sedimentation
- Secondary Treatment: Biological treatment using aerobic microbes forming flocs
- BOD (Biochemical Oxygen Demand) measures organic matter; higher BOD indicates more pollution
- Methanogens (e.g., Methanobacterium) grow anaerobically to produce biogas (CH4, CO2, H2)
- Activated sludge is used as an inoculum for the aeration tank
Biocontrol and Biofertilisers
Biological control agents reduce the dependence on toxic chemical pesticides. Biofertilisers are organisms that enrich the nutrient quality of soil, primarily through nitrogen fixation.
- Bacillus thuringiensis (Bt): Used as a biocontrol for butterfly caterpillars
- Trichoderma: Free-living fungi used for plant pathogen control
- Baculoviruses (Nucleopolyhedrovirus): Narrow-spectrum species-specific insecticides
- Rhizobium: Symbiotic N2 fixation in leguminous plants
- Cyanobacteria (Anabaena/Nostoc): Key biofertilisers in paddy fields
Exam Tip
Create a table mapping each microbe to its respective product or function, as nearly all exam questions are direct 'match the following' or 'select the correct pair' style.
Common Mistakes
- Confusing the specific microbe with the product, especially between Streptokinase and Statins.
- Assuming BOD is proportional to water purity; remember that higher BOD equals lower water quality.
- Misidentifying the type of organism (e.g., classifying a fungus as a bacterium).
More Revision Notes
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