The grafting between two identical twins is known as

$MALT$ constitutes about what percentage of the lymphoid tissue in the human body (in $, \%$)?

Transplantation of tissues/organs often fails due to non-acceptance by the patient's body. Which type of immune response is responsible for such rejections?

Vaccination provides protection to an individual against a disease because it.........

In active acquired immunity,.........

Assertion : Organ transplantation patients are given immunosuppressive drugs.
Reason : Transplanted tissue has antigens which stimulate the specific immune response of the recipient.