Part-I MCQs: the 20 compulsory multiple-choice questions of the CSS 2026 General Science & Ability paper, with answers and short explanations.

Answers

1. Rapid short-term weather changes are most strongly influenced by: (B) Atmospheric pressure systems.

2. The primary structure of a protein is determined by its: (A) Amino acid sequence.

3. In plants, lignin primarily provides: (B) Mechanical support, by strengthening cell walls.

4. The Montreal Protocol focuses on the reduction of: (C) Ozone-depleting substances.

5. A key indicator of drinking water microbiological safety is: (D) E. coli, which signals faecal contamination.

6. Bioavailability of nutrients in food refers to: (A) Nutrients absorbed by the body.

7. A CPU's instruction cycle primarily depends on the following for coordinating all operations: (C) Control Unit.

8. The protocol mapping domain names to IP addresses is: (C) DNS, the Domain Name System.

9. Knowledge graphs enhance AI reasoning by representing data as: (C) Node-edge relationships.

10. Wind turbines convert which form of energy into electricity? (D) Kinetic, the energy of moving air.

11. LEDs save energy because light is produced by: (B) Electron-hole recombination.

12. The major storage lipid in animals is: (B) Triglyceride.

13. The most responsible pollutant for photochemical smog is: (C) Nitrogen oxides. Ozone is a product formed from them in sunlight.

14. Acid rain primarily results from emissions of: (B) SO₂ and NOₓ.

15. A major global impact of particulate matter (PM2.5) is: (A) Respiratory illness.

16. Heavy metal contamination is most harmful because it: (B) Biomagnifies in food chains.

17. Fibre optic cables support high bandwidth because data travels as: (C) Light signals with minimal attenuation.

18. Remote sensing is primarily used in environmental studies to: (A) Collect large-scale Earth surface data.

19. A Decision Support System differs from routine MIS by providing: (A) Predictive and unstructured problem-solving.

20. Satellite signals suffer significant latency mainly due to: (D) Long propagation distance to orbit.