Which of the following are phagocytic in nature?

The grafting principle depends upon the

The toxic substances produced by foreign bodies that trigger an immune response are known as:

Assertion $A$: Innate immunity consists of various barriers. Reason $R$: Exposure to a pathogen is required for the stimulation of innate immunity. Which option is correct for Assertion $A$ and Reason $R$?

Which lymphoid organ shows a reduction in size with increasing age?

Which of the following statements are correct regarding the structure and types of antibodies in humans?
$i$. Antibodies are also called Immunoglobulins that are produced as an immune response to antigenic stimulation.
$ii$. They are produced by all types of $T$-lymphocytes and $B$-lymphocytes.
$iii$. An antibody is a $Y$-shaped molecule formed of four polypeptide chains. Antibodies present in plasma determine many blood group systems like $ABO$,$Rh$,$P$,$MNS$ etc.
$iv$. An antibody molecule consists of two antigen-binding sites called paratopes.