Practice Test GeeksPCR - Polymerase Chain Reaction Certification Practice Test
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Specimen Collection & Handling 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.

Read the first 7 Specimen Collection & Handling flashcards as text

  1. Which swab type is NOT recommended for collecting respiratory specimens for PCR testing?

    Answer: Calcium alginate swab with wooden shaft

    Calcium alginate and wooden shafts can release substances that inhibit PCR or inactivate viruses.

  2. Which blood collection tube is generally preferred for PCR-based DNA testing?

    Answer: Lavender-top (EDTA)

    EDTA preserves nucleic acids by chelating cofactors needed by nucleases and does not inhibit PCR.

  3. Why are heparinized blood specimens usually avoided for PCR assays?

    Answer: Heparin inhibits DNA polymerase activity

    Heparin binds to the polymerase and nucleic acids, inhibiting amplification.

  4. What is the recommended temperature for long-term storage of specimens intended for RNA testing?

    Answer: -70°C or colder

    Ultra-low temperatures minimize RNase activity and preserve RNA integrity long term.

  5. What is the best practice to avoid nucleic acid degradation from repeated freeze-thaw cycles?

    Answer: Divide specimens into single-use aliquots before freezing

    Aliquoting allows only the needed portion to be thawed, preserving the rest.

  6. What is a primary function of viral transport medium (VTM) in PCR specimen collection?

    Answer: Preserve nucleic acid integrity and suppress bacterial and fungal overgrowth

    VTM contains buffers, protein stabilizers, and antimicrobials to keep the specimen stable.

  7. When collecting a nasopharyngeal swab, how should the swab be inserted?

    Answer: Along the nasal floor, parallel to the palate, until resistance is met

    Inserting parallel to the palate reaches the nasopharynx at about the distance from nostril to ear.

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