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Question #46826
The Question
Native dicot trees often suffer catastrophic ecological collapse when exposed to alien wood-boring pathogens, despite possessing a well-developed heartwood. Contrastingly, native pathogens rarely cause such mass mortality. Which of the following best explains this phenomenon, integrating plant anatomy and evolutionary biology?
Options
- A.
Heartwood contains living ray parenchyma cells that actively secrete phenolic compounds against native threats, but these cells are rapidly lysed by alien pathogens.
- B.
Native trees lack the co-evolved genetic history to synthesize specific secondary metabolites against novel alien pathogens, bypassing the passive chemical defense of the dead heartwood.
- C.
Alien pathogens dissolve the suberin strips in the heartwood's endodermis, restoring water conduction and allowing the pathogen to spread systemically.
- D.
While industrial melanism is a phenotypic plasticity response to pollution, heartwood formation is a directional evolutionary shift that is ineffective against alien 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
Heartwood|Alien Species Invasion Impacts|Industrial Melanism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: This question tests the synthesis of Plant Anatomy and Evolutionary Ecology.
The primary trap relies on students anthropomorphizing plant defenses (assuming heartwood provides an 'active' living immune response like animal cells) and confusing anatomical locations (placing endodermis in secondary xylem).
It also tests the fundamental mechanism of Industrial Melanism, ensuring students distinguish between genetic natural selection and phenotypic plasticity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Anatomy of Flowering Plants - Class 11 |
| Concept | Heartwood vs Sapwood |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |