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Question #46023
The Question
During primary succession on a bare rock (xerarch succession), pioneer species like lichens initiate pedogenesis. Suppose a continuous influx of atmospheric pollutants irreversibly inhibits the extracellular enzymes of the local microbial decomposers. Which of the following represents the most critical bottleneck that will permanently arrest the successional progression?
Options
- A.
Failure of fragmentation by detritivores, leading to an immediate collapse of the pioneer lichen community.
- B.
Arrest of humification and catabolism, preventing the formation of the organic soil reservoir required by subsequent seral stages.
- C.
Accelerated mineralization of inorganic nutrients, causing heavy metal toxicity that prevents the establishment of bryophytes.
- D.
Inability of the pioneer lichens to secrete organic acids, halting the chemical weathering of the underlying bedrock.
Check Your Answer
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
Lichen|Humification|Secondary_Productivity|Decomposition
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'lichens make soil by weathering rock' but fail to integrate the Decomposition cycle (Chapter: Ecosystem) with Succession.
The trap assumes students might confuse the physical/chemical weathering by pioneer species (acid secretion) with the biological decomposition of those pioneers required to form mature organic soil (humification).
Option D is a classic distractor testing this exact functional overlap.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Ecosystem - Class 12 |
| Concept | Ecological Succession Climax |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |