Exam Tips: Selective Breeding

Always include "over many generations": This phrase appears in virtually every AQA mark scheme for selective breeding process questions. Without it, you will likely lose a mark.

Link the disadvantage to the mechanism: Saying "it reduces genetic variation" alone is often not enough. Explain why this is a problem: "If all individuals have similar alleles, a disease that one individual cannot resist will affect the entire population."

Selective breeding does not create new genes: A common error is saying breeders "give" organisms new genes. Breeders only select from variation that already exists. This is the key difference from genetic engineering.

Be specific with examples: Generic answers score less than specific ones. "Cows selected for milk yield" scores better than "animals selected for good traits."