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Question #46230
The Question
In a well-stratified forest ecosystem, a shrub exhibits alternate phyllotaxy to minimize self-shading and maximize solar energy capture. Following a severe canopy thinning that alters stratification efficiency, the shrub exhibits developmental plasticity: it shifts from optimal lateral leaf display to rapid, survival-based vertical stem elongation to outcompete neighbors for light. Which of the following correctly identifies the physiological mechanism and the primary Plant Growth Regulator (PGR) driving this domino effect?
Options
- A.
Enhanced apical dominance suppressing lateral bud growth; mediated by Auxins synthesized in the shoot apices.
- B.
Bolting response to rapidly transition into the reproductive phase; mediated by Gibberellins.
- C.
Overcoming of apical dominance to increase the number of phyllotactic nodes; mediated by Cytokinins.
- D.
Stress-induced abscission of lower leaves to conserve metabolic energy; mediated by Abscisic acid.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Phyllotaxy|Stratification Efficiency|Photosynthesis
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between Auxin-mediated apical dominance (vegetative elongation for light competition) and Gibberellin-mediated bolting (reproductive transition).
Students often confuse any stem elongation with Gibberellins, failing to recognize that competitive vertical growth suppressing lateral display is the hallmark of Auxin-driven apical dominance.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Leaf Vernation and Phyllotaxy |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |