Module: | Pollination & Outbreeding Devices
Q40: Consider the following statements regarding the hormonal regulation of seed dormancy:
1. Seed dormancy is solely controlled by the physical hardness and water-impermeability of the seed coat.
2. Abscisic acid (ABA) is a critical endogenous plant hormone that actively induces and maintains a state of seed dormancy.
3. Gibberellic acid (GA) acts antagonistically to ABA, functioning to break dormancy and promote seed germination.
Which of the above statements is/are correct?
2. Abscisic acid (ABA) is a critical endogenous plant hormone that actively induces and maintains a state of seed dormancy.
3. Gibberellic acid (GA) acts antagonistically to ABA, functioning to break dormancy and promote seed germination.
Which of the above statements is/are correct?
✅ Correct Answer: B
The correct option is B. Statements 2 and 3 are correct, whereas Statement 1 is incorrect.
Seed dormancy is a complex evolutionary adaptation ensuring seeds do not germinate under unfavorable conditions.
While structural physical factors like a thick, hard, or impermeable seed coat (exogenous dormancy) do play a role, Statement 1 is false because it ignores the profound internal physiological controls (endogenous dormancy). Causally, the chemical equilibrium between two major phytohormones dictates the seed's state.
Abscisic acid (ABA) is the "stress hormone" that accumulates during seed maturation; it inhibits metabolism, prevents premature germination (vivipary), and locks the embryo in a dormant state.
Conversely, when environmental conditions become optimal, Gibberellic acid (GA) levels rise.
GA directly antagonizes ABA, triggering the synthesis of hydrolytic enzymes (like alpha-amylase) that digest the endosperm, ultimately breaking dormancy and fueling the germinating radicle.
Seed dormancy is a complex evolutionary adaptation ensuring seeds do not germinate under unfavorable conditions.
While structural physical factors like a thick, hard, or impermeable seed coat (exogenous dormancy) do play a role, Statement 1 is false because it ignores the profound internal physiological controls (endogenous dormancy). Causally, the chemical equilibrium between two major phytohormones dictates the seed's state.
Abscisic acid (ABA) is the "stress hormone" that accumulates during seed maturation; it inhibits metabolism, prevents premature germination (vivipary), and locks the embryo in a dormant state.
Conversely, when environmental conditions become optimal, Gibberellic acid (GA) levels rise.
GA directly antagonizes ABA, triggering the synthesis of hydrolytic enzymes (like alpha-amylase) that digest the endosperm, ultimately breaking dormancy and fueling the germinating radicle.