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Question #47512
The Question
When a culture of unicellular green algae is subjected to prolonged, high-intensity UV radiation, a marked decline in carbon assimilation is observed despite optimal CO2 and water availability. Based on the principles of photoprotection and cellular metabolism, which of the following statements regarding this stress response is INCORRECT?
Options
- A.
Carotenoids mitigate oxidative stress by quenching singlet oxygen, thereby protecting the reaction centre chlorophyll a from photo-oxidation.
- B.
High UV exposure compromises nucleic acid stability, triggering energy-expensive DNA excision repair pathways that consume ATP.
- C.
UV radiation directly induces structural mutations within the carotenoid molecules, permanently altering their light-harvesting action spectra.
- D.
The systemic metabolic depression reflects a homeostatic shift where energy allocation for maintaining DNA integrity supersedes photosynthetic yield.
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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
Bacteriochlorophyll|Oxygenic_Photosynthesis|Stromatolites
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The trap exploits the misuse of the term 'mutation'.
Students often loosely associate UV damage with 'mutation' across all cellular components.
However, mutation is a genetic principle strictly applicable to nucleic acids, not to biochemical metabolites or pigment molecules like carotenoids.
Furthermore, it tests the synthesis of Class 11 Chapter 13 (Photosynthesis - photoprotection by accessory pigments) and Class 12 Chapter 6 (Molecular Basis of Inheritance - UV as a mutagen).
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 |