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

Which of the following are types of immunity?

Viruses infect host cells. By the induction of viruses,the host cells produce which of the following?

Interferons curb the infection of:

Along with lymphoid organs,$WBCs$ are also present within the mucosa of digestive,respiratory,and excretory tracts as $MALT$,which constitutes about $.......$ of the total lymphoid tissue of the body: (in $\%$)

Which group of cells acts as phagocytes?