Given below are figures representing four different situations/examples of genetic and environmental (temperature) effects on plant height in two varieties of a plant species. In Figures A, C, and D, solid and dashed lines represent the mean values of plant height for the two varieties G1 and G2, respectively. In Figure B, the solid and dashed lines overlap.

Given below are four statements explaining the four figures:

i. Plant height is influenced primarily by the genotype of the two varieties.
ii. Variation in plant height is influenced only by temperature, and genotype has no effect.
iii. Genotype and temperature collectively have an additive effect on plant height.
iv. Both genotype and environment have an effect on plant height, with the two varieties responding differently to the environment.

Correct option is A

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Each graph represents a different scenario of how plant height is influenced by genotype (G1, G2) and environmental factors (temperature). Let's analyze them one by one:

1. Figure A:

   • The plant height remains constant across temperature changes for both G1 and G2.
   • This suggests that genotype alone determines plant height, and the environment (temperature) has no effect.
   • This matches Statement i: "Plant height is influenced primarily by the genotype of the two varieties."
   • Thus, A → i

2. Figure B:

   • The plant height increases with temperature, and both genotypes (G1, G2) respond in the same way (overlapping solid and dashed lines).
   • This means only temperature influences plant height, and genotype has no effect.
   • This matches Statement ii: "Variation in plant height is influenced only by temperature, and genotype has no effect."
   • Thus, B → ii

3. Figure C:

   • Both G1 and G2 show an increase in plant height as temperature increases, but the two lines remain separate.
   • This means both genotype and temperature contribute to plant height in an additive manner (i.e., no interaction but both factors matter).
   • This matches Statement iii: "Genotype and temperature collectively have an additive effect on plant height."
   • Thus, C → iii

4. Figure D:

   • G1 and G2 respond differently to changes in temperature—one increases while the other decreases.
   • This indicates a genotype-environment interaction, where both factors affect plant height, but the response to temperature differs between genotypes.
   • This matches Statement iv: "Both genotype and environment have an effect on plant height, with the two varieties responding differently to the environment."
   • Thus, D → iv

Final Answer :    A - i, B - ii, C - iii, D - iv → Option 1 is the correct answer.