Defence Against Disease · Paper 1 — Free Biology HL Practice Questions

A patient with a weakened immune system receives a vaccine containing inactivated influenza virus. Two weeks later, a blood test shows an elevated concentration of antibodies specific to influenza haemagglutinin. What is the most direct role of the inactivated virus in stimulating this response?

A child receives a combined vaccine containing attenuated measles virus and inactivated polio virus. Years later, the child is exposed to wild-type measles virus but remains healthy. Which statement best explains this protection?

Both a live attenuated vaccine and an inactivated virus vaccine are tested in separate groups. After the full vaccination course, both groups show similar levels of neutralizing antibodies. Months later, when exposed to the wild-type virus, the live attenuated group shows significantly stronger protection. Which of the following most likely explains this difference?