Final answer:
Auxins are crucial for the control of apical dominance in plants, while gibberellins stimulate stem elongation. Removing the tip of a plant can demonstrate the role of auxins in lateral bud inhibition and promoting side branch growth. Treating seedlings with gibberellins at different concentrations can show the effect on stem elongation.
Step-by-step explanation:
Auxins are hormones that play a crucial role in plant growth, including the control of apical dominance. Apical dominance refers to the inhibition of lateral bud formation by auxins produced in the apical meristem. This allows the main central stem to grow more strongly than other stems and branches. An experiment demonstrating the role of auxins in apical dominance could involve removing the tip of a plant and observing the subsequent growth of side branches. If the auxins are absent, the lateral buds will start growing.
Gibberellins, on the other hand, are hormones that stimulate stem elongation. This can be demonstrated by treating groups of seedlings with different concentrations of gibberellins and measuring the internode distances. Higher concentrations of gibberellins will result in greater stem elongation. This effect is utilized in agriculture to spray grapes with oversized fruit, as gibberellins promote elongation and enlargement of the fruit.