Question

_____ is a plant hormone which inhibits growth leading to wilting of leaves.
A. Abscisic acid
B. Gibberellins
C. Auxins
D. Cytokinins.

Answer 1

Hint: Wilting of leaves is the loss of rigidity and is caused when turgor pressure is lignified and reaches zero it happens in the inadequate water supply and is caused by the hormone abscisic acid to prevent water loss.

Complete answer:
To solve this question, at first, we have to know the plant hormone that inhibits the growth leading to wilting of leaves. Plants require sunlight, water, oxygen, minerals for their growth. There are some intrinsic elements that regulate the development and growth of plants. These are known as plant hormones. Plant hormones are chemicals found in very less concentration in plants. They are cytokinins, auxins, gibberellins, abscisic acid and ethylene.

 Now lets us find the solution from given options -
1) Abscisic acid is a sesquiterpene, which has important roles in seed development and maturation, in the synthesis of proteins and compatible osmolytes, which allow plants to tolerate stresses because of environmental or biotic factors, and as a general inhibitor of growth and metabolic activities.
2) Gibberellins are plant hormones that modify various developmental processes, inclusive of stem elongation, germination, dormancy, flowering, flower development, and leaf and fruit senescence.
3) Auxin is a plant hormone produced inside the stem tip that promotes cell elongation. Auxin moves to the darker side of the plant, causing the cells there to develop larger than corresponding cells at the lighter side of the plant.
4) Cytokinins are described as chemical compounds that induce cell proliferation and cause callus differentiation to shoot when applied with auxins, however now it is recognized that cytokinins play a major role in lots of factors of plant growth and development, including of embryogenesis, maintenance of root and shoot meristems.

Thus, the right answer is option A. i.e. Abscisic acid.

Note: Abscisic acid has been found to function in the closing of these stomata during times while the plant no longer requires as much carbon dioxide or during times of drought while the plant cannot afford to lose lots of water through transpiration.