Defence Against Disease · Paper 2 — Free Biology SL Practice Questions

The graph below shows antibody concentration in the blood of a patient following two doses of a vaccine. The first dose was given on day $0$, and the second dose (booster) was given on day $28$.

A student investigates the effect of temperature on the activity of lysozyme, an enzyme found in tears and saliva. The student measures the rate of bacterial cell wall breakdown at different temperatures. The results are shown in the table below. Temperature ($^\circ\text{C}$) — Rate (arbitrary units) $10$ — $2$ $20$ — $5$ $37$ — $9$ $45$ — $12$ $55$ — $1$

In a clinical trial for a novel mRNA-based vaccine against a newly emerged viral pathogen, researchers measured the concentration of neutralising antibodies (IgG) in the blood of 50 volunteers over a 12-month period. The vaccine was administered in two doses: the first dose at day 0 and a booster dose at day 28. The mean antibody titres (in arbitrary units, AU) are shown below: Day — Mean antibody titre (AU) | 0 | 14 — 120 28 — 480 42 — 3200 90 — 2800 180 — 1500 360 — 600 A separate group of 50 volunteers who had previously recovered from natural infection with the same virus showed a mean antibody titre of $900\,\text{AU}$ at day 360 post-infection.