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Question #45953
The Question
In many orchids, the seeds are microscopic, lack an endosperm, and exhibit an obligate dependency on mycorrhizal fungi to form a protocorm. Which of the following statements regarding the interaction between the orchid's meristematic tissue and this symbiotic fungus is INCORRECT?
Options
- A.
A. The fungal hyphae provide essential carbohydrates, acting as a physiological trigger to break the dormancy of the shoot apical meristem.
- B.
B. Despite possessing inherent cellular totipotency, the orchid embryo cannot initiate cellular proliferation without the symbiotic fungal colonization.
- C.
C. The mycorrhizal association is facultative during the early protocorm stage but becomes obligate once the shoot apical meristem differentiates into mature photosynthetic leaves.
- D.
D. The symbiotic loop compensates for the absence of seed storage reserves, bypassing the 'seedling block' to sustain early meristematic activity.
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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
Meristematic Totipotency|Mycorrhiza Nutrient Dynamics|Feedback Mechanism Loops
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often confuse the timeline of symbiotic dependency.
They assume that because mature plants have mycorrhizae for mineral absorption, the dependency increases as the plant grows.
In orchids, the dependency for carbon is absolute (obligate) at the seed/protocorm stage due to the lack of endosperm, and decreases once the plant becomes autotrophic.
Furthermore, it tests the misconception that 'totipotency' equals 'developmental autonomy'—totipotent cells still require specific external nutritional and hormonal inputs to manifest their potential.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Growth and Development - Class 11 |
| Concept | Meristematic Totipotency |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |