Question

How does Auxin promote the growth of a tendril around a plant.​

Answer 1

Auxin is plant hormone which is synthesized at the tip of the shoot. It helps the cell grow longer. When a tendril comes in contact with a support, auxin stimulates faster growth of the cells on the opposite side that's why the tendril forms a coil around the support.

Answer 2

When the tip of a tendril touches a support , then the auxins present in its tip move to that side of tip which is away from the support . Auxins promote growth . So due to more auxins in it , the side of tendril away from the support grows faster than the side which is in contact with the support and makes the tendril twirl around the support .