Question

what is phototropism .How does it occurs

Answer 1

The directional movement of a plant in response to light is called phototropism. The shoot responds by bending towards light and roots respond by bending away from light.
This happens as follows:
(i) When sunlight falls straight on the plant, the auxin hormone synthesised at the tip of the stem spreads uniformly down the stem and due to equal concentration of auxin, stem grows straight.
(ii) When sunlight fells on only one side of the plant, the auxin diffuses towards the shady side of shoot. The concentration of auxin stimulates the cells to grow longer. Therefore, the stem appears to bend towards the source of light.

Answer 2

The movements of parts of plant in the direction of sunlight is called phototropism.It is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light have a chemical called auxin that reacts when phototropism occurs. This causes the plant to have elongated cells on the farthest side from the light.
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