The grafting between two identical twins is known as

Lymphocytes are sensitive to .........

The mucus coating of the lining of the urogenital tract helps in trapping microorganisms entering our body. Which type of barrier is this?

The antigen-binding site in an antibody is found between:

Match the following columns:

Column-$I$	Column-$II$
$(A)$ Primary lymphoid organs	$(i)$ Thymus
$(B)$ $MALT$	$(ii)$ Spleen
$(C)$ Organ located near the heart	$(iii)$ Bone marrow
$(D)$ Bean-shaped organ	$(iv)$ Appendix
	$(v)$ $50\%$ of lymphoid tissue

Select the incorrect statement with respect to acquired immunity.