Practice Questions

1.Describe how auxin causes a shoot to bend towards light.

Auxin is produced in the shoot tip. When light shines on the plant from one direction, auxin moves to the shaded side of the shoot. In shoots, auxin stimulates cell elongation. The cells on the shaded side grow longer than the cells on the light side. This causes the shoot to bend towards the light.

2.A scientist removes the tip of a plant shoot.
Predict what will happen to the plant’s growth and explain why.

Auxin is produced in the shoot tip. If the tip is removed, the plant cannot produce auxin. Without auxin, there is no movement of auxin to the shaded side and no unequal cell elongation. This means the shoot cannot bend towards light and growth is reduced.

3.State two roles of ethene in plants.

Controls fruit ripening

Controls cell division