Scientists recorded the average number of units of alcohol consumed each day and the incidence of liver disease over 10 years in groups of adults. The results are shown in the table.
| Average units of alcohol consumed each day | New cases of liver disease per 1000 adults over 10 years |
|---|---|
| 0 | 8 |
| 5 | 19 |
| 10 | 34 |
A separate investigation found that substances made when the liver breaks down alcohol damage liver cells.
Which conclusion is valid?
The table alone shows that alcohol causes liver disease, so the damage to liver cells adds no further evidence
Alcohol intake is correlated with liver disease, but there is no causal mechanism because not every drinker developed it
Alcohol is not a cause of liver disease, because some adults who drank no alcohol still developed liver disease
Alcohol intake is correlated with liver disease, and the damage to liver cells provides a causal mechanism for this link
304 exam-style questions on AQA GCSE Biology 2.2 Animal tissues, organs and organ systems, covering 2.2.1 The human digestive system, 2.2.2 The heart and blood vessels, 2.2.3 Blood, 2.2.4 Coronary heart disease: a non-communicable disease, 2.2.5 Health issues, 2.2.6 The effect of lifestyle on some non-communicable diseases, and 2.2.7 Cancer. Each one has a worked solution and a mark scheme showing where the marks go.