After some time, the tip of a plant that has been forced into a horizontal position grows upward. This phenomenon is related to ________.
A) calcium release from the endoplasmic reticulum of shaded cells
B) accumulation of amyloplasts on the lower side of the stem
C) gibberellin production by stems
D) exposure of phytochrome in the stem to red light
E) auxin movement toward the lower side of the stem

Question

Quizplus · Accepted Answer

The phenomenon described in the question is known as gravitropism, which is the directional growth of a plant in response to gravity. This is controlled by the hormone auxin, which moves towards the lower side of the stem when it is placed horizontally. This accumulation of auxin causes the cells on the lower side to elongate, resulting in upward growth of the tip of the plant.

After Some Time, the Tip of a Plant That Has