Practice Test GeeksPCR - Polymerase Chain Reaction Certification Practice Test
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Quality Assurance & Control Flashcards

7 cards from real PCR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. A no-template control (NTC) shows amplification at Ct 31 in a qPCR run. What is the most likely interpretation?

    Answer: Reagent or environmental contamination is present

    Amplification in an NTC indicates template contamination of reagents, consumables, or the workspace.

  2. In a diagnostic PCR run, the positive control fails to amplify while all patient samples are negative. What should the technologist do?

    Answer: Invalidate the run and repeat testing

    A failed positive control means the assay cannot be shown to work, so negative results are unreliable and the run is invalid.

  3. What is the main purpose of an internal amplification control (IAC) spiked into each sample?

    Answer: To identify false negatives caused by inhibition or reaction failure

    An IAC amplifies in every valid reaction, so its failure flags inhibition or reaction failure that could cause a false negative.

  4. On a Levey-Jennings chart, a single control value falls outside ±3 SD of the mean. Which Westgard rule is violated?

    Answer: 1-3s

    The 1-3s rule rejects a run when one control value exceeds the mean ±3 SD, usually pointing to random error.

  5. Two consecutive control results both exceed +2 SD on the same side of the mean. This pattern most likely reflects:

    Answer: Systematic error such as a reagent or calibration shift

    Violating the 2-2s rule points to systematic error, such as a reagent lot or calibration shift.

  6. A negative extraction control (extraction blank) carried through nucleic acid isolation is designed to detect:

    Answer: Contamination introduced during the extraction process

    An extraction blank goes through every extraction step, so amplification in it shows contamination was introduced during extraction.

  7. Which enzymatic system is used to destroy carryover amplicons from previous PCR reactions?

    Answer: Uracil-N-glycosylase (UNG) with dUTP incorporation

    Incorporating dUTP into amplicons lets UNG degrade any carryover product before the next PCR's amplification begins.

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