Question
Briefly describe the different types of tropic movements in plants.
Answer
Plants exhibit different types of tropic movements, which are directional growth responses in response to external stimuli.
The three main types of tropic movements in plants are:
- Phototropism: This is the directional growth response of plants towards or away from a light source. Shoots exhibit positive phototropism, growing towards the light, while roots exhibit negative phototropism, growing away from the light. The movement is caused by the hormone auxin, which accumulates on the shaded side of the plant, causing the cells to elongate and grow towards the light.
- Geotropism: This is the directional growth response of plants in response to gravity. Roots exhibit positive Geotropism, growing towards the direction of gravity, while shoots exhibit negative Geotropism, growing in the opposite direction. The movement is caused by the hormone auxin, which accumulates at the bottom of the root, causing it to elongate and grow downwards.
- Thigmotropism: This is the directional growth response of plants in response to touch or mechanical stimuli. The movement can either be towards the stimulus or away from it, depending on the plant species. The movement is caused by the differential growth of cells on either side of the plant, causing it to bend or grow in response to the touch.
