AP BIOLOGY

Detailed explanation-1: -Plants can either display a negative or positive movement in response to a stimulus. It is positive tropism when the movement is towards the direction of stimuli while it is negative tropism when the movement is away from the stimuli.

Detailed explanation-2: -Tropisms can have a sign: positive if the plant grows toward or in the direction of the stimulus or negative if it moves away from the stimulus.

Detailed explanation-3: -The movement or growth of any part of a plant in response to an external stimulus is called tropism or tropic movement.

Detailed explanation-4: -A tropism is plant movement in response to an external stimulus in the environment. If a plant moves towards a stimulus, then it exhibits positive tropism; if a plant moves away from a stimulus, then it exhibits negative tropism.

Detailed explanation-5: -In a positive tropism, the plant moves towards the stimulus. One familiar example is positive phototropism, in which a plant moves towards sunlight. Time lapse photography allows us to appreciate the tropisms of plants.