Before You Begin
Question #45934
The Question
An aggressive alien tree species rapidly forms a dense canopy in a tropical forest, drastically reducing the Photosynthetically Active Radiation (PAR) reaching the forest floor. A native shade-tolerant understory shrub now receives light intensity strictly below its light compensation point for an extended period. What will be the immediate physiological consequence and the subsequent survival response of this native shrub?
Options
- A.
Gross Primary Productivity (GPP) equals respiratory losses (R), resulting in zero NPP and a stable, dormant state in the understory niche.
- B.
GPP falls below respiratory losses (R), leading to negative NPP and subsequent leaf abscission to minimize maintenance respiration.
- C.
The plant shifts entirely to cyclic photophosphorylation to generate ATP, bypassing the need for carbon fixation to survive the shade.
- D.
High light attenuation triggers excessive photorespiration, rapidly depleting stored starch and causing immediate root necrosis.
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
Light_Intensity|Interspecific_Competition|GPP_vs_NPP
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating Ecosystem Ecology (NPP = GPP - R) with Plant Physiology (Light Compensation Point).
Students often fail to realize that dropping below the compensation point mathematically forces a negative NPP, and they frequently miss the physiological adaptation of abscission as a mechanism to lower 'R' (respiratory burden) when 'GPP' cannot be increased.
Furthermore, it tests the common misconception that photorespiration occurs in low light.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Respiration in Plants - Class 11 |
| Concept | Compensation Point Logic |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |