Question

Read the following statements regarding gibberellins:
A. Gibberellins promote stem elongation.
B. They can induce parthenocarpy.
C. They inhibit seed germination.
Choose the correct answer from the options given below:

• A. Only A and B are correct
• B. Only B and C are correct
• C. Only A and C are correct
• D. A, B and C are correct Correct Answer: (A) Only A and B are correct

Hint:

Think of Gibberellin and Abscisic Acid (ABA) as two bitter rivals fighting a constant tug-of-war inside a seed: - Gibberellin acts as the "Wake-Up" signal that breaks dormancy and starts germination. - ABA acts as the "Sleep" signal that keeps the seed dormant during harsh conditions. Knowing this functional opposition helps you spot incorrect statements about dormancy instantly!

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
Gibberellins represent a vast family of naturally occurring acidic plant hormones (labeled as $\text{GA}_1$, $\text{GA}_2$, $\text{GA}_3$, etc.) that control various aspects of plant development. To evaluate multi-statement hormone questions, you must distinguish between their growth-promoting actions (like axis stretching and tissue manipulation) and their regulatory interactions during a seed's life cycle.

Step 2: Detailed Explanation:
Let's analyze the validity of each statement systematically: - Statement A: "Gibberellins promote stem elongation." (Correct) This is the classic primary function of gibberellins. They increase the length of the axis in plants like sugarcane, grapes, and rosette structures by accelerating cell wall loosening and elongation in internodal tissues. - Statement B: "They can induce parthenocarpy." (Correct) Parthenocarpy is the development of fruits without prior fertilization, resulting in seedless varieties. Gibberellins are highly effective at inducing seedless fruit development in crops like tomatoes, apples, and pears, often performing this role even more effectively than auxins. - Statement C: "They inhibit seed germination." (Incorrect) This statement is factually backward. Gibberellins actually promote and trigger seed germination. When a seed absorbs water, gibberellins are released to activate hydrolytic enzymes (like $\alpha$-amylase). These enzymes break down stored starch into simple sugars to feed the growing embryo, effectively breaking seed dormancy. The hormone that inhibits germination and enforces dormancy is Abscisic Acid (ABA). Since statements A and B are correct, while statement C is incorrect, the correct choice is option (A).

Step 3: Final Answer:
The correct option is (A) Only A and B are correct.