AP BIOLOGY

Detailed explanation-1: -Seismonastic movements-These types of nastic movements occur in response to the mechanical stimuli of touch, contact, water pressure etc. For example, drooping of the leaves of Mimosa pudica when touched. Photonastic movements-These occur in response to light but do not follow the direction of light.

Detailed explanation-2: -(a) Seismonastic movement are the various type of responses and movements which are shown by plants on receiving stimulus. The stimulus may be electrical, chemical, pressure, touch, heat, etc. The plant shows some kind of change in their structure and move away from the source of stimulus.

Detailed explanation-3: -Mechanical stimulation like touch or contact, rapid winds, raindrops, etc. cause seismonastic movement in plants. Many plant parts, including the stigmas, stamens, and leaves, exhibit seismonastic movements. For example-The leaflets of the Mimosa pudica plant rapidly fold and droop in response to touch.

Detailed explanation-4: -Seismonasty or Thigmonasty: Response to shock/contact/vibration. This type of nastic movement is due to mechanical stimuli, e.g. touch, strong wind, raindrops, foreign body, etc.

Detailed explanation-5: -Note: Seismonastic movements are the actions in which the plants pass away from the stimulus. For example, the plant Mimosa pudica shows a foldaway of the fliers when affected by touch. Such movements are not only shown towards the touch. Thus, the Seismonastic movements play a major role in the life of the plants.