AP BIOLOGY

Detailed explanation-1: -Plants respond to various stimuli. Response to environmental stimuli is known as tropism and the stimuli may be light, water, gravity, etc. Various types of tropism are: Phototropism: Movement or growth of plants towards light is called phototropism.

Detailed explanation-2: -Touch responses can turn plants into aggressors against animals, trapping and devouring them, and enable flowers to be active in ensuring crosspollination and shoots to climb to sunlit heights.

Detailed explanation-3: -Some common plant stimuli include light, gravity, water, movement of the sun, and touch. The naming of the tropism is associated with the stimulus. For example, the movement of plant roots towards water is called hydrotropism.

Detailed explanation-4: -The movement of plants due to gravity is called gravitropism. They also do respond to the light. The aerial parts respond positively and grow towards the light whereas the roots respond negatively and grow backward to light. The movement due to lights is known as phototropism.

Detailed explanation-5: -In plants, the general response to gravity is well known: their roots respond positively, growing down, into the soil, and their stems respond negatively, growing upward, to reach the sunlight.