EXTENSION TOPICS, Topic A - Infectious Diseases
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Q: What does EXTENSION TOPICS, Topic A - Infectious Diseases cover?
A: Integrate immunology, pathogen biology, epidemiology, and public health strategy so the 2026 H2 Biology infectious diseases extension questions become an opportunity to score.
Status: SEAB H2 Biology (9477, first exam 2026) syllabus last checked 2026-01-12. Extension Topic A scope (immunity, pathogens, antibiotics, epidemiology) and Paper 3/4 assessment hooks remain unchanged. [1]
Why this extension matters
- Real-world relevance: Pandemic literacy and antimicrobial resistance are assessed through data handling, case studies, and ethical evaluation.
- Integration: Requires command of cell biology (immune cells), genetics (somatic recombination), and population biology (epidemiology).
- Assessment trend: Paper 3 essays and Paper 4 data questions frequently use infectious disease narratives to test synthesis.
Syllabus map
- Innate vs adaptive immunity, active vs passive immunity
- Roles of B cells, T cells, antigen-presenting cells, memory cells
- Antibody structure (IgG) and diversity generation (somatic recombination, hyper-mutation, class switching) [1]
- Vaccination principles, herd immunity, risks
- Viral pathogenesis (influenza, HIV) and bacterial infection (Mycobacterium tuberculosis)
- Modes of action of antibiotics (penicillin focus) and resistance issues
- Epidemiological metrics: , outbreak/epidemic/pandemic definitions
Concept 1: Immune system overview
Innate immunity: First-line defences (skin, mucous, microbiota), cellular components (phagocytes, NK cells), inflammatory mediators (histamine, cytokines). Emphasise pattern recognition receptors (PRRs) such as toll-like receptors (TLRs) detecting pathogen-associated molecular patterns (PAMPs). [2]
