Homeostasis

Question 1

How do plants respond to light?

Answer 1

Auxin is produced at the tip of the shoot and in shoots auxin triggers cell growth.

Light causes auxin to concentrate on the darker side of the shoot tip.

Auxin spreads down the shoot

Cells on the darker side grow faster than cells on the lighter side.

This causes the shoot to grow towards the light

Question 2

How to plant roots grow in response to gravity?

Answer 2

Auxin is produced in the toor but gravity causes the auxin to concentrate on the lower side.

In roots auxin inhibits cell growth.

So lower side grows more slowly than the upper side.

It causes the roots to grow towards the force of gravity.