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IB Biology SL D1.1 DNA Replication Question Bank

Practise IB Biology SL D1.1 by explaining replication steps and applying DNA principles to PCR, electrophoresis and profiling.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • explain semi-conservative replication using strand separation, complementary base pairing and phosphodiester bonds
  • distinguish helicase breaking hydrogen bonds from DNA polymerase adding nucleotides to a growing strand
  • apply replication principles to PCR amplification, gel separation and interpretation of DNA profiles

Covered syllabus points

D1.1.1—DNA replicationD1.1.2—Semi-conservative replicationD1.1.3—Role of helicase and DNA polymeraseD1.1.4—PCR and gel electrophoresisD1.1.5—Applications

D1.1 DNA replication question 1

[Maximum number: 1]

What is required to replicate DNA?

A

Temperature of 37∘C37^{\circ} \mathrm{C}

B

Free nucleotides carrying A, C, G and T bases

C

Plasmids

D

Endonuclease

D1.1 DNA replication question 2

[Maximum number: 1]

Meselson and Stahl grew bacteria in a medium with 15 N{ }^{15} \mathrm{~N} (heavy nitrogen) so that all bacteria in the parental culture contain heavy DNA. They then transferred some of the bacteria to a medium with 14 N{ }^{14} \mathrm{~N} (light nitrogen).

Samples were taken at 0,20 and 40 minutes and centrifuged with the results as shown.

Figure for Question D1.1 DNA replication question 2 — IB Biology SL

State the conclusion Meselson and Stahl drew from their experiment.

Up to one additional mark is available for the construction of your answer.

D1.1 DNA replication question 3

[Maximum number: 1]

Outline the role of the following enzymes in replication.

Outline the role of helicase in DNA replication.

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