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Question #47522
The Question
In a long-term ecological study, a population of Pinus is subjected to an artificially altered photoperiod. Researchers observe that while both microsporangiate and megasporangiate cones develop normally and wind currents are optimal, the seed set drops to near zero. Which of the following best explains this reproductive failure?
Options
- A.
The temporal synchronization between the dehiscence of microsporangia and the secretion of the pollination drop at the micropyle is lost.
- B.
The altered photoperiod induces the development of a rudimentary ovary wall, physically obstructing the direct access of pollen to the ovule.
- C.
The shift in critical day length prevents the formation of winged pollen grains, rendering anemophily impossible.
- D.
The altered photoperiod inhibits the chemotactic movement of multiflagellate male gametes towards the archegonium.
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
Pteridophyte Heterospory Evolution|Bryophyte Sporophyte Anatomy|Sexual Reproduction Variations
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Phenological Mismatch.
Students often assume reproductive failure must be due to physical barriers, gamete inviability, or structural mutations.
This question tests the understanding that in wind-pollinated gymnosperms, the 'Direct Ovule Access' relies heavily on precise chronological synchronization (timing of the pollination drop).
It also tests taxonomic clarity by using 'ovary wall' and 'multiflagellate gametes' as distractors, which violate the core defining features of Pinus.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Plant Kingdom - Class 11 |
| Concept | Pteridophyte Heterospory Evolution |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |