Question

What is the role of Gibberellic acid in plants?

• A. It promotes cell division and elongation in stem tissues.
• B. It increases the levels of anti-oxidants
• C. It decreases the levels of plant growth hormones.
• D. It inhibits the synthesis of plant secondary metabolites.

Hint:

Associate each major plant hormone with its "headline" function:

\textbf{Auxin:} Apical dominance, tropisms, cell elongation.
\textbf{Gibberellin:} Stem elongation, seed germination.
\textbf{Cytokinin:} Cell division (cytokinesis), anti-aging.
\textbf{Abscisic Acid (ABA):} Dormancy, stress response (stomata closure).
\textbf{Ethylene:} Fruit ripening, senescence.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The question asks for a primary role of Gibberellic Acid (GA), which is one of the five major classes of plant hormones.
Step 2: Detailed Explanation:
Gibberellins are a group of plant hormones with a wide range of functions, but their most prominent effects are related to growth and development.

Stem Elongation: This is the most dramatic and well-known effect of GA. It stimulates internodal elongation in stems, causing plants (especially genetic dwarf varieties) to grow tall. This effect is achieved by stimulating both cell division in the apical meristem and the subsequent elongation of those cells.
Seed Germination: GAs break seed dormancy and promote germination by stimulating the production of hydrolytic enzymes (like \(\alpha\)-amylase) in the aleurone layer of cereal grains.
Flowering and Fruit Development: GAs can induce flowering in some plants (bolting in long-day plants) and are involved in fruit set and growth.
Let's evaluate the given options:

(A) It promotes cell division and elongation in stem tissues: This accurately describes the primary mechanism by which gibberellins cause stem elongation.
(B) It increases the levels of anti-oxidants: While hormonal changes can affect a plant's stress response, this is not a primary, defining role of GA.
(C) It decreases the levels of plant growth hormones: GA is itself a major plant growth hormone and often acts synergistically with others, like auxins. This statement is incorrect.
(D) It inhibits the synthesis of plant secondary metabolites: This is incorrect. The biosynthesis of gibberellins is itself a complex metabolic pathway, and its effects on other secondary metabolites are varied, not simply inhibitory.
Step 3: Final Answer:
The most accurate and primary role of Gibberellic acid listed is the promotion of cell division and elongation in stem tissues.