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Question #47608
The Question
Read the following statements regarding the dual functionality of RuBisCO and the evolutionary adaptations in plants. Which of the following statements is INCORRECT?
Options
- A.
The oxygenase activity of RuBisCO is considered an evolutionary relic from an ancient Earth atmosphere that was rich in CO2 and deficient in O2.
- B.
C4 plants completely mitigate photorespiration by replacing RuBisCO with the more efficient PEP carboxylase in the chloroplasts of their bundle sheath cells.
- C.
In C3 plants, the competitive binding of O2 to the active site of RuBisCO leads to the formation of one molecule of phosphoglycerate and one molecule of phosphoglycolate.
- D.
The spatial separation of initial carbon fixation and the Calvin cycle in C4 plants acts as a CO2 concentrating mechanism, ensuring RuBisCO functions primarily as a carboxylase.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Rubisco|Co-evolutionary_Resistance|Evolution
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the 'addition' of a new biochemical pathway with the 'replacement' of an old one.
Because C4 plants lack photorespiration, a common misconception is that they have entirely discarded the 'flawed' RuBisCO enzyme in favor of PEPcase.
In reality, RuBisCO is universally conserved for the C3 cycle; C4 plants merely isolate it spatially in the bundle sheath cells to artificially saturate it with CO2.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Rubisco Dual Functionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |