Question

Explain two types of tropism with suitable examples.

Answer 1

The directional growth movements of the plant due to external stimuli are called tropic movements. It can be either towards the stimulus (positive) or away from it (negative).

There are various types of tropism:

Phototropism - Movement towards the light. For example, shoots of most of the plants, respond by bending towards the light.

Hydrotropism - Movement towards the water. For example, growth movements of roots, in search for water in the soil.

Chemotropism - Movement towards a chemical stimulus. For example, movement of pollen tubes towards ovules.

Geotropism - Movement in response to gravity. For example, shoots of most of the plants, grow upwards and roots of most of the plants, grow downwards.