Type 1 and Type 2 diabetes are chronic metabolic disorders characterised by elevated blood glucose levels. Type 1 diabetes is an autoimmune condition resulting in the destruction of insulin-producing beta cells, whereas Type 2 diabetes is primarily characterised by progressive insulin resistance and is highly associated with lifestyle factors.
Researchers investigated the occurrence of these two conditions in twin pairs. Monozygotic (identical) twins share 100%100\%100% of their genetic material, whereas dizygotic (non-identical) twins share approximately 50%50\%50%.
In each twin pair studied, at least one twin had been diagnosed with diabetes. The table below shows the concordance rate (the percentage probability of the second twin developing the condition when the first twin has it):
| Twin type | Type 1 diabetes (%) | Type 2 diabetes (%) |
|---|---|---|
| Identical (monozygotic) | 35 | 75 |
| Non-identical (dizygotic) | 6 | 12 |
Explain what conclusions can be drawn from the data in the table about the relative influence of genetics and the environment on the development of Type 1 and Type 2 diabetes.
32 exam-style questions on OCR A A Level Biology Patterns of inheritance. Each one has a worked solution and a mark scheme showing where the marks go.