Question

what causes a tendril t encirle or coil around the object in contact with it explain the process involved

Answer 1

This is because of the phytohormone called Auxin.

Auxin accumulates in the region where there is less light.

The place with more concentration of auxin grows longer, thus causing the tendril to encircle

Answer 2

When a part of a plant comes in contact with an object, auxins are diffused to the part of the plant which isn't in the contact with object. This causes rapid growth in that part and results in the formation of a tendril