AP BIOLOGY

Detailed explanation-1: -●The movement of the plant part in response to an external stimulus in which the direction of movement is not determined by the direction of stimulus is defined as the nastic movement. ● The folding up of leaves belonging to a sensitive plant such as Mimosa pudica is an example of nastic movement.

Detailed explanation-2: -Mimosa pudica is a seismonastic plant in which the leaves close and the petiole hangs down in response to wind, vibration and touch as a defense mechanism for protection from animals and some insects (Bose 1902, 1907, 1913, 1918, 1926, 1928).

Detailed explanation-3: -The leaves of Mimosa have the capability to display thigmonasty (touch-induced movement). In the sensitive plant, the leaves respond to being touched, shaken, heated or rapidly cooled. The speed of the response depends on the magnitude of the stimulus.

Detailed explanation-4: -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.