Class 12 Biology - CBSE
Microbes in Human Welfare
Microbes in Human Welfare explores the beneficial roles of microorganisms in our daily lives and industrial processes. Class 12 CBSE students learn how bacteria, fungi, and viruses are utilized in household product production, industrial alcohol and antibiotic manufacturing, sewage treatment, pest control as biocontrol agents, and as biofertilizers. Understanding these applications is crucial for appreciating biotechnology's scope. For board exams, this chapter is a high-scoring, fact-based unit where questions frequently focus on specific scientific names of microbes, their commercial products, and their ecological significance.
Start Learning FreeKey Concepts
Microbes in Household Products
Microorganisms like Lactobacillus convert milk into curd by producing lactic acid, while Saccharomyces cerevisiae (brewer's yeast) is used to ferment dough for idli, dosa, and bread.
Microbes in Industrial Products
Industrially, microbes are grown in large vessels called fermenters to produce beverages, antibiotics (e.g., penicillin from Penicillium notatum), and organic acids like citric acid and acetic acid.
Microbes in Sewage Treatment
Primary and secondary (biological) sewage treatment uses aerobic and anaerobic microbes to reduce biochemical oxygen demand (BOD) and produce biogas in anaerobic sludge digesters.
Microbes as Biocontrol Agents
Biological control involves using natural predators and pathogens to control plant pests and diseases, such as Bacillus thuringiensis used to control caterpillar pests.
Microbes as Biofertilizers
Organisms like Rhizobium, Azospirillum, and Mycorrhiza enrich the nutrient quality of the soil by fixing atmospheric nitrogen and forming symbiotic associations with plant roots.
Important Formulas
Board Exam Info
In the CBSE Class 12 Biology board exam, this chapter typically carries around 3 to 4 marks. Questions are usually direct and include 1-mark objective questions, 2-mark or 3-mark short-answer questions asking for specific microbe names and their commercial products, matching columns, or diagram-based questions from the biogas plant.
Frequently Asked Questions
What are statins and which microbe produces them?
Statins are blood-cholesterol lowering agents produced by the yeast Monascus purpureus.
How does Mycorrhiza help plants?
Mycorrhiza is a symbiotic association between fungi and roots of higher plants. The fungal symbiont absorbs phosphorus from soil and passes it to the plant, also providing resistance to root-borne pathogens and tolerance to salinity and drought.
Why is secondary treatment of sewage also called biological treatment?
It is called biological treatment because it heavily relies on native aerobic and anaerobic microbes to consume and break down the organic waste present in the primary effluent.
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