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Question #46596
The Question
An agricultural field is excessively inoculated with the free-living biocontrol fungus Trichoderma to manage root-borne pathogens. While initially successful, the biocontrol efficacy rapidly declines after a few weeks, accompanied by a sharp drop in the Trichoderma population. Assuming no chemical fungicides were used, which of the following ecological mechanisms best explains this population crash?
Options
- A.
Accelerated catabolism of detritus causes rapid mineralization, depleting the organic substrate reservoir and limiting fungal survival through density-dependent resource depletion.
- B.
Excessive fungal proliferation accelerates humification, creating a humus reservoir that is rapidly consumed by competing soil bacteria.
- C.
The fungal population exceeds the carrying capacity of the grazing food chain, leading to a trophic cascade that limits inorganic nutrient availability.
- D.
The depletion of root pathogens forces Trichoderma to obligately parasitize the plant roots, triggering plant defense mechanisms that eradicate the fungus.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Saprophytes|Fungi|Trichoderma|Nutrient_Cycling
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating 'Microbes in Human Welfare' (Biocontrol by Trichoderma) with 'Ecosystem' (Decomposition steps: Catabolism -> Humification -> Mineralization).
The trap relies on students viewing biocontrol agents purely as 'pathogen killers' while forgetting their fundamental ecological requirement for organic detritus.
Option B serves as a 'Common Half-Truth' trap by testing the NCERT line that humus is highly resistant to microbial degradation, not rapidly consumed.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Microbes in Human Welfare - Class 12 |
| Concept | Biocontrol Agents Synergy |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |