HSC Biology — Module 7
Adaptive Immunity — Flashcards & Quiz
Adaptive (specific) immunity is the third line of defence that generates targeted responses against specific pathogens, and HSC Biology Module 7 asks you to distinguish it clearly from innate immunity. Focus on B lymphocytes (antibody production), helper and cytotoxic T lymphocytes, the primary vs secondary response curves, and how memory cells underpin vaccination. Diagrams of antibody structure and clonal selection are high-yield.
Key Points
- Adaptive immunity is specific to each pathogen and has immunological memory — the two features that distinguish it from innate immunity.
- B lymphocytes differentiate into plasma cells that secrete antibodies (humoral immunity); antibodies tag pathogens for destruction via agglutination, neutralisation, or complement.
- T lymphocytes: helper T cells coordinate the response, cytotoxic T cells kill infected host cells directly (cell-mediated immunity).
- Primary response is slow (days) and produces moderate antibody levels; secondary response is fast (hours) and produces much higher antibody levels due to memory cells.
- Clonal selection: a specific B or T cell is activated by an antigen that matches its unique receptor, then proliferates into an army of identical clones.
- Diagram skill: be able to draw an antibody Y-shape and label the antigen-binding sites (Fab) and constant region (Fc).
Common Mistakes to Avoid
- Confusing innate (non-specific, fast) with adaptive (specific, slow but memory).
- Mixing up B cells (antibody production) and T cells (cellular immunity).
- Forgetting memory cells are the basis of immunological memory and vaccine effectiveness.
- Drawing antibodies without showing the Y-shape with two antigen-binding sites.
- Claiming the primary response produces more antibodies than the secondary response — it's the opposite.
Exam Strategy
HSC Module 7 adaptive immunity questions ask you to describe the response or compare primary and secondary. Structure: (1) antigen detected by B/T cells, (2) clonal selection of matching cells, (3) proliferation into plasma cells (antibodies) or active T cells, (4) memory cells persist. For comparison, emphasise speed, magnitude, and duration differences.
Sample Flashcards
Q1: What is the role of B lymphocytes (B cells)?
B cells are part of the adaptive immune system (humoral immunity). When activated by an antigen, B cells differentiate into plasma cells that produce antibodies specific to that antigen. Memory B cells persist for rapid response upon re-exposure.
Q2: What is the role of T lymphocytes (T cells)?
T cells are part of cell-mediated immunity. Helper T cells activate B cells and other T cells. Cytotoxic (killer) T cells directly destroy infected cells. Memory T cells remain for future rapid response. T cells recognise antigens presented on MHC molecules.
Q3: What is the difference between active and passive immunity?
Active immunity: body produces its own antibodies and memory cells. Can be natural (infection) or artificial (vaccination). Long-lasting. Passive immunity: body receives pre-made antibodies from another source. Natural (mother's antibodies via placenta/breast milk) or artificial (injection of antibodies). Short-lived.
Sample Quiz Questions
Q1: B cells produce antibodies as part of the humoral immune response.
Answer: TRUE
B cells differentiate into plasma cells that secrete antibodies specific to antigens. This antibody-mediated response is called humoral immunity.
Q2: Helper T cells directly kill infected cells.
Answer: FALSE
Helper T cells COORDINATE the immune response by activating B cells and cytotoxic T cells. CYTOTOXIC (killer) T cells directly destroy infected cells.
Q3: Passive immunity provides long-lasting protection because it generates memory cells.
Answer: FALSE
Passive immunity provides SHORT-LIVED protection because the body receives pre-made antibodies but does NOT produce its own memory cells. Only active immunity generates memory cells.
Revision Tip
Primary vs secondary response curves are a classic diagram — drill a Revizi flashcard that asks you to sketch both curves with axis labels.
Related Concepts
Last updated: March 2026 · 3 flashcards · 3 quiz questions