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Question #47620
The Question
A researcher treats a healthy Zea mays (maize) plant with a specific chemical inhibitor that completely blocks the activity of Phosphoenolpyruvate carboxylase (PEPcase). Assuming the stomata remain open and light reactions are unaffected, which of the following will be the most immediate biochemical consequence?
Options
- A.
Atmospheric will diffuse directly into the bundle sheath cells, allowing the cycle to continue normally without the pump.
- B.
The concentrating mechanism will fail, decreasing the ratio in bundle sheath cells and triggering Rubisco's oxygenase activity.
- C.
Mesophyll cells will immediately upregulate the de novo synthesis of Rubisco to compensate for the inhibited pathway.
- D.
Oxaloacetic acid (OAA) will accumulate in the mesophyll cells due to the cessation of its transport to the bundle sheath.
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
PEP_Carboxylase|Rubisco|Mesophyll_Cells
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the NCERT line 'C4 plants lack photorespiration' as an absolute, structural rule.
This question forces the realization that Kranz anatomy is merely a structural prerequisite; the actual suppression of photorespiration is entirely dependent on the active biochemical pump (PEPcase kinetics).
Without it, Rubisco reverts to its ancestral oxygenase activity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Kranz Anatomy Adaptations |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |