CBSE Class 10 Answered

Plant shows two types of movements- one dependent on growth and the other independent of growth.

Types of tropism:

1. The movement of a plant part in response to light is called phototropism. The stem of a growing plant bends towards the light (positive phototropism), while roots of a plant move away from light (negative phototropism).
2. The movement of a plant part in response to gravity is called geotropism. The roots of a plant move downwards in the direction of gravity. On the other hand the stem of a plant grow upwards and away from the earth.
3. The movement of a plant part in response to chemicals is called chemotropism.

Nastic Movements:
In nastic movements the movement of plant part is neither towards the stimulus nor away from the stimulus. This movement is not a directional movement of the plant part with respect to the stimulus. In nastic movements growth may or may not take place.