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Question #47562
The Question
A researcher grows a C3 plant and a C4 plant in a controlled phytotron with artificially elevated CO2 concentration and negligible O2 levels. Assuming light and temperature are optimal, which of the following statements correctly describes the physiological outcome?
Options
- A.
The C3 plant will exhibit higher energetic efficiency per molecule of glucose synthesized compared to the C4 plant.
- B.
The C4 plant will temporarily suspend the Hatch-Slack pathway and operate exclusively via the Calvin cycle in mesophyll cells.
- C.
RuBisCO in the C4 plant will shift to oxygenase activity due to the absence of evolutionary selective pressure.
- D.
Both plants will require 30 ATP and 12 NADPH to synthesize one molecule of glucose under these conditions.
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
Classification System Nuances|GEAC Oversight|Transgenic Algae
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize 'C4 plants are more efficient than C3 plants' as an absolute rule, forgetting the underlying mechanism.
The trap relies on failing to recognize that the C4 pathway has an inherent energetic cost (12 extra ATP for PEP regeneration).
This cost becomes a metabolic disadvantage when environmental conditions (high CO2/low O2) naturally eliminate photorespiration in C3 plants, rendering the C4 structural advantage redundant.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Kingdom - Class 11 |
| Concept | Classification System Nuances |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |