Question

Name the plant growth hormone which is synthesized at the shoot tip. Explain why the shoot of a potted plant bends towards light coming from a window.

Answer 1

Step 1: Plant growth hormone synthesized at the shoot tip
The plant growth hormone synthesized at the shoot tip is called auxin. Auxins are produced in the apical meristem (the shoot tip) and are responsible for promoting cell elongation and growth in plants.

Step 2: Why the shoot bends towards light (Phototropism)
The bending of the shoot towards light coming from a window is known as phototropism, a growth response of plants to light.

- When light comes from one direction (in this case, from the window), the auxin produced at the shoot tip moves away from the light side to the shaded side of the plant.
- Auxin promotes more cell elongation on the shaded side, making the cells grow longer on that side compared to the side exposed to light.
- As a result, the shoot bends towards the light source because the cells on the shaded side are elongating more than those on the light-exposed side.

Step 3: Conclusion
Auxin is the hormone responsible for plant growth at the shoot tip, and phototropism is the response that causes the shoot of a plant to bend towards the light coming from a window.