Class 12 Biology - HARYANA
Microbes in Human Welfare
Microbes in Human Welfare is a scoring and crucial chapter in Class 12 Biology under the Haryana Board (BSEH) curriculum. It explores the diverse roles microorganisms play in enhancing human life, moving beyond disease-causing pathogens to beneficial applications. Students will learn about household products like curd and bread, industrial production of beverages and antibiotics, sewage treatment plants, the use of microbes as biofertilisers and biocontrol agents, and biogas production. Understanding these concepts is vital for board exams, as questions frequently appear on specific microbial strains, their products, and their ecological significance.
Start Learning FreeKey Concepts
Microbes in Household Products
Microorganisms like Lactobacillus (LAB) convert milk to curd by producing acids that coagulate milk proteins, while Saccharomyces cerevisiae (brewer's yeast) is used to ferment dough for foods like idli, dosa, and bread.
Microbes in Industrial Production
Industrially, microbes are grown in large vessels called fermentors to produce beverages like wine and beer using yeast, and life-saving antibiotics such as penicillin produced by the fungus Penicillium notatum.
Microbes in Sewage Treatment
Municipal wastewater is treated in Sewage Treatment Plants (STPs) using aerobic and anaerobic microbes in primary and secondary treatment stages to reduce biological oxygen demand (BOD) before releasing water into natural water bodies.
Microbes as Biocontrol Agents
Microbes are used to control plant pests and diseases naturally without harmful chemicals; for example, the bacterium Bacillus thuringiensis is used to control butterfly caterpillars.
Microbes as Biofertilisers
Biofertilisers are organisms that enrich the nutrient quality of the soil. Examples include Rhizobium in root nodules of legumes, Azospirillum, Azotobacter, and mycorrhizal fungi that absorb phosphorus.
Important Formulas
Board Exam Info
In the Haryana Board (BSEH) Class 12 Biology examination, this chapter typically carries around 3 to 4 marks. Questions generally include objective (MCQs), very short answer questions asking for specific microbe-product pairs, and 2-3 mark questions on sewage treatment or biofertilisers.
Frequently Asked Questions
Which bacterium is commonly used to convert milk into curd?
Lactic Acid Bacteria (LAB), such as Lactobacillus, are used to convert milk into curd.
What is BOD and why is it important in sewage treatment?
BOD stands for Biological Oxygen Demand. It measures the amount of oxygen required by microbes to decompose organic matter in water. Higher BOD indicates higher organic pollution.
How do mycorrhiza help plants?
Mycorrhiza are symbiotic associations between fungi and plant roots. The fungal symbiont absorbs phosphorus from soil and passes it to the plant, while also providing resistance to root-borne pathogens and drought.
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