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Question #45316
The Question
To overcome self-incompatibility (SI) in a commercially valuable angiosperm, researchers applied a recombinant peptide—engineered to mimic compatible stigmatic exudates—onto a self-incompatible stigma prior to self-pollination. This intervention resulted in successful fertilization. Which of the following best explains the physiological mechanism and the precise anatomical location of this bypassed barrier?
Options
- A.
The peptide induces a targeted mutation in the S-locus of the pollen grain on the stigmatic surface, genetically transforming it into a compatible male gametophyte.
- B.
The peptide binds to pollen membrane receptors, mimicking a compatible pollen-pistil dialogue and bypassing the S-gene mediated inhibition of pollen germination at the stigma or style.
- C.
The peptide diffuses into the ovary and stimulates the filiform apparatus of the synergids to release chemotropic factors, overriding the incompatibility barrier at the micropyle.
- D.
The peptide acts as an RNase enzyme within the pollen tube, degrading incompatible S-allele transcripts and allowing the vegetative cell to divide in the style.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
S-gene system|Pollen tube|Surface proteins
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Distinguishing between the genetic basis of self-incompatibility (S-alleles) and the phenotypic/chemical execution of pollen-pistil interaction.
Students often confuse chemical signaling bypass (molecular mimicry) with genetic alteration, or they misplace the anatomical site of SI rejection (stigma/style) with later pollen tube guidance mechanisms (filiform apparatus).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Sexual Reproduction in Flowering Plants - Class 12 |
| Concept | Pollen-Pistil Interaction |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |