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Question #46933
The Question
While mapping the evolutionary sequence of vascular plants, traditional classification systems often prioritize the presence of vascular tissues (Tracheophyta). However, this creates a taxonomic friction when evaluating heterosporous pteridophytes, as it masks a critical reproductive advancement. Which of the following features in Selaginella represents the exact evolutionary shift that breaks the primitive pattern of an independent prothallus and acts as the precursor to the seed habit?
Options
- A.
The female gametophyte is retained on the parent sporophyte for variable periods, allowing the zygote to develop into a young embryo in situ.
- B.
The germination of heterospores produces a highly reduced, independent, and photosynthetic monoecious prothallus.
- C.
The differentiation of spores into microspores and megaspores completely eliminates the requirement of water for fertilization.
- D.
The dominant sporophyte becomes transiently dependent on the female gametophyte for vascular conduction during early embryogenesis.
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
Systematic Classification Scope|Vascular Evolution Sequence|Pteridophyte Prothallus Nature
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the 'precursor to the seed habit' and the 'true seed habit'.
Students often fall for the trap (Option C) that heterospory eliminates the need for water during fertilization.
In reality, while Selaginella retains the female gametophyte on the sporophyte (Option A - the actual precursor), it still relies on water for fertilization.
Option B traps students who fail to realize heterospory inherently results in dioecious, not monoecious, gametophytes.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | The Living World - Class 11 |
| Concept | Systematic Classification Scope |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |