Who is known as the father of passive immunity?

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?

The skin and mucous membrane act as which type of barrier in innate immunity?

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

Why is an antibody molecule represented as $H_2L_2$?

In which lymphoid organ are all blood cells,including lymphocytes,produced?