Question

Differentiate between tropic and nastic movements in plants.

Answer 1

Tropic movements

Nastic movements

1. It can be easily observed in stems and roots. 2. It is due to unilateral stimulus which causes unequal growth on the two sides of a stem, root and tendril 3. Movement is related to stimulus, i.a., plant organs either move towards the source of stimulus or away from it. Stimuli which causes movements in plants are gravity, light, touch, water and chemical substances. 4. Example: Bending of root towards gravity and shoot toward light.

1. It is clearly observed in bilaterally symmetrical organs such as leaves and petals of flowers. 2. The movements occur due to stimulus of light and temperature 3. Opening and closing of flowers of evening primrose and tobacco at the night and day respectively. This is due to unequal growth. 4. Example: Leaves of 'touch-me-not' plant bend and droop on touching