The function of a vaccine is the production and storage of

How many peptide chains are present in the structure of an antibody?

Antibodies . . . . . . are abundant in colostrum.

Given below are two statements.
Statement $I$: Passive immunity is acquired when readymade antibodies are received by body cells.
Statement $II$: Resistance induced by $BCG$ vaccine is an example of passive immunity.
In the light of the above two statements,choose the correct answer from the options given below.

When pre-formed antibodies are injected into the body,it is called .........

Acid in the stomach,saliva in the mouth,and tears from the eyes all prevent microbial growth. These belong to which of the following barriers?