A species of bacterium occurs in two forms. Form 2 has a changed surface antigen.
Scientists added equal concentrations of three antibodies to the same number of bacteria from each form. They recorded the percentage of bacteria with antibody attached after the same length of time.
| Antibody | Bacteria with antibody attached in form 1 (%) | Bacteria with antibody attached in form 2 (%) |
|---|---|---|
| P | 9 | 8 |
| Q | 94 | 16 |
| R | 11 | 10 |
Describe the effect of the changed antigen on the binding of the three antibodies.
Explain the difference between the results for antibody Q and the possible effect on bacterial destruction.
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.