Which Pigment is Responsible for the Phototropism Responses of Plants

Question

Which pigment is responsible for the phototropism responses of plants?
A) Phytochrome
B) Ethylene
C) Chlorophyll
D) Auxin
E) Xanthophyll

Accepted Answer

Phytochrome is a pigment that is responsible for the phototropism responses of plants. Phototropism is the growth of a plant towards or away from light. Phytochrome is a protein that exists in two forms, Pr and Pfr. Pr is the inactive form of phytochrome, while Pfr is the active form. When light strikes phytochrome, it causes Pr to convert to Pfr. Pfr then triggers a series of events that lead to the growth of the plant towards or away from the light.