Answer: Plasma cells (activated B cells).
- A T cells, which instead directly attack infected cells
- B Macrophages, which primarily engulf and digest pathogens
- C Plasma cells (activated B cells)
- D Natural killer cells, which target virus-infected cells
Correct answer: C. Plasma cells (activated B cells)
Explanation: Plasma cells are differentiated B lymphocytes that secrete large amounts of antibodies. When a B cell is activated by an antigen (with T helper cell help), it divides and differentiates into plasma cells and memory B cells.
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.