Question

The hormone responsible for apical dominance is

• A. $IAA$
• B. $GA$
• C. $ABA$
• D. florigen

Answer 1

The Correct Option is A

The correct answer to the question of which hormone is responsible for apical dominance is IAA.

Let's explain the concept that underlies this question:

1. Understanding Apical Dominance: Apical dominance is the phenomenon where the main, central stem of the plant is dominant over (i.e., grows more strongly than) other side stems. It is a form of growth control in plants.
2. The Role of Hormones in Apical Dominance: Apical dominance is primarily controlled by the plant hormone auxin, specifically Indole-3-acetic acid (IAA). This hormone is produced in the shoot apex (the tip of the plant) and suppresses the growth of lateral buds, ensuring that the plant grows taller rather than bushier.
3. Explanation of the Given Options:
   • IAA (Indole-3-acetic acid): This is a type of auxin that plays a key role in maintaining apical dominance by inhibiting the growth of lateral buds.
   • GA (Gibberellins): Although involved in stem elongation, seed germination, and other physiological processes, gibberellins do not play a primary role in apical dominance.
   • ABA (Abscisic Acid): This hormone is primarily involved in stress responses, such as the closing of stomata, rather than growth regulation like apical dominance.
   • Florigen: This is a hypothesized hormone responsible for the flowering process and does not relate to apical dominance.
4. Conclusion: Given the role and properties of IAA in promoting apical dominance by suppressing lateral growth, it is the correct answer. The other options do not directly influence apical dominance in the same manner as IAA.