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Question #47672
The Question
A C_4 plant is treated with a specific metabolic inhibitor that targets mitochondrial isocitrate dehydrogenase. Despite having an active PEP carboxylase anaplerotic pathway to replenish oxaloacetate, the plant exhibits rapid yellowing and premature leaf death. Which of the following best explains this cascading physiological sequence?
Options
- A.
Depletion of alpha-ketoglutarate -> Failure of reductive amination -> Decreased cytokinin synthesis -> Premature senescence
- B.
Inability to regenerate PEP -> Cessation of the C_4 cycle -> Carbon starvation -> Auxin accumulation
- C.
Accumulation of malate in bundle sheath cells -> Osmotic stress -> Abscisic acid overproduction -> Senescence
- D.
Depletion of succinyl-CoA -> Inhibition of the GS-GOGAT cycle -> Ammonia toxicity -> Premature senescence
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
Oxaloacetate|PEP Regeneration Energy Cost|C4 Plants
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating Respiration (amphibolic role of TCA cycle), Mineral Nutrition (reductive amination), and Plant Growth & Development (hormone synthesis).
The common misconception is viewing the TCA cycle solely as an energy-yielding pathway, ignoring its critical role in providing carbon skeletons (alpha-ketoglutarate) for nitrogen assimilation, which is a prerequisite for synthesizing nitrogen-rich hormones like cytokinins.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | TCA Cycle Stoichiometry |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |