This document discusses different types of genetic variations: - Discontinuous variations are caused by a single gene and result in distinct traits like rolled vs non-rolled tongue. These can be illustrated with a graph showing two clear categories. - Continuous variations are influenced by multiple genes and the environment, like eye/hair color or height. These are shown on a graph as a continuous spectrum rather than two clear groups. Environmental factors can influence continuous traits.

1. Variations Starter activity Explain the following terms Alleles, locus, chromosomes, hetrozygous chromosomes, homozygous chromosomes, genes, and species

2. Variations Learning objectives To determine between ‘continuous’ and ‘discontinuous’ variations To understand that a ‘single’ gene inheritance leads to ‘discontinuous’ variations To appreciate that ‘polygenic’ inheritance leads to ‘continuous’ variations

3. Variations List the ‘similarities’ and ‘differences’ between the human species List those differences in to 2 categories ‘continuous’ variation and ‘discontinuous’ variation List inherited features which can be affected by the environment

4. Discontinuous variation Discontinuous variations relates to a feature which is clear cut (either you have it or not) e.g. rolling of tongue, ear lobe shape, thumb hyperextension. Theses are determined by the alleles of a single gene, no measurements are needed to distinguish between them. Sketch a graph to show the results for the following variations……………………….

5. Discontinuous variations 5 15 Non-tongue roll Tongue roll 10 10 Non-ear lobe Ear lobe 7 13 Non-bend thumb Bend thumb

6. Continuous variations Continuous variations relates to features which are determined by polygenes (many genes) e.g. eye colour, hair colour, skin colour, height, and shape of head. These are variations are greatly influenced by the environment Explain which of the above features and their environmental factors which could influence them

7. Continuous variations Sketch a graph from the following results 5 Hazel 3 Grey 4 Blue 7 Brown 3 Green No. of people Eye colour 3 Ginger 4 Red 1 blonde 2 Brown 10 Black No. of people Hair colour