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Question #46291
The Question
A genetically engineered Sorghum plant is developed with an inverted vascular polarity in its leaves, severely disrupting the normal protoxylem-metaxylem arrangement relative to the bundle sheath. Despite possessing fully functional PEP carboxylase and RuBisCO enzymes, the plant exhibits stunted growth and a rapid onset of photorespiration under high light intensity. Which of the following best explains this physiological collapse?
Options
- A.
The spatial disruption of the vascular-sheath interface decouples the transport of C4 acids, failing to maintain a high CO2 concentration around RuBisCO.
- B.
The inverted protoxylem directly degrades the thick, impervious walls of the bundle sheath cells, allowing atmospheric O2 to diffuse in.
- C.
The anatomical inversion forces the primary fixation of CO2 by PEP carboxylase to shift from the mesophyll to the bundle sheath.
- D.
The altered polarity reverses the flow of malic acid, causing decarboxylation to occur in the mesophyll cells instead of the bundle sheath.
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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
Rubisco|Kranz_Anatomy|Protoxylem_vs_Metaxylem|Bundle_Sheath_Cells
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that C4 plants lack photorespiration due to the presence of Kranz anatomy and specific enzymes.
The trap is failing to recognize that Kranz anatomy is fundamentally a spatial and transport-dependent mechanism.
Disrupting the anatomical proximity (vascular-sheath interface) collapses the biochemical CO2 pump, even if all enzymes are perfectly functional.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Protoxylem vs Metaxylem Arrangement |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |