UPSC CSE Prelims
Environmental Issues & Challenges Previous Year Questions (PYQs)
Showing solved Previous Year Questions for Chapter: Environmental Issues & Challenges
Topic Breakdown: Scroll →
Mycorrhizal Biotechnology has been used in rehabilitating degraded sites because mycorrhiza enables the plants to -
- Resist drought and increase absorptive area
- Tolerate extremes of pH
- Resist disease infestation
Select the correct answer using the codes given below:
Detailed Explanation:
✅ Statement 1 – Correct: Mycorrhizal fungi form symbiotic associations with plant roots, greatly increasing the effective absorptive surface area (fungal hyphae extend beyond roots) and improving water uptake, enabling plants to resist drought stress.
✅ Statement 2 – Correct: Mycorrhizae help plants tolerate extreme pH conditions (both acidic and alkaline soils) by facilitating nutrient acquisition even when pH levels reduce nutrient availability.
✅ Statement 3 – Correct: Mycorrhizae provide bioprotection against disease infestation by competing with soil-borne pathogens, producing antimicrobial compounds, and enhancing plant immune responses.
Consider the following statements: Chlorofluorocarbons, known as ozone-depleting substances, are used
- in the production of plastic foams
- in the production of tubeless tyres
- in cleaning certain electronic components
- as pressurizing agents in aerosol cans
Which of the statements given above is/are correct?
Detailed Explanation:
✅ Statement 1 – Correct: CFCs were widely used as blowing agents in the production of plastic foams (polystyrene, polyurethane) for insulation and packaging.
❌ Statement 2 – Incorrect: Tubeless tyres are manufactured through vulcanization using sulfur; CFCs have no role in tyre production.
✅ Statement 3 – Correct: CFC-113 was extensively used as a solvent for cleaning electronic components and circuit boards due to its non-flammable, residue-free properties.
✅ Statement 4 – Correct: CFCs served as propellants/pressurizing agents in aerosol cans (hairsprays, deodorants) before being phased out under the Montreal Protocol.
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