Class 12 Biology - ANDHRA-PRADESH
Microbes in Human Welfare
Microbes in Human Welfare is a scoring and crucial chapter in Class 12 Biology for Andhra Pradesh (BSEAP) students. It explores how microorganisms like bacteria, fungi, viruses, and protozoa are not just disease-causing agents, but are immensely beneficial to human society. The chapter details the role of microbes in household products like curd and bread, industrial production of beverages and antibiotics, sewage treatment plants, biogas generation, and as biological control agents and biofertilizers. Mastering this chapter helps students understand applied biology, a frequent area for both objective and descriptive questions in board exams.
Start Learning FreeKey Concepts
Microbes in Household Products
Lactic Acid Bacteria (LAB) convert milk into curd, improving its nutritional quality by increasing Vitamin B12, while Saccharomyces cerevisiae (brewer's yeast) is used for fermenting dough to make bread and idli.
Microbes in Industrial Products
Microbes are grown in large vessels called fermentors to produce industrial products such as beverages (using yeast for ethanol production) and life-saving antibiotics like penicillin derived from Penicillium notatum.
Microbes in Sewage Treatment
Secondary sewage treatment relies heavily on aerobic and anaerobic microbes (flocs and methanogens) to biologically degrade organic matter in wastewater, significantly reducing its biochemical oxygen demand (BOD).
Microbes as Biocontrol Agents
Biological control refers to the use of living organisms to control plant pests and diseases, such as Bacillus thuringiensis used to kill caterpillar pests and Trichoderma used against root pathogens.
Microbes as Biofertilizers
Organisms like Rhizobium, Azospirillum, and Mycorrhiza enrich the nutrient quality of the soil by fixing atmospheric nitrogen or forming symbiotic associations with plant roots to absorb phosphorus.
Important Formulas
Board Exam Info
In the Andhra Pradesh (BSEAP) Class 12 Biology board exam, this chapter typically carries around 4 to 6 marks. Questions usually include a 2-mark short answer question (SAQ) or 4-mark very short/short answer questions focusing on sewage treatment steps, names of microbes producing specific organic acids/antibiotics, or the role of biofertilizers.
Frequently Asked Questions
What is BOD and why is it important in sewage treatment?
BOD stands for Biochemical Oxygen Demand. It measures the amount of oxygen required by bacteria to degrade organic matter in water. Higher BOD indicates high pollution, and sewage treatment aims to reduce this BOD before releasing water into natural bodies.
How do Mycorrhiza act as biofertilizers?
Mycorrhiza are symbiotic associations between fungi and roots of higher plants. The fungal symbiont absorbs phosphorus from soil and passes it to the plant, while also providing resistance to root-borne pathogens and salinity.
Which bacterium is used to produce biogas and what is the composition of biogas?
Methanogens (such as Methanobacterium) are used to produce biogas. Biogas is a mixture of methane (50-70%), carbon dioxide, and small amounts of hydrogen, hydrogen sulfide, and nitrogen.
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