(a) What is meant by nastic movements in plants ? Give one example of nastic movements in plants.(b) What is the difference between photonasty and thigmonasty ?

(a) The non-directional movement of a plant part in response to an external stimulus is known as nastic movement.

Example: The folding and drooping up of leaves in sensitive plants in response to touch.

(b) The difference between Photonasty and Thigmonasty are as follows-

Photonasty	Thigmonasty
1. It is the non-directional movement of a plant part (usually petals of flowers) in response to light.	1. It is the non-directional movement of a plant part in response to the touch of an object.
2. Example- In dandelion flowers, the petals opens and closes in response to the intensity of light.	2. Example- In a Mimosa pudica plant (touch me not plant), the leaves fold up in response to touch.

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Updated on: 24-Mar-2023

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