| Date | May 2013 | Marks available | 1 | Reference code | 13M.1.HL.TZ2.38 |
| Level | Higher level | Paper | Paper 1 | Time zone | Time zone 2 |
| Command term | Question number | 38 | Adapted from | N/A |
Question
Which of the following events form the basis of immunity upon which the principle of vaccination is based?
Markscheme
D
Examiners report
Eight teachers objected to this question. Student performance on the question was poor with only 30% answering it correctly. The choice of incorrect response was spread between responses A, B and C. Students should have been easily able to rule out A and B as clonal selection is a clear part of the outcome. If students understand the clonal selection process correctly, then they would know that injection with an attenuated virus would result in polyclonal antibodies.
