What are ‘nastic’ and ‘curvature’ movements? Give one example of each.

Nastic movements- These are nondirectional movements which takes place in living parts of plant due to the stimulus like temperature, amount of water etc.

For example- Whenever there is excess amount of water stomata gets opened. This is a nondirectional movement which takes place due to presence of excess water.

Curvature movements- These are directional movements which take place due to stimulus like light, some chemicals etc.

For example- Shoot of a plant moves toward the direction of light. Here the movement is directional due to presence of light in a particular direction.