A flock of sheep is given a vaccine containing dead pathogen R. Several months later, the sheep encounter live pathogen R.
Why are the vaccinated sheep less likely to develop serious symptoms?
Memory lymphocytes recognise R's antigens and rapidly produce many antibody-secreting cells.
Memory lymphocytes destroy pathogen R without producing any antibodies.
Dead pathogen R remains in the sheep and directly kills the live pathogen.
Antibodies in the vaccine reproduce rapidly when live pathogen R enters the sheep.
87 exam-style questions on Edexcel GCSE Biology 5.3 Immune system and medicines, covering 5.3.1 The specific immune system, 5.3.2 Response to immunisation, 5.3.3 Advantages and disadvantages of immunisation, 5.3.4 Antibiotics and bacterial infections, 5.3.5 Aseptic techniques in culturing, 5.3.6 Cross-sectional areas of cultures, 5.3.7 Stages of developing new medicines, and 5.3.8 Production of monoclonal antibodies. Each one has a worked solution and a mark scheme showing where the marks go.