Consider the following statements

$I.$ People should get vaccination to avoid infection

$II.$ Vaccination is available against polio, cholera, typhoid, tuberculosis and many othe disease

$III.$ Eradication of vectors are necessary in diseases like malaria and filariasis

$IV. $ Dengue and chikengunya, both are spread by Culex mosquitoes

Which of the statements given above are correct?

Humans have acquired immune system that produces antibodies to neutralize pathogens. Still innate immune system is present at the time of birth because it

When an organ is transplanted and is rejected by the body, the lymphocytes are produced by

Where are $B\,-$ cells and $T\,-$ cells formed ? How do they differ from each other ?

Each antibody has $…A…$ polypeptide chains, $…B…$ small chains called $….C…$ chains and $…D…$ longer chains called $.E…$ chains

The antibody, therefore, is represented as $…F…$

Here $A$ to $F$ refers to