Explain how selective breeding could be used to develop a new variety of wheat that produces a higher yield of grain.

Edexcel GCSE Biology (1BI0) — 4.3 Selective breeding and genetic engineering · Explain · 4 marks · View as Markdown

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

Farmers in the UK are looking to increase food production. One approach involves selectively breeding wheat plants over several generations to obtain a variety that consistently produces more grain per plant than current varieties.

Model answer (4 marks)

Select wheat plants that naturally produce the highest grain yield and use them as parents.
Cross‑breed these selected plants (or allow them to self‑fertilise) to produce offspring.
From the offspring, select those that give the highest grain yield and breed them again.
Repeat this selection and breeding over many generations until a wheat variety with a consistently higher yield is established.

Examiner tips

Use the word ‘select’ and ‘breed’ to show the process. Show the cycle of selection → breeding → repeat. Mention that the desirable trait becomes fixed in the population.

Common mistakes

Confusing selection with random breeding. Failing to state that the process is repeated over many generations. Using vague terms like ‘improve wheat’ without describing the steps.

Mark scheme (4 marks)

Select wheat plants that naturally produce the highest yield of grain (and use these as parents)
Breed the selected plants with each other (cross-breed / allow them to reproduce)
Select offspring with the highest grain yield and breed them again / repeat the process over many generations
Eventually a variety of wheat with a consistently higher yield of grain is produced / desirable phenotype is established in the population

Key terms in this question

selective breeding