A young seedling was laid on its side in the dark. After two days, the shoot had bent so that it grew upwards, and the root had bent so that it grew downwards.
Name the response shown by the root and the response shown by the shoot.
[2]
In both the root and the shoot, IAA accumulates on the lower side. Explain why this causes the root to bend downwards but the shoot to bend upwards.
[3]
Suggest the survival advantage to the plant of the shoot growing upwards.
[1]