MYP Biology sample question: Selective breeding and genetic modification

A farmer wants to develop a herd of cows that produce more milk.

1. (a)Describe how selective breeding could be used to produce cows that give more milk.[3]
   Show the mark scheme for (a)

   • • Choose the cows (and bulls) that produce the most milk (1)
   • • Breed them together (1)
   • • Select the best offspring and repeat over many generations (1)
2. (b)State one difference between selective breeding and genetic modification.[1]
   Show the mark scheme for (b)

   • • Genetic modification transfers a gene directly (possibly from another species) into the genome, taking one generation, whereas selective breeding takes many generations (1)
3. (c)Suggest one ethical concern about genetically modified crops.[1]
   Show the mark scheme for (c)

   • • Any one: possible effects on wild species or biodiversity; unknown long-term health effects; control of seed supply by a few companies (1)

Selective breeding uses natural variation and takes many generations. Genetic modification changes genes directly.