Science
Plants have neither a nervous system nor muscles, even then they respond to stimuli. For example, the leaves of chhui-mui (touch-me-not) plant when touched begin to fold up and droop.
(a) How is the information communicated in "touch-me-not" plants ?
(b) What enables the plant cells to bring out the observable response ?
(c) Differentiate the movement mentioned above from the movement of tendrils in a pea plant.
Answer
(a) In the touch-me-not (chhui-mui) plant, the information about touch is communicated through electrical and chemical signals from the affected part to the nearby cells. These signals cause changes in the water pressure inside cells of certain specialized cells at the base of the leaflets and petioles.
(b) The change in water pressure enables the plant cells to bring about the observable response. When touched, water moves out of the cells, making them flaccid, which causes the leaves to fold up and droop.
(c) The movement in the touch-me-not plant is a nastic movement, which occurs independently of the direction of the stimulus (the leaves fold whether touched from any side). In contrast, the movement of tendrils in pea plants is a tropic movement, which occurs in the direction of the stimulus (tendrils bend towards or coil around the object they touch).
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