Topic Summaries

Selective breeding

IGCSE > Biology > CIE > IGCSE Biology Topic Summaries > Genetic engineering and modification > Selective breeding
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  • Selective breeding (artificial selection) is the process by which humans breed plants and animals for particular genetic characteristics.
  • Humans have been doing this for thousands of years, e.g. the breeding of food crops from wild plants and the domestication of animals.
  • Selective breeding involves:
    • Choosing parents with a desired characteristic from a mixed population and breeding them together.
    • Choosing the offspring with the desired characteristic and breeding them together.
    • Repeating the cycle over many generations until all offspring show the desired characteristic.
  • The characteristic can be chosen for its usefulness or appearance:
    • Animals that produce more meat or milk.
    • Disease resistance or increased size in food crops.
    • Domestic dogs with a gentle nature.
    • Large or unusual flowers.
  • Disadvantages of selective breeding:
    • Can lead to ‘inbreeding’ when the parents are genetically very similar, where some breeds are especially prone to inherited defects or disease.
    • Reduced genetic variation means that a change in the environment or a disease is more likely to kill an entire population.
    • Physical problems in organisms, e.g. cows weighed down by large udders.
    • The breeding method (e.g. artificial insemination) can be seen as unethical.

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