Question
What is tropic movements? Describe any two types of tropic movements in plants.
Answer
Tropic movements are directional plant movements in response to external stimuli such as light, gravity, touch, or chemicals.
Two types of tropic movements in plants are:
- Phototropism: Phototropism is a plant’s growth response to light. If the light source is coming from one direction, the plant will grow towards it (positive phototropism) or away from it (negative phototropism). The photoreceptor molecule responsible for detecting light is called phytochrome, which is found in the plant’s leaves and stem tips.
An example of phototropism is a sunflower, which follows the sun’s movement throughout the day to maximize exposure to sunlight. - Geotropism: Geotropism is a plant’s growth response to gravity. The roots grow downwards, towards the direction of the gravitational pull (positive Geotropism), while the stem grows upwards, away from the direction of the gravitational pull (negative Geotropism).
An example of Geotropism is a potted plant that has been placed on its side – the stem will bend upwards towards the sky, while the roots will bend downwards towards the soil.
