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Question #46063
The Question
An ecologist plots the Species-Area Relationship (log S = log C + Z log A) for native submerged macrophytes in a large tropical lake. Following a severe invasion by Eichhornia crassipes that forms a dense mat over the water surface, the ecologist recalculates the SAR for the native macrophytes. Which of the following best describes the expected change in the Z-value (slope of the line) and its primary ecological driver?
Options
- A.
The Z-value decreases (approaches 0); the invasive mat homogenizes the ecosystem, allowing a few native species to uniformly dominate the lake.
- B.
The Z-value increases (becomes steeper); the floating biomass blocks the photic zone, functionally shrinking the habitable niche-area and causing an exponential decline in native biodiversity.
- C.
The Z-value remains unchanged (0.1 to 0.2); the geographical boundaries of the lake are unaltered, and the Z-value is independent of anthropogenic biotic interference.
- D.
The Z-value increases (becomes steeper); the invasive species enhances the biochemical oxygen demand (BOD), thereby expanding the ecological niches for native anaerobic species.
Check Your Answer
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
Ecotone and Edge Effect|Biosphere Reserves Architecture|In-situ Conservation (Hotspots)
Why This Question Is Tricky
Common Mistakes
The 'Conceptual Pivot' is the distinction between 'geographical area' and 'functional ecological area'.
Students commonly memorize NCERT's Z-value ranges (0.1-0.2 for normal areas) as static geographical constants.
The trap is failing to recognize that an invasive species monopolizing a critical resource (light) functionally shrinks the ecosystem, thereby steepening the Z-value due to the accelerated extinction of native species.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biodiversity and Conservation - Class 12 |
| Concept | Evil Quartet Drivers |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |