Explain why a person who has received a blood transfusion containing antibodies against a particular pathogen will only be protected from that pathogen for a short period of time.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Doctors can treat some infections by giving patients a transfusion of blood plasma containing ready-made antibodies against a specific pathogen. This is called passive immunity.
Model answer (4 marks)
The antibodies are supplied directly from the donor and are not produced by the patient’s own white blood cells or lymphocytes. Because they are not produced by the patient’s immune system, no memory B‑cells are created and the immune system has not been stimulated to generate a secondary response. The transfused antibodies are gradually broken down and destroyed over time. Consequently, when the pathogen is encountered again the patient’s immune system cannot produce antibodies quickly enough, so protection is short‑lived.
Examiner tips
- Use the exact phrase ‘not produced by the patient’s own white blood cells or lymphocytes’
- Explain that no memory cells are formed
- Mention antibody breakdown over time
- State that a rapid secondary response cannot occur
Common mistakes
- Confusing passive immunity with active immunity and saying memory cells are formed
- Failing to mention antibody breakdown
- Using vague terms like ‘short period’ without explaining why
Mark scheme (4 marks)
- The antibodies are not produced by the patient's own white blood cells / lymphocytes
- No memory cells are produced / the immune system has not been stimulated to produce memory cells
- The antibodies are broken down / destroyed over time
- So when the pathogen is encountered again, the immune system cannot produce antibodies quickly enough / there is no rapid secondary response
Key terms in this question
Related
- All Eduqas GCSE Biology revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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