Question

What is the role of auxin?
A. Prevents abscission of leaves and fruits
B. Promotes abscission of leaves and fruits
C. Promotes stomatal closure
D. promotes dormancy

Answer 1

Hint: Young leaves and fruits make auxin at that time they remain connected to the stem. When the range of auxin decreased, a specific portion of cells called the abscission layer which produces at the bottom of the petiole. As soon the petiole or fruit stalk falls free at this end and the leaf or fruit falls to the ground.

Complete Answer:
- Auxin is a plant hormone which helps in stem development, stop growth of lateral buds.
- Auxin goes to the dark portion of the plant which causes the cells there to grow bigger than the corresponding cells on the light portion of the plant.
- This develops a curving of the plant stem tip toward the sunlight, a plant movement called phototropism.
- Auxin is a plant hormone. It is associated with many physiological processes of plants. It acts as a plant growth promoter. It prevents abscission of leaves and fruits. It prevents premature fall of leaves and fruits. Its concentration is low in mature fruits and leaves.

Thus, the correct option is A. i.e. Prevents abscission of leaves and fruits.

Note: Auxin also plays a role in maintaining apical dominance. Most plants have lateral (sometimes called axillary) buds located at nodes (where leaves attach to the stem). Auxin controls the dormant state in bud. As long as enough auxin is formed by the apical meristem, the lateral buds rest dormant. If the shoot apex is replaced, the auxin is not formed. That will result in the lateral buds to interrupt their dormancy and start to grow.