Describe how selective breeding could be used to produce a new variety of wheat plant that has a higher grain yield.

Pearson Edexcel International GCSE Biology (4BI1) — 5.1 Food production · Describe · 4 marks · View as Markdown

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

Wheat is one of the world's most important food crops. Farmers have used selective breeding for thousands of years to improve the characteristics of crop plants.

Model answer (4 marks)

1. Identify the wheat plants in the existing population that already have the highest grain yield.
2. Cross‑breed (or breed) these selected high‑yield plants together.
3. From the resulting offspring, select those that show the highest grain yield.
4. Repeat steps 1–3 over many generations to increase the frequency of the high‑yield trait in the population.

Examiner tips

Use the word "identify" for step 1, "cross‑breed" for step 2, "select" for step 3 and "repeat" for step 4.
Show the sequence of selection, breeding and repetition clearly.
Use UK spelling (e.g. "breed", "selection").

Common mistakes

Confusing selection with breeding – e.g. saying "breed the best plants" instead of "select the best plants and then breed them".
Omitting the repetition over many generations, which is key to increasing the trait’s frequency.

Mark scheme (4 marks)

Identify/select parent plants with the highest grain yield (from the existing population)
Cross-breed / breed these selected plants together
Select offspring with the highest grain yield from the next generation
Repeat the process over many generations (to increase the frequency of the desired characteristic)

Key terms in this question

selective breeding