Question

Read the following statements (1 - 2) and select the correct option.

Statement 1 : Mature and naive B-lymphocytes are synonymous and can be used interchangeably to represent the same cell.
Statement 2 : A single plasma cell can secrete more than 2000 antibody molecules per second.

• A. Both the statements 1 and 2 are correct
• B. Statement 1 is correct and statement 2 is incorrect
• C. Statement 2 is correct and statement 1 is incorrect
• D. Both the statements 1 and 2 are incorrect

Answer 1

The correct option is C Statement 2 is correct and statement 1 is incorrect

B-cells are a type of lymphocytes mature in the bursa of Fabricius (in birds) or bone marrow (in mammals).

B-cell is said to be naive until it is exposed to the antigen. Thus both the terms may represent the same cell but they can not be used interchangeably. So statement 1 is incorrect.

A B-cell is called a mature cell once it is fully developed and leaves the bone marrow. Once a B-cell encounters an antigen that binds to its membrane-bound antibody, it causes the cell to divide rapidly and differentiates into plasma cells and memory cells.

The plasma cells are short-lived and responsible for the secretion of soluble antibodies. A single plasma cell can secrete more than 2000 antibody molecules per second. Hence statement 2 is correct.

Memory cells help in secondary immune response (immune response during subsequent encounters with the same antigen).

Figure : Formation of plasma cells and memory cells