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: Auxin Synthesis at Shoot Tip
The shoot tip synthesizes the plant growth hormone auxin. Auxins, produced in the apical meristem, drive cell elongation and overall plant growth.

Step 2: Phototropism - Shoot Bending Towards Light
Phototropism describes the shoot's bending response towards a light source, such as a window. This occurs because:

- Auxin, synthesized at the shoot tip, migrates from the illuminated side to the shaded side of the plant when light is directional.
- Increased auxin on the shaded side stimulates greater cell elongation there than on the light-exposed side.
- This differential elongation causes the shoot to bend towards the light source.

Step 3: Summary
Auxin, the growth hormone from the shoot tip, mediates phototropism, leading the plant shoot to bend towards directional light, like that from a window.