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Question #45241
The Question
A researcher subjects mature angiosperm pollen grains to a harsh treatment of boiling water (100°C), concentrated HCl (pH 1.5), and a broad-spectrum protease cocktail. While the internal vegetative and generative cells are completely destroyed, the outer exine remains structurally intact. Which of the following best explains the biochemical basis for the exine's recalcitrance compared to the destroyed cellular contents?
Options
- A.
The exine is composed of highly cross-linked structural proteins that possess a significantly higher thermal denaturation point than vegetative enzymes.
- B.
Sporopollenin is an oxidative polymer of carotenoids and esters, lacking the peptide bonds targeted by proteases and the tertiary structures vulnerable to thermal denaturation.
- C.
The exine is protected by a continuous layer of pectocellulose that competitively inhibits the action of strong acids and proteolytic enzymes.
- D.
Sporopollenin contains specialized chaperone proteins that actively refold the exine matrix upon exposure to extreme physical and chemical stress.
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
Sporopollenin|Pollen_Wall_Chemistry|Protein_Denaturation_Specificity
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize that 'sporopollenin is resistant' but mistakenly assume it is a tough structural protein (like keratin).
The trap exploits the misconception that biological toughness always equals protein cross-linking.
The key to answering is synthesizing the NCERT fact of sporopollenin's absolute resistance with the biochemical principle that all proteins (even tough ones) are eventually susceptible to extreme pH, heat, and proteases, meaning sporopollenin must be a non-proteinaceous polymer (carotenoid/lipid-based).
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biomolecules - Class 11 |
| Concept | Protein Denaturation Specificity |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |