How does a plant’s root know when to stop growing?

Question

Like when it reaches the wall of a pot. Or, an aerial root has no soil to reach down into, so it dies off?

In: 2

Answer 1

The plant does simply grow, but when it meats an immovable wall, as in the pot, is there no way for it to grow in that direction, and it gets forced to grow in another direction. If a root reaches a place without soil, do the root simply no longer get nutrients from the soil and do simply die.

EDIT Or the root changes from being a root to get a new plant part growing above ground.