A disease is associated with both a DNA variant and smoking.
Table: Percentage of people who develop the disease
| Group | Non-smokers | Smokers |
|---|---|---|
| Variant absent | 4 | 12 |
| Variant present | 10 | 30 |
Which comparison provides evidence for a genetic influence while keeping smoking status the same?
Variant-absent non-smokers compared with variant-present smokers.
Variant-absent non-smokers compared with variant-absent smokers.
Variant-absent non-smokers compared with variant-present non-smokers.
Variant-present non-smokers compared with variant-present smokers.
40 exam-style questions on Edexcel GCSE Biology 3.4 Variation and the Human Genome Project, covering 3.4.1 Causes of variation, 3.4.2 Outcomes of the Human Genome Project, 3.4.3 Genetic variation within a population, and 3.4.4 Effects of genetic mutations on phenotype. Each one has a worked solution and a mark scheme showing where the marks go.