Question

Define Antigen.
Topic: Human health and diseases

Answer 1

Antigens are substances that stimulate the immune system to produce antibodies. Each antigen has a distinct surface feature or epitope. Thus there is a resultant effect of a specific response.  Antigens could be anything like a pathogen or bacteria or fungi or even virus. They cause diseases or allergic reactions.
Antigens are generally proteins. But they can be lipids, carbohydrates or nucleic acids. Antigens can be of three types – Exogenous, endogenous and autoantigens. Antigens can also be foreign bodies that stimulate the immune system of the body. Even pollen and spores can be antigens.


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Answer 2

Answer:

The substances organisms that have the capability to stimulate the immune system of an organism and provoke the immune system to release antibodies is called as an antigen.

Explanation:

Antigens contain specific sides called epitopes which are responsible for the stimulation of the immune system.

Antigens may be living or nonliving.

This may cause allergy or diseases.

Bacteria or fungi or virus are are considered as living antigens where as dust and pollutants are considered as non living antigens.