Phototropic curvature is the result of uneven distribution of
- gibberellin
- phytochrome
- cytokinins
- auxin
Answer
(4) auxin
Solution
As per NCERT, Charles and Francis Darwin observed that the coleoptiles of canary grass bend towards light (phototropism) due to a stimulus from the tip; F.W. Went later isolated auxin from the tips of oat coleoptiles.
∵ Unilateral light causes more auxin on the shaded side, which elongates more,
∴ phototropic curvature is the result of uneven distribution of auxin.
Answer: (4)