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Question #46224
The Question
In a mutant plant, localized overexpression of Abscisic Acid (ABA) at the nodal regions during the early vegetative phase leads to the premature shedding of dormant axillary buds, compromising stem morphological integrity. Which of the following statements correctly explains the physiological and cellular basis of this premature abscission?
Options
- A.
ABA acts antagonistically to cytokinins by promoting rapid cell division in the abscission layer, mechanically pushing the bud off the stem.
- B.
The localized ABA surge disrupts the basipetal auxin gradient, triggering the synthesis of hydrolytic enzymes that dissolve the middle lamella in the abscission zone.
- C.
The high concentration of ABA at the node enhances the basipetal transport of auxin, which prematurely activates the abscission zone.
- D.
ABA directly inhibits the synthesis of cellulase and pectinase, causing the primary cell wall to harden and mechanically shear the bud.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Stem Morphological Markers|Senescence vs Abscission|Auxin Polarity
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the isolated fact that 'ABA causes abscission' but fail to integrate the systemic mechanism.
The trap lies in understanding that abscission is not just the presence of ABA, but the disruption of the basipetal Auxin gradient, which acts as the primary inhibitor of the abscission zone.
Furthermore, it tests the cellular execution of abscission (dissolution of the middle lamella via hydrolytic enzymes) rather than just mechanical forces.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Stem Morphological Markers |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |