Chapter 10: Microbes in Human Welfare – Very Short Answer Type Questions

CBSE Class 12 Biology Very Short Answer Questions (NCERT): Microbes in Human Welfare

Course & Examination Details

Course: CBSE Class 12 Biology
Unit: Unit III – Biology and Human Welfare
Chapter: Chapter 10 – Microbes in Human Welfare
Prescribed Textbook: NCERT Biology Class XII
Examination: CBSE Class 12 Board Examination
Question Type: Very Short Answer Type (VSA)
Answer Length: 20–30 words
Syllabus Alignment: Strictly as per NCERT

Section A: Microbes in Household Products

Q1. What role does Lactobacillus play in curd formation?

Answer: Lactobacillus converts lactose into lactic acid, coagulating milk proteins and improving digestibility and nutritional quality.

Q2. Name the microorganism used in bread making.

Answer: Yeast (Saccharomyces cerevisiae) is used to ferment sugars and release carbon dioxide.

Q3. Why does idli batter rise during fermentation?

Answer: Fermentation by lactic acid bacteria and yeast produces carbon dioxide, causing batter to rise.

Q4. State one health benefit of fermented foods.

Answer: Fermented foods improve digestion and increase vitamin content, especially vitamin B12.

Q5. What is fermentation?

Answer: Fermentation is microbial conversion of sugars into acids, alcohol, or gases.

Section B: Microbes in Industrial Products

Q6. Name the microorganism producing penicillin.

Answer: Penicillium produces the antibiotic penicillin.

Q7. What are antibiotics?

Answer: Antibiotics are substances produced by microbes that inhibit growth of disease-causing microorganisms.

Q8. Which microbe produces citric acid?

Answer: Aspergillus niger produces citric acid.

Q9. Name one use of microbial enzymes.

Answer: Proteases are used in detergents to remove protein stains.

Q10. Which microbe produces statins?

Answer: Monascus purpureus produces statins.

Q11. What is the function of statins?

Answer: Statins reduce blood cholesterol levels.

Q12. Name the bioactive molecule used as an immunosuppressant.

Answer: Cyclosporin A is used as an immunosuppressant.

Q13. Which microorganism produces cyclosporin A?

Answer: Trichoderma polysporum produces cyclosporin A.

Q14. What is the role of yeast in alcoholic beverage production?

Answer: Yeast ferments sugars into ethanol and carbon dioxide.

Q15. What are bioreactors used for?

Answer: Bioreactors are used for large-scale production of microbial products.

Section C: Microbes in Sewage Treatment

Q16. What is sewage?

Answer: Sewage is wastewater containing organic matter and pathogenic microorganisms.

Q17. What is the primary treatment of sewage?

Answer: Primary treatment involves physical removal of large and small particles.

Q18. Define BOD.

Answer: BOD is the biochemical oxygen demand, indicating organic matter in water.

Q19. What happens during secondary sewage treatment?

Answer: Aerobic microbes degrade organic matter, reducing BOD.

Q20. What are flocs?

Answer: Flocs are masses of bacteria and fungi formed during sewage treatment.

Q21. Why is aeration important in secondary treatment?

Answer: Aeration supplies oxygen for aerobic microbial activity.

Q22. What is activated sludge?

Answer: Activated sludge is microbial biomass settled after secondary treatment.

Q23. Name the gas produced during anaerobic sludge digestion.

Answer: Methane is produced during anaerobic digestion.

Q24. How does sewage treatment protect the environment?

Answer: It prevents water pollution and protects aquatic life.

Section D: Microbes in Biogas Production

Q25. What is biogas?

Answer: Biogas is a fuel gas produced by anaerobic digestion of organic waste.

Q26. Name one methanogenic bacterium.

Answer: Methanobacterium is a methanogenic bacterium.

Q27. Which gas is the major component of biogas?

Answer: Methane is the major component of biogas.

Q28. Why is biogas considered eco-friendly?

Answer: Biogas is renewable and reduces pollution.

Q29. What is the slurry left after biogas production used for?

Answer: It is used as nutrient-rich manure.

Section E: Microbes as Biocontrol Agents

Q30. What is biocontrol?

Answer: Biocontrol is the use of biological agents to control pests and pathogens.

Q31. Name the bacterium used as a biopesticide.

Answer: Bacillus thuringiensis is used as a biopesticide.

Q32. How does Bacillus thuringiensis control insects?

Answer: It produces toxins that kill insect larvae.

Q33. Name a fungal biocontrol agent.

Answer: Trichoderma species are used as biocontrol agents.

Q34. Give one advantage of biocontrol.

Answer: Biocontrol reduces chemical pesticide use.

Q35. Name a predator used in biological control.

Answer: Ladybird beetle controls aphids.

Section F: Microbes as Biofertilisers

Q36. What are biofertilisers?

Answer: Biofertilisers are microorganisms that enhance soil nutrient availability.

Q37. Name a symbiotic nitrogen-fixing bacterium.

Answer: Rhizobium is a symbiotic nitrogen-fixing bacterium.

Q38. Which plants form symbiosis with Rhizobium?

Answer: Leguminous plants form symbiosis with Rhizobium.

Q39. Name one free-living nitrogen-fixing bacterium.

Answer: Azotobacter is a free-living nitrogen fixer.

Q40. Name one cyanobacterium used as biofertiliser.

Answer: Anabaena is used as a biofertiliser.

Q41. What is mycorrhiza?

Answer: Mycorrhiza is a symbiotic association between fungi and plant roots.

Q42. Name a mycorrhizal fungus.

Answer: Glomus is a mycorrhizal fungus.

Q43. How does mycorrhiza benefit plants?

Answer: It increases phosphorus uptake and provides disease resistance.

Q44. Why are biofertilisers eco-friendly?

Answer: They improve soil fertility without chemical pollution.

Section G: Integrated & Exam-Oriented

Q45. How do microbes improve food quality?

Answer: Microbes enhance taste, texture, and nutritional value through fermentation.

Q46. Which microbes are called probiotics?

Answer: Beneficial microbes like Lactobacillus that improve gut health are probiotics.

Q47. Why is microbial sewage treatment important?

Answer: It reduces organic pollutants and prevents environmental contamination.

Q48. How do microbes contribute to sustainable agriculture?

Answer: They act as biofertilisers and biocontrol agents.

Q49. Why is Chapter 10 important for CBSE exams?

Answer: It covers applied microbiology frequently asked in board exams.

Q50. Name one industrial product obtained using microbes.

Answer: Antibiotics like penicillin are industrial microbial products.