Question

Name a plant growth hormone synthesized at the shoot tip. Explain its effect on the growth of a plant in response to light.

Answer 1

Step 1: Name of the plant growth hormone:
The plant growth hormone synthesized at the shoot tip is called auxin.

Step 2: Site of synthesis:
Auxins are mainly produced in the shoot tip (apical meristem) of plants.

Step 3: Effect of auxin in response to light (Phototropism):
- Auxin helps in cell elongation and promotes the growth of plant shoots.
- When light falls on one side of the plant, auxin accumulates more on the shaded side of the shoot.
- This causes the cells on the shaded side to elongate more than those on the lighted side.
- As a result, the shoot bends toward the light source.

Step 4: Conclusion:
The hormone auxin, synthesized at the shoot tip, controls the bending of the plant shoot toward light by unequal growth, a response known as phototropism.