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Question #47759
The Question
To maintain the genetic integrity of an endangered plant species in a seed bank (ex-situ conservation), researchers amplify specific molecular markers using PCR prior to downstream sequencing. However, the final sequenced data reveals a 'genetic mosaic', indicating the extensive amplification of non-target contaminant DNA alongside the target sequence. Which of the following procedural errors most likely compromised the stringency of this process?
Options
- A.
The annealing temperature was set significantly lower than the optimal melting temperature of the primers.
- B.
Chilled ethanol was utilized during the downstream precipitation of the extracted DNA.
- C.
The initial denaturation step was executed at 94 degrees Celsius rather than 72 degrees Celsius.
- D.
Taq polymerase was used during the extension phase, leading to errors due to its lack of 3' to 5' exonuclease proofreading activity.
Check Your Answer
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
Taq Polymerase|Ethidium Bromide Visualization|Gel Electrophoresis Migration
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Understanding the thermodynamic concept of 'stringency' in PCR annealing.
Students often memorize the PCR temperatures (94, 54, 72) without understanding that lowering the annealing temperature reduces specificity, allowing primers to bind to non-target DNA.
Common Misconception: Students might choose Option D, confusing the micro-level point mutations caused by Taq polymerase's lack of proofreading with the macro-level non-target amplification caused by low primer stringency.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Biotechnology : Principles and Processes - Class 12 |
| Concept | Taq Polymerase Thermal Stability |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |