Scientists investigated the immune responses of healthy mice and mice with contact hypersensitivity (sensitised to the chemical DNCB).
The chemical DNCB causes an immune response in sensitised mice that can make their skin swell. Mice had a solvent vehicle (olive oil) applied to their left ear and DNCB in olive oil applied to their right ear.
The immune response was recorded in two ways:
Table 1 shows the results of this investigation. The values in the brackets show ±2\pm 2±2 standard deviations. A value of ±2\pm 2±2 standard deviations from the mean includes over 95% of the data.
Table 1
| Type of mice | Sex of mice | Mean increase in ear thickness / μm\mu\text{m}μm | Mean concentration of anti-DNCB antibody / arbitrary units |
|---|---|---|---|
| Healthy | Male | 16.2 (±3.8)16.2\ (\pm 3.8)16.2 (±3.8) | 15 (±2)15\ (\pm 2)15 (±2) |
| Healthy | Female | 16.8 (±2.2)16.8\ (\pm 2.2)16.8 (±2.2) | 12 (±3)12\ (\pm 3)12 (±3) |
| Contact-sensitised | Male | 24.2 (±4.5)24.2\ (\pm 4.5)24.2 (±4.5) | 13 (±2)13\ (\pm 2)13 (±2) |
| Contact-sensitised | Female | 15.2 (±2.5)15.2\ (\pm 2.5)15.2 (±2.5) | 25 (±6)25\ (\pm 6)25 (±6) |
Suggest and explain one reason why the olive oil vehicle on its own was applied to the left ear of the mice.
What can you conclude about the effects of contact sensitisation on the cellular response and the humoral response in male and female mice? Use the data in Table 1 to justify your conclusions.
14 exam-style questions on AQA A Level Biology Cell recognition and the immune system, covering Cell recognition and the immune system. Each one has a worked solution and a mark scheme showing where the marks go.