Which of the following is NOT a possible reason for false negative PCR results?

The correct answer is that excessive heat during amplification is not a possible reason for false negative PCR results. In PCR (Polymerase Chain Reaction), the cycling process requires high temperatures to denature DNA, allowing the strands to separate and enabling primers to bind to the target sequences. While inadequate temperature control might affect the efficiency of amplification, generally, the PCR process is designed to overcome issues related to temperature by utilizing specific enzymes, like Taq polymerase, that are heat-stable and function optimally at high temperatures.

On the other hand, the other options are common factors that can lead to false negative results. For instance, the presence of amplification inhibitors can interfere with the enzymatic activity during PCR, preventing the target sequence from being properly amplified. Mutations that occur beneath the primer binding site can render the primers unable to bind effectively, which leads to a lack of amplification. Similarly, if the nucleic acid samples are degraded, the fragments may be too short or damaged for effective amplification, resulting in a failure to detect the target DNA. Understanding these potential pitfalls is crucial for optimizing PCR results and ensuring accurate detection in molecular diagnostics.