The Question is from neet-botany plant-growth-and-development , and it was created by the author NISHANTH

Question

Which of the following combinations of plant growth regulators are antagonistic in their action on apical dominance?

NISHANTH · Accepted Answer

## CORE INFORMATION
✓ **Answer**: D
## CONCEPT FRAMEWORK
 **Primary Concept**: Apical dominance and the role of plant growth regulators.
 **Related Topics**: Plant hormones, auxin, cytokinin, gibberellin, ethylene, abscisic acid.
 **Prerequisites**: Understanding of plant growth regulators and their effects on plant development.
## SOLUTION PATHWAY
**Given Information**:
The question asks about antagonistic effects on apical dominance.
Apical dominance is the phenomenon where the main, central stem of the plant is dominant over other side stems;  apical buds suppress the growth of lateral buds.
**Method & Steps**:
1. Understand the roles of plant growth regulators:
Auxin promotes apical dominance. It inhibits the growth of lateral buds.
Cytokinin promotes lateral bud growth and inhibits apical dominance.
Gibberellins generally promote stem elongation, but their effect on apical dominance is less direct than auxin and cytokinin.
Ethylene promotes lateral bud growth and can somewhat counteract apical dominance.
Abscisic acid generally inhibits growth.
2. Identify antagonistic pairs:
Antagonistic means opposing or working against each other.  We need a pair where one promotes apical dominance and the other inhibits it.
3. Analyze the options:
Option A (Auxin and Gibberellin): Both promote growth, but their effects on apical dominance are not directly antagonistic.
Option B (Cytokinin and Ethylene): Both promote lateral bud growth, which opposes apical dominance, thus they are synergistic, not antagonistic.
Option C (Gibberellin and Abscisic Acid): These have opposing effects on overall growth, but their specific effects on apical dominance are not directly antagonistic.
Option D (Auxin and Cytokinin): Auxin promotes apical dominance, while cytokinin inhibits it. This is a clear antagonistic relationship.
**Result**: Auxin and Cytokinin are antagonistic in their action on apical dominance.
**Verification**: The roles of auxin and cytokinin in apical dominance are well-established in plant physiology.
## OPTION ANALYSIS
A :x: Auxin and gibberellin both generally promote growth, not directly antagonistic in apical dominance.
B :x: Cytokinin and ethylene both promote lateral bud growth, working synergistically against apical dominance.
C :x: Gibberellin promotes growth while abscisic acid inhibits it; not a direct antagonism regarding apical dominance.
D ✓: Auxin promotes apical dominance, while cytokinin inhibits it, showing a clear antagonistic relationship.
## LEARNING AIDS
 **Common Mistakes**:
  1.Confusing synergistic and antagonistic effects: Understanding the difference between hormones working together and opposing each other is crucial.
  2.Oversimplifying the roles of plant hormones: Plant hormone effects are complex and context-dependent.
 **Quick Tips**:
  1.Remember the key roles: Auxin (apical dominance), Cytokinin (lateral bud growth).
  2.Visualize the plant: Imagine the main stem (auxin) and side shoots (cytokinin) competing for resources.

NISHANTH · Answer

Auxin and Gibberellin

NISHANTH · Answer

Cytokinin and Ethylene

NISHANTH · Answer

Gibberellin and Abscisic Acid

NISHANTH · Answer

The correct Option is "Auxin and Cytokinin"

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