Phototropism and gravitropism in plants are controlled by.
a. genes
b. hormones
c. enzymes
d. tree sap

Option B.

Explanation:Phototropism is the process in which plant grow in response to light. Where "Photo'' means light and ''Tropisms'' are responses to external stimuli in this case stimuli against light.

Now, going back to the question

Plant cells grows faster in the presence of the hormone auxin. As a result when a plant senses a light from a direction, auxin molecules accumulates to the side that is further away from the light, due to which the plant cells that are further away from the light experience a greater auxin concentration and grow faster, due to which shoot gets bend towards the direction of the applied light. Gravitropism is a process of growth by a plant in response to gravity pulling on it. Roots show positive gravitropism i.e they will grow with the gravitational pull and stems show negative gravitropism that is they will grow against gravitational pull.Auxin is a plant hormone which promotes stem elongation and inhibits the growth of lateral buds.Auxin helps in maintaining apical dominance, which means in presence of auxin the plant will grow Vertically upward i.e against the gravity. Hence Auxin promotes gravitropism.

Result: Phototropism and Gravitropism is controlled by Hormones

When plants die fungi breaks them down

Other organisms can change their behavior to take the place of the plants in the ecosystem.