Question

Read the following passage and answer the questions that follow :

Immunity in our body is of two types (i) Innate immunity, and (ii) Acquired immunity. Innate immunity is a non-specific defence mechanism, whereas Acquired immunity is pathogen specific. Acquired immunity is characterised by memory. Antibodies are specific to antigens and there are four types of antibodies produced in our body - IgA, IgE, IgG and IgM. It shows primary response where it encounters the pathogen for the first time and secondary response during the subsequent encounters with the same antigen/pathogen. These immune responses are carried out with the help of two special types of lymphocytes present in the blood.

Name the two types of specialised cells which carry out the primary and secondary responses.

Hint:

Two types of lymphocytes in blood act against a specific antigen and keep memory of it.

Answer 1

Step 1: Understand what the passage says:
The passage says that acquired immunity gives a primary response and a secondary response.
It also says that two special types of lymphocytes in the blood carry out these responses.

Step 2: Recall the lymphocytes of the acquired immune system:
The blood has two kinds of lymphocytes that act on a specific antigen: B-lymphocytes and T-lymphocytes.
B-lymphocytes make the antibodies (humoral response) and T-lymphocytes help B-cells and carry out the cell-mediated response.
Both kinds leave behind memory cells, which give a quicker and stronger secondary response.

Final Answer:
The two specialised cells are B-lymphocytes (B-cells) and T-lymphocytes (T-cells).