Answer: Each B cell has receptors for one specific antigen; when that antigen binds, the B cell is selected and clonally expands to produce many identical plasma cells secreting specific antibody.
- A Antibodies are sometimes mistakenly thought to be produced through a largely random, unregulated process unrelated to the actual antigen encountered as generally observed in typical laboratory settings
- B Each B cell has receptors for one specific antigen; when that antigen binds, the B cell is selected and clonally expands to produce many identical plasma cells secreting specific antibody
- C T cells are sometimes mistakenly thought to randomly select which B cells become activated antibody-secreting plasma cells in the lymph node under usual circumstances according to most researchers
- D The immune system is sometimes mistakenly thought to actively choose in advance which future pathogens it will need to defend against in the majority of cases studied as widely reported
Correct answer: B. Each B cell has receptors for one specific antigen; when that antigen binds, the B cell is selected and clonally expands to produce many identical plasma cells secreting specific antibody
Explanation: Clonal selection (Burnet, 1957): millions of B cells exist, each with receptors for ONE specific antigen. When the matching antigen binds, that B cell is selected, proliferates (clonal expansion), and differentiates into plasma cells and memory cells. This explains specificity of immune response.
An antibody is Y-shaped, with two identical antigen-binding sites at the tips of the variable regions - each shaped to recognise one specific antigen - while the constant (Fc) region at the base is recognised by immune cells to trigger further responses.
Concept context
Innate and adaptive immunity, B cells, T cells, antibodies, vaccines, and immune disorders. Critical for NEET.