Infection & ResponseTopic Summary
Knowledge Organiser
Part of Adaptive Immunity and Antibodies — GCSE Biology
This topic summary covers Knowledge Organiser within Adaptive Immunity and Antibodies for GCSE Biology. Specific immune responses, antibody production, lymphocytes, memory cells It is section 15 of 15 in this topic. Use this topic summary to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 15 of 15
Practice
20 questions
Recall
25 flashcards
Knowledge Organiser
Key Cells
- B lymphocyte — recognises antigen, divides, forms plasma cells and memory B cells
- Plasma cell — secretes thousands of antibodies per second specific to one antigen
- Memory B cell — long-lived, enables fast secondary response
- Helper T cell — coordinates immune response, activates B cells
- Killer T cell — directly destroys infected body cells
Key Processes
- Clonal selection — antigen selects specific B cell with matching receptor shape
- Clonal expansion — selected B cell divides repeatedly
- Antibody production — plasma cells secrete specific antibodies
- Primary response — slow (5–10 days), low antibody levels, creates memory cells
- Secondary response — fast (1–3 days), high antibody levels, prevents disease
Common Marks Lost
- Saying antibodies kill pathogens (they tag them for phagocytes)
- Confusing plasma cells (make antibodies now) with memory cells (future protection)
- Saying secondary response is slower (it is much faster)
- Not explaining WHY secondary response is faster (memory cells already present)
- Using antibiotics for viral infections
Key Terms
- Antigen — foreign molecule that triggers immune response
- Antibody — specific Y-shaped protein that tags pathogens
- Antitoxin — antibody that neutralises a toxin
- Phagocytosis — engulfing and destroying pathogens
- Immunological memory — ability to respond faster on second exposure