Question

Name two synthetic auxins. Give four functions of auxins.

Answer 1

Hint: Auxins are the plant hormones that are produced naturally by plants. When sun rays fall on the plant the auxin helps in growth of the plant. Auxins can also be manufactured artificially. Such auxins are known as synthetic auxins.

Complete answer:
Name of two synthetic auxins: 2, 4 - Dichlorophenoxyacetic acid (2, 4-D) and Indole-3-pyruvic acid. Auxins play an important role in the growth and development of plants.

Following are four functions of auxins –
• Stem elongation: Auxins promote elongation of stem. Auxins stimulate gibberellins which results in elongation of cells. This increases the length of the plant. Auxins alongwith gibberellins are responsible for increasing the distance between nodes.
• Growth of seedlings: Auxins control the growth of seedlings by controlling the growth of cells. Auxins are affected by light and they have the tendency to concentrate in plant parts that are away from the light i.e. shaded side. More growth of cells occurs in those parts of the plant which show high concentration of auxins. As auxins are found in more concentration in the shaded side of the plant, the shaded side of the plant shows more growth than parts exposed to light.
• Root initiation: Auxins stimulate the branching of roots. Auxins promote root formations in cuttings. They initiate root formation at the cut when applied to a cut stem.
• Development of fruit: Auxins are responsible for controlling several aspects of fruit development. They help in fertilization, growth and ripening of fruit.

Note: Auxins are the plant hormones that can be natural or synthetic. Natural auxins are produced by plants, while synthetic auxins are prepared in laboratories. Both natural and synthetic auxins perform various functions in plants such as elongation of stem, branching of roots, development of fruit, and growth of seedlings.