Define each of the following terms and explain how each of them can benefit the plant.
a. gravitropism
b. phototropism
c. thigmotropism
d. photoperiod

definition with benefit is given below of

1st. gravitropism

2nd. phototropism

3rd. thigmotropism

4th. photoperiod

Explanation:

1st is gravitropism

gravitropism is process in which plant grow in the direction that gravity act

It is also called geotropism

and

Gravitropism is important for plants because it directs the roots to grow in the downward direction that is important for obtaining nutrients

2nd is phototropism

phototropism  is the process in which plant growth directed by the light

and

we know plants need light to carry out photosynthesis

so  Phototropism direct the growth of the stem and branch toward sunlight

3rd is thigmotropism

thigmotropism is the directional change in growth of plant in response to a touch stimulus

and

thigmotropism is especially important for climbing plant that is use support to climb up

4th is photoperiod

photoperiod is the physiological change in organism in the response to length of the day and night

and

it play important role to determining the physiological developmental process in the plant such as budding and tuberization

the electromagnetic energy from the sun arrives in the form of visible and invisible light.

stimulus is a change in the environment that causes an organism to react. the response is the reaction to the stimulus. some examples of stimuli for zebras are drought, to many predators, and bad feeding grounds such as dead grass or plants. zebras respond to stimuli just like all other living organisms