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10.1 Antibody-Based Diagnostics — Test 1
Q1. Serology is the branch of immunodiagnostics that:✓ Detects antigens or antibodies in serum using antigen–antibody reactions
Q2. The high specificity of antibody-based diagnostic tests comes from:✓ The precise binding of antibody to its specific epitope
Q3. A precipitation reaction in diagnostics requires:✓ A soluble antigen and antibody forming a cross-linked lattice
Q4. Agglutination tests (e.g. blood typing) detect:✓ Antibody-mediated clumping of particulate antigens
Q5. ELISA (enzyme-linked immunosorbent assay) detects antigen or antibody using:✓ An enzyme-labelled antibody that produces a colour change with substrate
Q6. In a sandwich ELISA for an antigen, the antigen is captured between:✓ A surface-bound capture antibody and a labelled detection antibody
Q7. Radioimmunoassay (RIA) differs from ELISA in that it uses:✓ A radioactive label instead of an enzyme
Q8. Immunofluorescence uses antibodies labelled with:✓ Fluorescent dyes (fluorochromes)
Q9. A Western blot identifies a specific protein by:✓ Separating proteins by size, then detecting with a specific antibody
Q10. The direct Coombs (antiglobulin) test detects:✓ Antibody or complement already bound to a patient's red cells
Q11. A lateral-flow immunoassay (e.g. a home pregnancy or rapid antigen test) works by:✓ Capillary flow of sample over immobilised antibodies giving a visible line
Q12. Sensitivity of a diagnostic test refers to its ability to:✓ Correctly identify those who have the condition (few false negatives)
Q13. Specificity of a diagnostic test refers to its ability to:✓ Correctly identify those without the condition (few false positives)
Q14. Why are monoclonal antibodies often preferred in diagnostic assays?✓ They are uniform and recognise a single defined epitope, improving consistency/specificity
Q15. Detecting specific IgM rather than IgG in a serological test suggests:✓ Recent or acute infection
Q16. An indirect ELISA to detect antibody in a patient's serum uses:✓ Plate-bound antigen, the patient's antibody, then a labelled anti-immunoglobulin
Q17. The prozone phenomenon can cause a false-negative result in agglutination/precipitation tests when:✓ Antibody is in great excess, preventing lattice formation
Q18. Flow cytometry uses fluorochrome-labelled antibodies to:✓ Identify and count cells by their surface (and intracellular) markers
Q19. A confirmatory test is generally chosen to be:✓ Highly specific, to rule in disease after a sensitive screen
Q20. Match each technique with what it primarily relies on and select the correct option.✓ A-ii, B-i, C-iv, D-iii