Polymerase Chain Reaction (PCR) Quiz – Part 3: Quantitative & Real-Time PCR

Attempt all 10 questions. Click Submit to check your score and correct answers.

21. The annealing temperature in PCR is usually:

a) 20–30°C
b) 50–65°C
c) 90–95°C
d) 100°C

22. The extension step of PCR using Taq polymerase typically occurs at:

a) 37°C
b) 50°C
c) 72°C
d) 95°C

23. The purpose of magnesium ions (Mg²⁺) in PCR is to:

a) Stabilize DNA duplex
b) Act as a cofactor for DNA polymerase
c) Denature DNA
d) Inhibit nonspecific binding

24. Which parameter is MOST critical for primer design?

a) Primer length
b) GC content
c) Melting temperature (Tm)
d) All of the above

25. In qPCR, the cycle threshold (Ct) value is:

a) The number of cycles where amplification starts
b) The number of cycles at which fluorescence exceeds background
c) Always 40 cycles
d) The melting point of primers

26. A lower Ct value in qPCR indicates:

a) Lower template concentration
b) Higher template concentration
c) Primer dimer formation
d) Failed amplification

27. Which method in qPCR uses fluorescent probes specific to the target sequence?

a) SYBR Green method
b) TaqMan assay
c) Gel electrophoresis
d) Southern blot

28. The efficiency of PCR amplification ideally should be:

a) 50%
b) 75%
c) 90–110%
d) 200%

29. Which plot is used in qPCR to determine amplification efficiency?

a) Melt curve
b) Standard curve
c) Growth curve
d) Calibration curve

30. Melt curve analysis in qPCR helps to:

a) Confirm specificity of amplification
b) Determine Mg²⁺ concentration
c) Measure extension rate
d) Quantify template directly

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