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Question #47584
The Question
In a heavily industrialized region, dense smog containing suspended particulate matter disproportionately scatters and attenuates blue light (400-500 nm) before it reaches the forest canopy. Which of the following best describes the physiological consequence on the plants' photosynthetic spectra and the corresponding ecological phenomenon?
Options
- A.
The absorption spectrum of Chlorophyll 'a' will undergo a structural shift towards the red wavelengths to maintain the action spectrum, illustrating physiological acclimation.
- B.
The photosynthetic yield in the blue region of the action spectrum will decrease due to reduced photon capture by carotenoids, acting as an environmental selection pressure analogous to industrial melanism.
- C.
Accessory pigments will alter their molecular structure to increase the absorption of green and yellow wavelengths to bridge the spectral gap, demonstrating stabilizing selection.
- D.
The action spectrum will perfectly overlap with the absorption spectrum of Chlorophyll 'b' as it replaces Chlorophyll 'a' as the primary reaction center, driving sympatric speciation.
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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
Action Spectrum|Absorption Spectrum|Industrial Melanism|Carotenoids
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse the 'Absorption Spectrum' (a fixed chemical property of a pigment) with the 'Action Spectrum' (a physiological output that depends on both the pigment's properties AND the environmental availability of specific wavelengths).
The trap relies on the misconception that plants can actively 'shift' their absorption wavelengths to compensate for environmental stress, rather than experiencing a drop in action spectrum efficiency that acts as an evolutionary selection pressure.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Photosynthesis in Higher Plants - Class 11 |
| Concept | Action Spectrum vs Absorption Spectrum |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |