Selective breeding of plants and animalsSpec 5.10, 5.11
In short
Selective breeding is when humans choose parents with a desired characteristic, such as high milk yield or disease resistance, and breed them together. Offspring showing the characteristic are bred again, repeated over many generations. It gives higher yields, but breeding from a few individuals reduces genetic variation and inbreeding can make harmful inherited conditions more common.
Selective breeding is when humans choose which organisms to breed so that the desired characteristics are passed on to the next generation. It has been used for thousands of years to develop plants and animals with useful features.
- Decide which characteristic is wanted, for example high milk yield or disease resistance.
- Choose parents that show the characteristic most strongly and breed them together.
- From the offspring, select those with the characteristic and breed them together.
- Repeat over many generations until the desired characteristic is strongly shown.
| Organism type | Characteristics selected for |
|---|---|
| Food plants (crops) | Disease resistance, larger fruit or grains, better taste, higher yield |
| Domesticated animals | More milk, more meat, more eggs, a gentle nature, wool quality |
Impact of selective breeding
- Food plants and animals give higher yields, so more food can be produced from the same land.
- Crops can be bred to resist disease, so less is lost.
- Breeding from only a few individuals reduces genetic variation in the population. If a new disease or a change in the environment appears, all individuals may be affected.
- Closely related individuals are bred together (inbreeding), which can make harmful inherited conditions more common in domesticated animals.
Always say that selection is repeated over many generations. Mark schemes award a mark for this.
Written and checked against the Edexcel IGCSE Science Double Award (4SD0) specification · Updated October 2026