Assessment criteria 1.3
Q3. (a) Explain the meaning of each of the following terms:
(i) Variation
(ii) Mutation
a. Explain how mutation causes variation. Give examples.
b. Explain how meiosis causes genetic variation in the gametes.
Assessment criterion 1.4
The classical twin study is established as the definitive study design for investigating the relative importance of genetic and environmental factors to traits and diseases in human population.
Monozygotic (identical) twins share all of their genes, while Dizygotic(fraternal) twins share only about 50 percent of them, the same as non-twin siblings. If a researcher compares the similarity between sets of identical twins to that of fraternal twins for a particular trait, then any excess likeness between the identical twins should be due to genes rather than environment.
