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Question #46226
The Question
Opuntia possesses a modified photosynthetic stem (phylloclade) adapted to arid environments with high light intensity. Microscopic examination of this stem reveals the absence of Kranz anatomy. Regarding its carbon fixation strategy to mitigate photorespiration, all of the following statements are correct, EXCEPT:
Options
- A.
It employs a temporal separation of initial carbon fixation and the Calvin cycle within the same mesophyll cells.
- B.
RuBisCO operates during the day when stomata are closed, utilizing CO2 released from the decarboxylation of malic acid.
- C.
The initial carboxylation is catalyzed by PEP-carboxylase in the cytoplasm during the night to form a 4-carbon compound.
- D.
It maintains a high intracellular CO2/O2 ratio around RuBisCO by actively transporting malic acid into specialized agranal bundle sheath cells.
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
Stem_Modifications|Kranz_Anatomy_Adaptations|Law_of_Limiting_Factors
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse the mechanisms of C4 and CAM pathways because both utilize PEP-carboxylase and a 4-carbon intermediate to bypass photorespiration.
The trap relies on failing to distinguish between 'spatial separation' (Kranz anatomy, bundle sheath cells in C4) and 'temporal separation' (day/night cycles within the same mesophyll cell in CAM).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Morphology of Flowering Plants - Class 11 |
| Concept | Stem Modifications |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |