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IB Biology HL D1.1.4 Pcr and Gel Electrophoresis Questions

Explore PCR temperature cycles, Taq polymerase, DNA-fragment separation and gel-band interpretation in IB Biology HL D1.1.4.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Explain PCR cycles using DNA denaturation, primer annealing and Taq-polymerase extension to amplify a selected DNA sequence.
  • Explain how gel electrophoresis separates DNA fragments by charge and size, and interpret band position or pattern.
  • Use PCR or gel controls, cycle conditions and band evidence to evaluate an amplification or DNA-analysis result.

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Study D1.1.4—PCR and gel electrophoresis conceptsOpen the corresponding Concept lesson for explanations, examples and exam connections.

IB Biology HL D1.1.4 Pcr and Gel Electrophoresis Questions 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 IB Biology HL D1.1.4 Pcr and Gel Electrophoresis Questions 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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