Question

Charles and Francis Darwin concluded from their experiments on phototropism by grass seedlings that the part of the seedling that detects the direction of light is the A) base of the coleoptile. B) part of the coleoptile that bends during the response. C) cotyledon. D) tip of the coleoptile.

Answer 1

Answer:

The correct answer is D.

Explanation:

We can rule out cotyledon because it is the embryonic leaf of the seed and it doesn't take part in phototropism.

Which part of the coleoptile is responsible for phototropism can be derived from empiric data by preventing some parts of the coleoptile to recieve light. In this case preventing the tip of coleoptile prevents photostrism movement so correct answer is D (see figures).