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4.2 Humoral Immunity β Test 1
Q1. Humoral immunity is mediated primarily by:β Antibodies produced by B cells/plasma cells
Q2. Neutralisation by antibodies refers to:β Blocking a toxin or virus from binding host cells
Q3. Opsonisation by antibody enhances:β Phagocytosis of the antibody-coated target
Q4. Antibody-dependent cell-mediated cytotoxicity (ADCC) involves:β NK cells killing antibody-coated target cells via Fc receptors
Q5. Complement fixation by antibody leads to:β Opsonisation, inflammation and membrane attack complex formation
Q6. The effector cell that actually secretes antibody is the:β Plasma cell
Q7. T-dependent B-cell activation requires a second signal from helper T cells via:β CD40LβCD40 interaction and cytokines
Q8. The primary humoral response is dominated by which antibody class?β IgM
Q9. Affinity maturation of antibodies occurs through:β Somatic hypermutation and selection in germinal centres
Q10. Secretory IgA protects mucosal surfaces mainly by:β Immune exclusion β blocking pathogen attachment
Q11. Class (isotype) switching changes the antibody's:β Heavy-chain constant region (function) while keeping specificity
Q12. T-independent antigens (e.g. polysaccharides) typically elicit:β Mainly IgM with little memory
Q13. Maternal antibody in breast milk provides the infant with:β Secretory IgA that protects the gut mucosa
Q14. The Fc region of an antibody is important for humoral effector functions because it:β Binds complement and Fc receptors on immune cells
Q15. A key advantage of the secondary humoral response over the primary is:β Higher-affinity, predominantly IgG antibody produced more rapidly
Q16. Agglutination of particulate antigens by antibody is most efficiently mediated by:β IgM, due to its high valence
Q17. Hyper-IgM syndrome, with failure of class switching, is typically caused by a defect in:β CD40L (CD154) signalling
Q18. The principal protective mechanism of antibodies against extracellular bacterial toxins is:β Neutralisation
Q19. Most antibody class switching and affinity maturation take place in the:β Germinal centres of secondary lymphoid organs
Q20. Place these events of an adaptive humoral response in order: (i) epitope binds lymphocyte receptors; (ii) plasma and memory cells form; (iii) antibodies activate effector mechanisms; (iv) pathogen is destroyed.β i β ii β iii β iv
Q21. Match each antibody effector mechanism with its description and select the correct option.β A-iii, B-i, C-iv, D-ii