A explanation of how mutations arise and what their effects might be. There are four main causes – radiation, UV light, X-rays and some chemicals. We also see how cystic fibrosis and Down's syndrome are inherited.

First broadcast:
21 November 2008

Discuss with students the role of mutation in the production of variation in populations and in the process of evolution. While mutations can be harmful, it is important for students to understand that they can also be advantageous or neutral. Go over the example of cystic fibrosis shown and ask students to produce a presentation that explains how the condition is inherited.