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Question #46015
The Question
In a mature terrestrial ecosystem, an environmental shift causes the accumulated leaf litter to become exceptionally rich in lignin and chitin, significantly increasing the C:N (Carbon to Nitrogen) ratio of the detritus. Which of the following will be the most direct and immediate consequence on the ecosystem's nutrient cycling?
Options
- A.
Accelerated mineralization of the detritus, leading to an immediate spike in Gross Primary Productivity (GPP).
- B.
Enhanced nutrient immobilization by soil microbes, causing a temporary depletion of available soil nutrients and a decline in Net Primary Productivity (NPP).
- C.
Rapid leaching of inorganic nutrients into the lower soil horizons, permanently decoupling the Detritus Food Chain (DFC) from the Grazing Food Chain (GFC).
- D.
Increased rate of humification due to the high nitrogen demand of saprotrophs, resulting in highly fertile topsoil.
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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
Detritus Food Chain Dominance | Decomposition Rate Modifiers | Nutrient Cycling Reservoirs
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: The dual role of microbes in nutrient cycling.
Students often assume decomposers always immediately release nutrients (mineralization).
However, when faced with high lignin/chitin (recalcitrant detritus), microbes act as nutrient sinks (immobilization), outcompeting plants for available soil nitrogen and creating a negative feedback loop on primary productivity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Ecosystem - Class 12 |
| Concept | Detritus Food Chain Dominance |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |