Q.4. How do auxins promote the growth of a tendril around a support?
When the tip of tendril touches support, then auxin of that side of the tip is moving away from the side of the support. As we know, auxin promotes growth. So, due to the presence of more auxin in it, the side of tendril away from the support grow longer and faster than the support side.
And due to this type of growth, it makes the tendrils bend around the support.