GM crops have been developed that are resistant to insect pests. Explain how a gene from another organism could be transferred into a crop plant to produce a genetically modified (GM) crop.

Pearson Edexcel International GCSE Biology (4BI1) — 5.3 Genetic modification (genetic engineering) · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

1. A restriction enzyme cuts the donor DNA to isolate the gene of interest.
2. The gene is inserted into a vector such as a plasmid or viral genome.
3. DNA ligase joins the gene to the vector, forming recombinant DNA.
4. The recombinant vector is introduced into the crop plant cell, where the gene is expressed to give pest resistance.

Examiner tips

  • Use the exact terms: restriction enzyme, vector, ligase, recombinant DNA, expression.
  • Show the four steps in order, each worth one mark.
  • Include the purpose of each component (cutting, carrying, joining, expression).

Common mistakes

  • Confusing restriction enzyme with ligase or vice versa.
  • Omitting the vector step or describing it incorrectly.
  • Failing to mention that the gene is expressed in the plant to give resistance.

Mark scheme (4 marks)

  1. A restriction enzyme is used to cut / isolate the desired gene from the donor organism's chromosome / DNA
  2. A vector (e.g. a plasmid or virus) is used to carry / transfer the gene into the plant cell
  3. Ligase is used to join / seal the desired gene into the vector / plasmid, forming recombinant DNA
  4. The vector / recombinant DNA is transferred into the crop plant cell, so the plant expresses the desired gene / characteristic (e.g. pest resistance)

Key terms in this question

GM crops

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