Class 12 Biology - KERALA
Microbes in Human Welfare
Microbes in Human Welfare is a scoring and conceptually straightforward chapter in the Kerala SCERT Class 12 Biology syllabus. It explores the diverse roles microorganisms play in enhancing human life, moving beyond the perception of them merely as disease-causing agents. Students will learn about microbes in household food production, industrial processes, sewage treatment plants, as biofertilizers, and as biological control agents. Mastery of specific scientific names (like Lactobacillus, Saccharomyces cerevisiae, Trichoderma, and Bacillus thuringiensis) and their precise applications is crucial for scoring high marks in the board examinations.
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
Microbes are grown in large vessels called fermentors to produce valuable commercial products like beverages (wine and beer using yeast) and life-saving antibiotics (such as penicillin from Penicillium notatum).
Microbes in Sewage Treatment
Primary treatment involves physical removal of particles, while secondary (biological) treatment uses aerobic and anaerobic microbes to reduce the Biological Oxygen Demand (BOD) of wastewater before release.
Microbes as Biocontrol Agents
The use of biological methods to control plant diseases and pests. For example, Bacillus thuringiensis bacteria are used to control butterfly caterpillars, and Trichoderma fungi protect roots from pathogens.
Microbes as Biofertilizers
Organisms that enrich the nutrient quality of the soil. Examples include nitrogen-fixing bacteria like Rhizobium in root nodules, free-living Azospirillum, and mycorrhizal fungi that absorb phosphorus.
Important Formulas
Board Exam Info
In the Kerala SCERT Class 12 Biology board examinations, this chapter typically carries around 4 to 6 marks. Questions usually include direct short answers asking for the scientific names of microbes and their specific products (enzymes, antibiotics, bioactive molecules), matching columns, and explanatory questions on sewage treatment or biogas production.
Frequently Asked Questions
What are statins and where are they obtained from?
Statins are blood-cholesterol lowering agents produced by the yeast Monascus purpureus. They act by competitively inhibiting the enzyme responsible for synthesis of cholesterol.
What is BOD and why is it important in sewage treatment?
BOD stands for Biological Oxygen Demand. It refers to the amount of oxygen that would be consumed if all the organic matter in one liter of water were oxidized by bacteria. Higher BOD indicates higher pollution potential.
Name the bacterium used in the production of acetic acid, butyric acid, and lactic acid.
Acetic acid is produced by Acetobacter aceti, butyric acid by Clostridium butylicum, and lactic acid by Lactobacillus.
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