Question

ASSERTION
B-lymphocytes produce an army of proteins against invading pathogens that are called antibodies.
REASON
The T-cells themselves do not secrete these antibodies but help B-cell to produce them.
A) Statement B is correct and A is incorrect.
B) Both the statements are incorrect.
C) Statement A is correct and B is incorrect.
D) Both the statements are correct.

Answer 1

Hint: B-cells and T-cells are the cells of an adaptive immune response. They are released when a person encounters an antigen or any foreign invader. The B-cells attack the pathogens by secreting antibodies when T-cells have presented the antigens or pathogens to the B-cells.

Complete answer:
Option (A): Statement B is correct and A is also correct. The role of B-lymphocytes is to produce an army of proteins called antibodies that are active against antigens or invading pathogens.
Option (B): Both the statements are not incorrect because the B-lymphocytes produce humoral immunity (releasing antibodies) while the T-lymphocytes produce cell-mediated immunity and they help the B-lymphocytes to produce the antibodies.
Option (C): Statement A is correct and also B is correct. The production of antibodies by B-lymphocytes is aided by the action of T-lymphocytes.
Option (D): Whenever a person encounters an antigen then that person’s immune system starts producing specific antibodies against that antigen. This whole process is mediated by the T-cells and B-cells of the immune system. Upon encountering the antigen, the T-cells present these antigens to the plasma cells which secrete B-cells. These B-cells start producing antibodies against that specific antigen. Thus, we can conclude that the B-cells produce an army of proteins called antibodies against invading pathogens and the T-cells help the B-cells to produce antibodies. So, both the statements are correct.

Hence, the correct option is (D).

Note: The function of T-cells and B-cells is to recognize specific ‘non-self’ antigen which is also known as antigen presentation. Once, the antigen has been identified, B-cells produce antibodies while the T-cells such as T-helper cells produce cytokines that will aid the B-cells to produce antibodies, and cytotoxic T-cells that produce toxic granules will induce the death of pathogen-infected cells.