Two regions have the same age distribution. The table shows results from a survey.
Table
| Region | Percentage of adults who smoke | Lung cancer cases per 100000 adults |
|---|---|---|
| P | 15 | 45 |
| Q | 30 | 90 |
A student concludes that smoking is the only cause of lung cancer and that halving smoking immediately halves cancer cases.
Which statement identifies two limitations of this conclusion?
Other risk factors were not measured, and cancers may develop after long delays.
Cancer cases cannot be compared as rates, and cancers may develop after long delays.
Other risk factors were not measured, and matching age removes all smoking effects.
Matching age removes all smoking effects, and cancer cases cannot be compared as rates.
44 exam-style questions on Edexcel GCSE Biology 5.4 Non-communicable diseases, covering 5.4.1 Interaction of factors in non-communicable disease, 5.4.2 Lifestyle factors and non-communicable disease, and 5.4.3 Treatments for cardiovascular disease. Each one has a worked solution and a mark scheme showing where the marks go.