Quiz  /  PCR Class 12 MCQ Questions With Answers

  • 1. 
    At what temperature does annealing of primers take place in PCR?

  • 50 - 65oC
  • 94oC
  • 37oC
  • 72oC

  • 2. 
    At what temperature does denaturation take place in PCR?

  • 50 - 65oC
  • 94oC
  • 37oC
  • 72oC

  • 3. 
    Why must annealing of primers take place at between 50 - 65oC?

  • To prevent Taq polymerase from denaturing, allowing it to catalyse the binding of primers to the target gene.
  • To ensure that primer annealing happens quickly - higher rate of reaction as temperature is high.
  • To allow the formation of hydrogen bonds between the primer and target gene.
  • To prevent the formation of hydrogen bonds between the primer and target gene.

  • 4. 
    DNA replication results in

  • 2 completely new DNA molecules
  • 2 DNA molecules that each contain a strand of the original DNA molecule
  • 1 new DNA molecule and 1 original DNA molecule
  • 2 DNA molecules, each with original and new parts of DNA interspersed

  • 5. 
    During PCR, what is the purpose of increasing temperature to 95 °\degree° C?

  • For primers to anneal to DNA template strands
  • To separate DNA strands
  • To denature Taq polymerase
  • For Taq polymerase to form new copies of DNA

  • 6. 
    Replication proceeds in a ____ to _____ direction.

  • 3' to 5'
  • 3' to 3'
  • 5' to 3'
  • 5' to 5'

  • 7. 
    Which of the following best describes the role of primers?

  • Frame the beginning and end of the target sequence
  • Copy the DNA
  • Cause DNA strands to separate
  • Heat the sample

  • 8. 
    At what temperature does the Denature step of PCR occur?

  • 94-96° C
  • 50-65° C
  • 72° C
  • Any temperature

  • 9. 
    What are the base-pairing rules in DNA?

  • A-C, G-T
  • A-U, G-C
  • A-T, G-C
  • A-C, G-U

  • 10. 
    During PCR annealing phase, primers are able to

  • bind to random sequences
  • bind to complementary DNA sequences
  • bind to exactly the same DNA sequences
  • bind to antisense DNA

  • 11. 
    [Bonus!] You decide to use PCR to determine if you have the allele for cystic fibrosis, a genetic disorder. You then decide to also check if you have the allele of a different gene that puts you at risk for developing Alzheimers disease.What PCR "ingredient" would be different in these two tests?

  • Template DNA
  • Nucleotides
  • Taq DNA polymerase
  • Primers

  • 12. 
    Starting with 15N15N (heavy) DNA, and after one generation in the 14N medium, Escherichia coli cells will contain

  • all 15N14N (hybrid) DNA.
  • half 15N15N DNA (heavy) and half 14N14N DNA (light).
  • half 14N14N (light) DNA and half 15N14N (hybrid) DNA.
  • all 14N14N (light) DNA.

  • 13. 
    You decide to use PCR to determine if you have Cystic Fibrosis, a genetic disorder. You then decide to also check if you are at risk for developing Alzheimers, another genetic disorder.What PCR "ingredient" would be different in these two tests?

  • Template DNA
  • Nucleotides
  • Taq DNA polymerase
  • Primers

  • 14. 
    What does PCR stand for?

  • Polymerase Chronic Reagent
  • Principle Chorionic Reliability
  • Polymerase Chain Reaction
  • Probably Cannot React

  • 15. 
    From where does Taq polymerase come?

  • Bacteria that live in hydrothermal vents/hot springs.
  • Cambodia
  • The rain forest
  • The CDC

  • 16. 
    The enzyme ________ unwinds and unzips the DNA double helix.

  • DNA polymerase
  • Helicase
  • DNA ligase
  • Topoisomerase

  • 17. 
    Which scientists proved that DNA replication is semi-conservative?

  • Hershey and Chase
  • Watson and Crick
  • Meselson and Stahl
  • Franklin and Wilkins

  • 18. 
    How many cycles of PCR does it take to produce a double-stranded DNA fragment of the desired length?

  • 1
  • 2
  • 3
  • 4

  • 19. 
    Which of the following best describes the role of primers in PCR?

  • Frame the beginning and end of the target sequence
  • Copy the DNA
  • Cause DNA strands to separate
  • Heat the sample

  • 20. 
    Why does PCR require a specific type of polymerase?

  • Taq polymerase can withstand the range of temperatures in PCR without denaturing.
  • Taq polymerase is the most inexpensive type of polymerase.
  • Taq polymerase is the most common type of polymerase.
  • A specific type of polymerase is unnecessary.

  • 21. 
    With regards to DNA replication along the template strand, what event takes place first?

  • DNA polymerase begins adding RNA nucleotides
  • DNA polymerase begins adding DNA nucleotides
  • DNA ligase joins the Okazaki fragments
  • primase adds an RNA primer

  • 22. 
    What is the purpose of the Extension step of PCR?

  • To create the primers.
  • To extend the time it takes to produce DNA.
  • To allow polymerase to create the complementary strands of DNA.
  • To allow substrates to copy DNA sequences.

  • 23. 
    What type of bonds hold the two strands of DNA together?

  • Hydrogen bonds
  • Covalent bonds
  • Dipole-Dipole bonds
  • Ionic bonds

  • 24. 
    What is the best definition for "dNTP"

  • A nitrogenous base bound to a 5 carbon sugar with 3 phosphate groups bound to the sugar.
  • A nitrogenous base bound to a 5 carbon sugar.
  • The generic name for a nucleotide base.
  • The generic name for a nucleoside base.

  • 25. 
    How many cycles of PCR are normally used.

  • 20-35
  • 6
  • 45
  • 100
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