टॅक पॉलीमरेज हे 'पी.सी.आर्.' मधील महत्वाचे विकर आहे कारण _____

The correct answer is Option B (it is active even at high temperature).

Key Points:
• PCR (Polymerase Chain Reaction) Dynamics:
• Conceived by Kary Mullis in 1983, PCR amplifies specific target DNA segments through thermal cycles involving Denaturation (94-96°C), Annealing (50-65°C), and Extension (72°C).
• Why Taq Polymerase is Unique:
• Standard DNA polymerases denature and lose function at temperatures exceeding 40-50°C.
• Taq polymerase is isolated from the thermophilic bacterium *Thermus aquaticus*, native to geothermal hot springs.
• Its distinguishing characteristic is its thermostability: it withstands repeated thermal exposure at ~95°C without denaturation, enabling automated cycling in a thermocycler without adding fresh enzyme at every cycle.
• Therefore, Option 2 (it is active even at high temperature) is the defining reason for its value in PCR.
• Key Takeaway: Taq polymerase, derived from Thermus aquaticus, is critical in PCR because its extreme thermostability enables survival through high-heat cycles.