CBSE Class 12 Biology Revision Notes Chapter 10 - Microbes In Human Welfare
REVISION NOTES FOR CBSE CLASS 12 BIOLOGY CHAPTER 10
CHAPTER 10. MICROBES IN HUMAN WELFARE
In household food processing, industrial production, sewage treatment, energy generation and microbes as biocontrol agents and biofertilizers; Antibiotics; production and judicious use.
Biofertilisers: Microorganisms which produce fertilisers and enrich the soil e.g., bacteria, cyanobacteria and fungi.
Bioactive Molecules: Molecules produced for commercial use from microbes and used for various purposes e. g., Trichoderma polysporum (fungus) is used to obtain immunosuppressive agent cyclosporin-A.
Biochemical Oxygen Demand (BOD): Total amount of oxygen consumed by bacteria for oxidation of organic matter present in one litre of water.
Baculovirus: Pathogens that attack insects and other arthropods. They are used to kill harmful pests and arthropods e.g., Nucleopolyhedrovirus.
Flocs: During secondary treatment of effluent, excessive growth of aerobic bacteria and fungi form a mass of mesh like structure called flocs.
Immunosuppressive Agent: Chemicals which suppress the immunity against organ transplant.
Organic Farming: Technique of farming, in which biofertilisers are used to enrich the soil, without using chemical fertilisers and pesticides to reduce their harmful effect on human health.
Biological Control: Reduction of pest population by natural enemies minimising the use of harmful chemical pesticide. e.g. ladybird beetle can eradicate aphids.
Thermal vents: The sites deep inside the geysers/hot springs and oceans where the average temperature is as high as 100°C.
Methanogens: Bacteria producing large quantity of methane during decomposition of organic matter.
GAP- Ganga Action Plan
KVIC- Khadi and Village Industries Commission
TMVT- obacco Mosaic Virus Yamuna Action Plan
YAP- Yamuna Action Plan
IPM- Integrated Pest Management
¶ Microbes includes protozoa, bacteria, fungi, microscopic plants, viruses, viroids and prions (the infectious protein)
MICROBES IN HOUSEHOLD PRODUCTS
MICROBES IN PRODUCTION OF BIOGAS
¶ Some bacteria which grow anacrobically on cellulosic material produce large amount of Methane (CH₂), along with Carbondioxide and hydrogen. These bacteria are called methanogens.
¶ Methanogen are naturally found in rumen of cattle, Cowdung and sewage.
MICROBES AS BIOCONTROL AGENTS
MICROBES AS BIOFERTILISERS.
¶ Rhizobium: Have symbiotic association with roots of leguminous plants, help in atmospheric nitrogen fixation.
¶ Azospirillum and Azotobacter: Free living in soil and help in nitrogen 2-fixation enrich nitrogen 2-content of soil.
¶ Micorrhiza: Symbiotic; association of fungi with roots of higher plants. Fungi help in absorption of phosphorous from soil. It belongs to genus Glomus It provides resistance to root borne pathogens, tolerance to salinity and drought.
Cyanobacteria : Found in aquatic or terrestrial environment, help in nitrogen fixation, add organic matter to the soil, increase fertility of soil, e.g., Nostoc, Anabaena, Oscillatoria. In paddy fields, these acts as biofertilisers.
MICROBES IN INDUSTRIES
(a) Fermented Beverages Liquid food made by anaerobic digestion of carbohydrate rich food is called beverage. Saccharomyces cerevisae (yeast) is also used to make bread, fermented fruit juice and alcohol.
(b) Antibioitics: Penicillium notatum
(c) Other chemicals/enzymes/Bioactive molecules Many organic acids, enzymes are also produced by microorganisms.
SEWAGE TREATMENT:
Penicillin, First antibiotic discovered by Alexander Flemming from fungus Penicillium notatum.
MODE OF ACTION OF ANTIBIOTICS
(1) Bacteriocidal: To kill bacteria by stopping cell wall formation
(2) Bacterio-static : To stop growth or multiplication of bacteria by stapping DNA replication or other cellular metabolism.
Production of Antibiotics: Mass production of antibiotics is done in fermentor tanks from lichens, fungi, actinomycetes, eubacteria etc. Maximum antibiotics are produced from bacillus (eubacteria)
PRECAUTIONS IN TAKING ANTIBOTICS :
¶ Keep intake continuous as prescribed by doctor till course gets completed.
¶ Avoid over use otherwise our body become resistant to antibiotics.
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