AP BIOLOGY

Detailed explanation-1: -Tropisms and nastic movements are both plant responses to external stimuli. however tropisms are depend on the direction of the stimulus nastic movements do not depend on the direction of a stimulus.

Detailed explanation-2: -Nastic movements are different from tropic movements (tropisms). Tropisms are directional movements or growth response of a plant to the stimulus. In nastic movements, the response of the plant is non-directional. An example of tropism is thigmotropism, which is a growth response to the touch stimulus.

Detailed explanation-3: -Because nastic responses are non-directional they cannot be described as positive or negative. Nastic responses are usually faster, reversible movements rather than growth responses. Mimosa pudica also known as the ‘the sensitive plant’ displays a very rapid response to touch.

Detailed explanation-4: -This movement takes place in the flat organs of the plant like leaves, petals of flowers etc. Examples of nastic movements are: 1. In the Mimosa pudica plant, when we touch the leaves of the plant they fold up.