A scientist wants to produce a genetically modified (GM) crop plant that contains a gene for drought resistance from a wild plant species. Describe how the gene for drought resistance could be transferred into the crop plant's genome.

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

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

Model answer (4 marks)

1. Restriction enzymes cut the drought‑resistance gene out of the wild plant’s DNA.
2. The same enzymes cut a plasmid vector to create compatible ends.
3. DNA ligase joins the gene into the plasmid, forming recombinant DNA.
4. The recombinant plasmid is transferred into the crop plant’s cells, where the gene is incorporated into its genome.

Examiner tips

  • Use the word ‘restriction enzymes’ and ‘ligase’ – these are key terms. Show the stepwise transfer: cut, ligate, transfer. Mention the plasmid as the vector. Keep the answer concise – 4 points, one sentence per step.

Common mistakes

  • Using the wrong enzyme name (e.g. polymerase instead of ligase). Omitting the plasmid/vector step. Failing to state that the gene is incorporated into the plant genome.

Mark scheme (4 marks)

  1. Restriction enzymes are used to cut out / isolate the drought-resistance gene from the wild plant's chromosome / DNA
  2. The same restriction enzymes are used to cut open a plasmid (vector)
  3. Ligase is used to join / insert the drought-resistance gene into the plasmid, forming recombinant DNA
  4. The recombinant plasmid (vector) is transferred into the crop plant's cells so the gene is incorporated into the crop plant's genome

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