Question

Which of the following generally act as an antagonist to gibberellins?
A. Zeatin
B. Ethylene
C. ABA
D. IAA

Answer 1

Hint: In order to start answering the questions, we must first understand the properties and functions of each of the plant hormones mentioned below. Moreover, we must also know what is the specific function of gibberellins in the plant system.

Complete answer:
The hormones mentioned above have the following effect in the plant system
1.Gibberellins-They cause elongation of internodes, increased leaf growth and apical dominance. They also promote stem elongation and germination.
2.Zeatin-Helps in the growth of lateral buds and formation of bushy plants.
3.Ethylene-Helps promote the growth and senescence of plants depending on its concentration and timing.
4.ABA( Abscisic Acid)-It plays a major role in many developmental processes of plants. Controls the dormancy of seeds and buds along with organ size
5.IAA-It is the main auxin in plants, regulating growth and developmental processes such as cell division and elongation, tissue differentiation, apical dominance, and responses to light, gravity, and pathogens. Roots are most sensitive to fluctuations in IAA level.
 Abscisic Acid and gibberellins are antagonistic to each other. Abscisic Acid promotes dormancy of seeds however gibberellins promote germination of seeds.

Thus, the correct option is (C) ABA.

Note:
Plant hormones are of immense importance in the growth and development of plants. Although it is the metabolism of the nutrients that the plants receive that helps it to synthesize those essential building blocks, it is the plant hormones that ultimately regulate the velocity of growth and many other factors that make up a healthy plant that we see. These plant hormones work to regulate important plant processes.