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IB Biology HL 1.1.4 PCR, gel electrophoresis and result interpretation Question Bank

Practise IB Biology HL 1.1.4 by analysing PCR and electrophoresis workflows and interpreting DNA-band evidence.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Analyse how PCR conditions and Taq polymerase produce exponential amplification of a target sequence.
  • Interpret band position or pattern on a gel to evaluate a transformation, match or DNA sample.
  • Evaluate controls and sources of uncertainty in a PCR or electrophoresis experiment.

D1.1.4—PCR and gel electrophoresis question 1

[Maximum number: 1]

The surface antigen gene of hepatitis B virus (HBsAg) was cloned into plant cells using Agrobacterium tumefaciens. Plant cells were selected according to their resistance to kanamycin.

Transformed plant cells were analysed by PCR to see whether they contained the HBsAg gene of 681 base pairs (bp). The image shows the resulting electrophoretic gel with lane 1 showing the reference ladder (size markers), lane 2 a positive control and lane 3 a negative control. Lanes 4 and 5 show the PCR amplification of genomic DNA from transformed plant cells.

Figure for Question D1.1.4—PCR and gel electrophoresis question 1 — IB Biology HL

Using the electrophoretic gel image, deduce with a reason whether the plant cell transformation was successful.

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