State the three characteristics of acquired immunity.

Explanation

The characteristics of acquired immunity are
(i) It is pathogen specific.
(ii) It is characterised by memory.
(iii) Responses can be characterised as a primary response (of low intensity) and secondary response.
Acquired immunity can be attained by humans in the following ways:
(i) Active immunity The antibodies are produced in the host body as a response to foreign entities, i.e. living microbes or other proteins. Its onset of response is slow.
(ii) Passive immunity The readymade antibodies are directly introduced to protect the body against foreign agents.