The clinging of $RBCs$ together in the blood and forming a pile of coin-like structure is known as

Antibodies are produced by

The universal donor is

Mature human $RBCs$ are enucleated. Which of the following is the most appropriate explanation for this?
$(i)$ They do not need to reproduce.
$(ii)$ They are somatic cells.
$(iii)$ They do not perform metabolism.
$(iv)$ Their internal space is available for $O_2$ transport.

Hemoconia are -

The role of the spleen in mammals is . . . . . . .