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UPSC Prelims 1991 · Environment · Nature’s Machinery
Match List I with List II. List I: A. Deforestation · B. Cellular structure · C. Cross pollination · D. Nitrogen fixation. List II: 1. Vacuoles · 2. Maize · 3. Soil erosion · 4. Legumes
- (a) A-3, B-1, C-2, D-4
- (b) A-1, B-2, C-4, D-3
- (c) A-4, B-1, C-2, D-3
- (d) A-2, B-3, C-4, D-1
Show the answer and explanation
Answer: (a) A-3, B-1, C-2, D-4
Deforestation → soil erosion · cell structure → vacuoles · cross pollination → maize (wind-pollinated) · nitrogen fixation → legumes.
The idea
In a matching question, look for the one pair that everyone knows and see how many options carry it. Here “nitrogen fixation – legumes” appears in only one option, so the question is over.
Deforestation → no roots to hold soil → soil erosion → Vacuole → a storage sac inside the cell → Maize → pollen carried by wind to another plant → cross pollination → Legumes → root nodule bacteria → nitrogen fixation
The trap
D–4 (legumes) is known to everyone and appears only in option (a). One sure pair can settle a matching question.
Also know
Maize carries male flowers (the tassel) at the top and female flowers (the silk) lower down on the same plant, which favours cross pollination. Plant cells have one large vacuole; animal cells have small ones or none.
🔒 Maize = wind cross-pollinated (male tassel on top, female silk below).