Selective breeding has been used to produce wheat plants with a higher grain yield. Describe how a farmer would carry out selective breeding over several generations to produce a wheat variety with a consistently high grain yield.

Cambridge International IGCSE Biology (0610) — 18.3 Selection · 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. Identify the wheat plants in the current crop that produce the greatest grain yield.
2. Cross‑breed (interbreed) those high‑yield plants to produce the next generation.
3. Grow the offspring and select the individuals that again show the highest grain yield.
4. Repeat steps 2–3 over many generations until the high‑yield trait becomes stable and consistent.

Examiner tips

  • Use the word ‘identify’ for the first step, ‘cross‑breed’ for the second, and ‘select’ for the third.
  • Show the cycle of selection and breeding clearly; examiners look for the repeated process.
  • Mention that the goal is a stable, consistently high yield trait.
  • Keep the answer concise – 4 marks only.

Common mistakes

  • Confusing ‘select’ with ‘breed’ in the same step.
  • Failing to state that the process is repeated over many generations.
  • Using vague terms like ‘improve’ instead of the specific actions required.

Mark scheme (4 marks)

  1. Identify and select wheat plants that show the highest grain yield from the existing population.
  2. Breed the selected plants together (cross-pollinate / interbreed the chosen plants).
  3. Select offspring that show the highest grain yield from the next generation.
  4. Repeat the process of selection and breeding over many generations until the trait is consistent / stable.

Key terms in this question

selective breeding · generations

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