Question

how do auxin promote the growth of tendrils around a support​

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 tendrils come in contact with any support, the tip of tendril in contact with the object does not grow as rapidly as a part of a tendril away from the object this is due to the fact that auxin secreted in the tip diffuses towards the side of opposite to the point of contact . So this induces more growth on the side opposite to the point of contact . Thereby causing the central to circle around the object.