Question

The closing and opening of the leaves of Mimosa pudica is due to

• A. seismonastic movement
• B. chemonastic movement
• C. thermonastic movement
• D. hydrotropic movement.

Answer 1

The Correct Option is A

The question is about the mechanism responsible for the movement of the leaves in Mimosa pudica, a plant known for its rapid response to touch. Let's analyze the given options one by one:

1. Seismonastic movement: This is a type of nastic movement in plants triggered by mechanical stimuli like touch or shaking. In Mimosa pudica, when the leaves are touched or shaken, they fold or droop. This rapid movement is due to changes in the turgor pressure within the cells at the base of the leaflets. The rapid loss and regain of turgor pressure cause the leaves to close and open, respectively. Therefore, this is the correct answer for the observed movement in Mimosa pudica.
2. Chemonastic movement: This movement is induced by chemical stimuli. While some plants do exhibit movement in response to chemical changes, this is not applicable to the movement seen in Mimosa pudica leaves, as it is not a chemical stimulus but a mechanical one that prompts the immediate movement.
3. Thermonastic movement: These movements occur in response to changes in temperature. For example, some flowers open and close with changes in temperature. However, this is not related to the movement seen in Mimosa pudica, where the leaves respond to mechanical touch and not temperature.
4. Hydrotropic movement: Hydrotropism is the growth movement in response to water gradients. It is generally associated with root growth towards moisture rather than the movement of leaves in response to touch, which again is not applicable in the case of Mimosa pudica.

Based on the explanation above, the correct answer to the question regarding the movement in Mimosa pudica is seismonastic movement.