Question

State how concentration of auxin stimulates the cells to grow longer on the side of the shoot which is away from light ????

Answer 1

When growing plants detect light, a hormone called auxin, synthesised at the shoot tip, helps the cells to grow longer. When light is coming from one direction of the plant, auxin diffuses towards the shady side. This 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.

Answer 2

Auxin is a hormone that synthesizes at the top of the shoot and helps cells grow longer when plants growth. When light falls on the  shoot side, auxin spreads to the dark (shady) side of the shoot. This auxin concentration stimulates the cell to grow longer on the dark shoot side so that the plant seems to bend to the light.