How does phototropism occur in plants?
Phototropism is a directional growth movement in plants in response to light. In this process, shoots respond by bending towards light while roots respond by bending away from it.
When growing plants detect light coming from one side, a hormone called auxin is synthesised at the shoot tip. This auxin diffuses towards the shady side of the shoot. The concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light. Thus, the plant appears to bend towards light.
Explanation
The answer explains phototropism as a tropic movement where plant parts show directional growth in response to light. The mechanism involves the hormone auxin, which is synthesised at the shoot tip. When light comes from one side, auxin diffuses to the shady side, causing cells there to elongate more. This differential growth causes the shoot to bend towards the light source. The answer is derived entirely from the textbook context provided.