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Question #47511
The Question
The evolutionary transition from anoxygenic to oxygenic photosynthesis in early cyanobacteria introduced a severe survival bottleneck due to the release of nascent oxygen and reactive oxygen species (ROS). Which of the following physiological adaptations must have co-evolved simultaneously with the Oxygen Evolving Complex (OEC) to prevent the immediate photo-oxidative destruction of these pioneer organisms?
Options
- A.
Development of the cytochrome b6f complex to bypass Photosystem II via cyclic photophosphorylation
- B.
Synthesis of carotenoids to quench triplet-state chlorophyll and scavenge reactive oxygen species
- C.
Formation of the stratospheric ozone layer to block lethal UV radiation from catalyzing ROS formation
- D.
A structural shift in RuBisCO to completely eliminate its oxygenase activity in the presence of high O2
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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
Phycobilins|Rhodophyceae|Chlorophyceae
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often view the evolution of oxygenic photosynthesis purely as a metabolic upgrade (gaining an abundant electron donor in H2O) without recognizing the immediate lethal consequence of O2 toxicity to early anaerobes.
The trap lies in confusing long-term atmospheric consequences (ozone layer) or metabolic flaws (RuBisCO's oxygenase activity) with the immediate, localized cellular adaptation required for survival (carotenoid synthesis for photoprotection).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Kingdom - Class 11 |
| Concept | Algal Pigmentation Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |