Consider the following Assertion (A) and Reason (R) and choose the correct answer using the codes given below :
Assertion (A): Gibberellic acids control seed germination by breakdown of stored food material in monocot seeds.
Reason (R): Gibberellic acid induces the activity of a-amylase from aleurone layer.

Question

Consider the following Assertion (A) and Reason (R) and choose the correct answer using the codes given below : 
Assertion (A): Gibberellic acids control seed germination by breakdown of stored food material in monocot seeds. 
Reason (R): Gibberellic acid induces the activity of a-amylase from aleurone layer.

Accepted Answer

The correct option is 1: Both (A) and (R) are True and (R) is the correct explanation of (A).

The Assertion (A) states that Gibberellic acids (GAs) control seed germination by facilitating the breakdown of stored food material, which is a fundamental biological function of this phytohormone in many plants, especially monocots like barley. Seed germination requires a massive influx of energy to support the growing radicle and plumule, and this energy is stored as insoluble starch in the endosperm. Therefore, mobilizing these reserves into usable sugars is the critical step that GAs enable, making the Assertion factually True. The Reason (R) provides the exact molecular mechanism for this control, stating that Gibberellic acid induces the activity of the enzyme $\alpha$-amylase from the aleurone layer. The aleurone layer, the outermost living layer of the endosperm, is the tissue that perceives the GA signal released by the embryo. In response to GA, the aleurone cells synthesize and secrete $\alpha$-amylase. This enzyme then diffuses into the starch-filled endosperm and hydrolyzes the large starch molecules into simple, transportable sugars (like maltose and glucose). Since the induction of $\alpha$-amylase from the aleurone layer (R) is the precise, direct, and universally accepted mechanism that causes the breakdown of stored food material (A), the Reason correctly explains the Assertion.

The incorrect option is 2: Both (A) and (R) are True but (R) is not the correct explanation of (A).
While both the Assertion and the Reason are independently true biological facts, this option is incorrect because the Reason *is* the direct and correct explanation for the Assertion. The mechanism described in (R)—the induction of the starch-hydrolyzing enzyme, $\alpha$-amylase—is the specific cellular process through which Gibberellic acid achieves the outcome stated in (A), which is the mobilization and breakdown of stored food. To select this option would incorrectly suggest that Gibberellic acid controls germination via stored food breakdown through a different, yet-unidentified pathway, and that the $\alpha$-amylase mechanism is merely a coincidence, which is contrary to established plant physiology.

The incorrect option is 3: (A) is true but (R) is false.
This option is incorrect because the Reason (R) is a factually correct statement. The process of Gibberellic acid (GA) binding to receptors in the aleurone cells, which then initiates a signal transduction cascade that ultimately leads to the expression of the $\alpha$-amylase gene, is a classic and thoroughly documented mechanism in plant hormone research. The massive synthesis and release of $\alpha$-amylase are necessary for the rapid conversion of endosperm starch into sugars, which makes the statement that GA induces this enzyme from the aleurone layer definitively true, thereby invalidating this choice.

The incorrect option is 4: (A) is false but (R) is true.
This option is incorrect because the Assertion (A) is a factually correct statement. Gibberellic acids are one of the most important classes of plant growth regulators involved in breaking seed dormancy and promoting germination, especially in cereal crops. The essential nature of their role is the metabolic shift they initiate, which involves the breakdown of complex carbohydrates (stored food) into simple molecules. This mobilization is what provides the necessary energy and carbon skeletons for the emerging embryo to rapidly grow, confirming the Assertion's truth and making this choice invalid.