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Question #46243
The Question
In a xerophytic plant where leaves are entirely modified into spines to minimize transpiration, a systemic fungal toxin competitively inhibits the enzyme succinate dehydrogenase. Shortly after infection, the plant rapidly undergoes cellular desiccation despite adequate soil moisture. Which of the following best explains the primary physiological cause of this desiccation?
Options
- A.
The inability to oxidize succinate to fumarate halts FADH2 production, depriving the ETC of electrons and ceasing the formation of metabolic water at Complex IV.
- B.
The toxin forces the irreversible opening of sunken stomata on the photosynthetic stem, leading to massive transpirational water loss.
- C.
The accumulation of succinate lowers the water potential of the mitochondrial matrix, causing rapid exosmosis and plasmolysis of the cortical cells.
- D.
The toxin directly inhibits the photolysis of water in the thylakoid lumen, depriving the plant of the internal water required to maintain cellular turgor.
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
Leaf Modifications|TCA Cycle Stoichiometry|Metabolic Water Formation
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently forget that cellular respiration produces water (metabolic water) at the end of the ETC, while photosynthesis consumes water via photolysis.
Furthermore, this question tests the ability to link a micro-biochemical pathway (TCA cycle stoichiometry and Complex II inhibition) to a macro-ecological adaptation (xerophytic reliance on metabolic water due to the absence of a strong transpiration stream).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Leaf Modifications |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |