UPSC Prelims 2018 · GS Paper I
Question 99: Science and Technology
Consider the following :
- 1.Birds
- 2.Dust blowing
- 3.Rain
- 4.Wind blowing
Which of the above spread plant diseases ?
AnswerUPSC’s answer is (d).
Plant pathogens spread by many agents. Birds carry spores, seeds and insects between plants; wind and blowing dust carry fungal spores and bacteria over long distances; and rain splash moves spores from leaf to leaf and onto the soil. So all four spread plant diseases. Remember: other carriers include insects, water, soil, seeds and humans.
- 1. Birds carry spores and insects between plants.
- 2. Blowing dust carries spores and bacteria.
- 3. Rain splash moves spores between plants.
- 4. Wind carries spores over long distances.
How you could have got this
- If you were sure statement 2 is correct, (a) and (b) go: each of them leaves 2 out.
What you needed to know: Blowing dust carries spores and bacteria.
- Then, if you were sure statement 3 is correct, (c) goes: it leaves 3 out.
What you needed to know: Rain splash moves spores between plants.
Only (d) is left. You didn’t need statements 1 or 4.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Incomplete: dust and wind also spread disease.
- (b) Incomplete: birds and dust also spread disease.
- (c) Incomplete: rain also spreads disease.
- (d) Right: all four.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2018, General Studies Paper I, Series A. The paper on upsc.gov.in.