Question

Leaf abscission is caused by
A. ABA
B. Cytokinin
C. Auxin
D. Gibberellin

Answer 1

Researchers accept that a decrease in daylight prompts the decrease of chlorophyll in the leaf because of a decrease in photosynthesis, and this may trigger the abscission of leaves. The cycle happens when the more fragile cells close to the petiole are pushed off by the more grounded cells underneath them.

Step by step answer: A plant will abscise the leaf and separate it from them. For example, a leaf during fall or a bloom following fertilization or with the end goal of propagation.
Most deciduous plants drop their leaves by abscission before winter, though evergreen plants consistently abscise their leaves. In this way, the right choice is 'ABA'.
-Auxin causes apical growth in plants. So, option C is incorrect.
-Cytokinin causes cell division in the plant cells that help them to grow.
-Gibberellin is a plant hormone that helps in the blooming of flowers.
Hence, option A is correct

Note: Leaf abscission happens at the base of the petiole which is inside set apart by a distinct zone of scarcely any layers of slim walled cells masterminded transitionally over the petiolar base.
This zone is called the abscission zone or abscission layer. The abscission layer separate from one another because of the disintegration of the center lamella. Furthermore, the essential cellulose dividers are affected by the expanded movement of the catalysts pectinase and cellulose.