Question

If you cover the tip of a shoot in opaque black aluminium foil, towards which direction does the shoot grow? Or does it even grow at all?

This topic is about tropisms and auxins, thanks.

Answer 1

It will grow upward as auxin is uniformly distributed around the tip of the plant.

Explanation:

Auxin is naturally produced by the tips of the plants and it helps them elongate. Auxin escapes light making the area in the shade elongate more so the plant tip moves towards the light. Since the plant tip is covered, then the produces auxin will be uniformly distributes enabling the tip to grow upwards. It grows up because auxin has another role in shoots which growing away from the gravity. This kind of response is called negative geotropism.