Assuming no one with AD died in 2014, calculate the annual percentage increase in AD cases in America for 2014 (lines 2–4).

Explain how donepezil could improve communication between nerve cells (lines 7–9).

Suggest and explain two reasons why there is a high frequency of the E280A mutation in Yaramul (lines 13–15).

1

2

Explain why natural selection has not reduced the frequency of the E280A mutation in the population (lines 16–17).

The age at which the E280A mutation is expressed to cause AD can vary (lines 11–12).

Suggest and explain one reason for this.

One scientific study which analysed chromosome 14 involved 102 individuals. The scientists recorded a sample size of 204. In this sample they detected 75 E280A mutations but only 74 potential AD cases (lines 19–21).

Suggest explanations for the figures the scientists recorded.

Suggest why a DNA probe for the mutated triplet was not considered a suitable method for detection of the E280A mutation (lines 22–23).