CBSE Class 12 Biology Very Short Answer Questions – Environmental Issues (NCERT Based)

Unit V: Ecology and Environment | Chapter 16: Environmental Issues

CBSE Class 12 Biology Chapter 16 Very Short Answer Questions – Environmental Issues (NCERT)

Course & Examination Details

• Course: CBSE Class 12 Biology
• Unit: Unit V – Ecology and Environment
• Chapter: Chapter 16 – Environmental Issues
• Board: Central Board of Secondary Education (CBSE)
• Syllabus Base: Strictly as per NCERT Textbook
• Exam Use: CBSE Board Exams, School Tests, Quick Revision (1 Mark Questions)

Very Short Answer Type Questions (20–30 Words Each)

(Prepared strictly as per NCERT syllabus and CBSE answer-writing standards)

Section A: Air Pollution and Its Control (Q1–Q8)

Q1. What is air pollution?
Ans: Air pollution is the presence of harmful solid, liquid, or gaseous substances in the atmosphere at concentrations injurious to living organisms.

Q2. Name one major source of carbon monoxide.
Ans: Incomplete combustion of fossil fuels in automobiles.

Q3. What is smog?
Ans: Smog is a mixture of smoke and fog formed due to atmospheric pollutants.

Q4. Name one effect of air pollution on human health.
Ans: Respiratory disorders such as asthma and bronchitis.

Q5. What is acid rain?
Ans: Acid rain is precipitation containing sulphuric and nitric acids formed from SO₂ and NOₓ.

Q6. Which device is used in industries to control air pollution?
Ans: Electrostatic precipitator.

Q7. Why are catalytic converters used in vehicles?
Ans: To reduce harmful exhaust gases like CO and nitrogen oxides.

Q8. Name one eco-friendly fuel used to reduce air pollution.
Ans: Compressed Natural Gas (CNG).

Section B: Water Pollution and Its Control (Q9–Q16)

Q9. What is water pollution?
Ans: Water pollution is contamination of water bodies by harmful substances, making water unfit for use.

Q10. Name one major source of water pollution.
Ans: Domestic sewage.

Q11. What is eutrophication?
Ans: Excessive nutrient enrichment of water bodies leading to algal blooms.

Q12. How does eutrophication affect aquatic life?
Ans: It reduces dissolved oxygen, causing fish death.

Q13. What are water-borne diseases?
Ans: Diseases like cholera and typhoid transmitted through contaminated water.

Q14. Name one method to control water pollution.
Ans: Treatment of sewage before discharge.

Q15. Why should biodegradable detergents be used?
Ans: They reduce water pollution and decompose easily.

Q16. What is bioaccumulation?
Ans: Accumulation of toxic substances in organisms over time.

Section C: Solid Waste Management (Q17–Q24)

Q17. What is solid waste?
Ans: Solid waste includes garbage, refuse, and discarded materials from homes and industries.

Q18. Name one problem caused by improper waste disposal.
Ans: Spread of diseases.

Q19. What is composting?
Ans: Biological decomposition of organic waste into manure.

Q20. What is recycling?
Ans: Reprocessing waste materials into usable products.

Q21. What is incineration?
Ans: Burning of waste at high temperatures to reduce volume.

Q22. What is a sanitary landfill?
Ans: A site where waste is safely buried to prevent pollution.

Q23. Why is waste segregation important?
Ans: It helps in efficient recycling and disposal.

Q24. Name one hazardous solid waste.
Ans: Electronic waste (e-waste).

Section D: Agrochemicals and Their Effects (Q25–Q31)

Q25. What are agrochemicals?
Ans: Chemicals like fertilizers, pesticides, and herbicides used in agriculture.

Q26. Name one harmful effect of excessive fertilizer use.
Ans: Water pollution and eutrophication.

Q27. What is biomagnification?
Ans: Increase in concentration of toxic substances at higher trophic levels.

Q28. Why are pesticides harmful to non-target organisms?
Ans: They kill beneficial organisms along with pests.

Q29. Name one eco-friendly alternative to agrochemicals.
Ans: Organic farming.

Q30. What is integrated pest management?
Ans: Use of biological and mechanical methods to control pests.

Q31. How do agrochemicals affect soil fertility?
Ans: They degrade soil structure and microbial activity.

Section E: Radioactive Wastes (Q32–Q35)

Q32. What are radioactive wastes?
Ans: Wastes containing radioactive substances from nuclear plants and laboratories.

Q33. Name one harmful effect of radioactive waste.
Ans: Cancer and genetic mutations.

Q34. Why are radioactive wastes dangerous?
Ans: They remain hazardous for long periods.

Q35. How are radioactive wastes disposed of?
Ans: By deep burial in secure geological sites.

Section F: Greenhouse Effect and Global Warming (Q36–Q41)

Q36. What is greenhouse effect?
Ans: Trapping of heat in Earth’s atmosphere by greenhouse gases.

Q37. Name one greenhouse gas.
Ans: Carbon dioxide.

Q38. What is global warming?
Ans: Gradual increase in Earth’s average temperature.

Q39. Name one effect of global warming.
Ans: Melting of glaciers.

Q40. How can global warming be controlled?
Ans: By reducing greenhouse gas emissions.

Q41. Which activity increases greenhouse gases?
Ans: Burning of fossil fuels.

Section G: Ozone Depletion and Deforestation (Q42–Q50)

Q42. What is the ozone layer?
Ans: A stratospheric layer protecting Earth from UV radiation.

Q43. Name one cause of ozone depletion.
Ans: Chlorofluorocarbons (CFCs).

Q44. What is ozone hole?
Ans: Thinning of ozone layer over polar regions.

Q45. Name one effect of ozone depletion.
Ans: Increased skin cancer risk.

Q46. What is deforestation?
Ans: Large-scale removal of forest cover.

Q47. Name one cause of deforestation.
Ans: Expansion of agriculture.

Q48. How does deforestation affect climate?
Ans: It increases carbon dioxide levels and global warming.

Q49. Name one method to control deforestation.
Ans: Afforestation.

Q50. Why are forests important for the environment?
Ans: They regulate climate, conserve biodiversity, and prevent soil erosion.

CBSE Exam Note

These Very Short Answer Questions (1 mark) are ideal for quick revision, definitions, and fact-based questions in CBSE Class 12 board examinations, strictly aligned with NCERT Chapter 16 – Environmental Issues.