Genetic variation and its control is one of the subjects looked at in GCSE Science. This is the last of four quizzes on the subject and it looks specifically at genetic engineering.
Humans have sought to control genes and to exploit genetic variation for thousands of years. Selective breeding has been used to modify the characteristics of plants and animals to better suit our needs. Examples are disease resistant plants, or cattle that give high yields of milk. But there are problems with this, since future generations of selectively bred organisms will share increasingly similar genes.
During the twentieth century, scientists began to understand genes and genetics more deeply than before. Knowledge has reached the point where it is now possible to identify a gene for a particular characteristic and transfer it artificially into an organism. This is called genetic engineering and it allows genes to be transferred from the same species or from different species.