Question

Distinguish between tropic movements and nastic movements in plants. Give examples to illustrate your answer.

 How do tropisms differ from nasties (or nastic movements)?

Answer 1

	Tropic movements	Nastic movements
1.	Tropic movements are directional growth movements of plant parts in response to an external stimulus.	Nastic movements are non-directional movements of plant parts in response to an external stimulus.
2.	The direction of movement depends on the direction of the stimulus.	The direction of movement does not depend on the direction of the stimulus.
3.	These movements are caused by differential growth of plant parts.	These movements are not caused by growth but mainly by changes in turgor pressure.
4.	These movements are usually permanent.	These movements are usually temporary and reversible.
5.	Example: The stem bends towards light (phototropism).	Example: The leaves of the sensitive plant (Mimosa pudica) fold on touching.