Tears and mucous membrane are part of the General defense
system. The General defense system of the body consists of the skin, clotting,
sweat glands, lysozyme, mucous membranes, nasal hairs, cilia, hydrolic acids,
and the vagina. General defense systems have a vital role in giving barriers to
stop bacteria in entering our body which will make us sick.
The extra step of dissolving the nucleus is needed during DNA replication in a eukaryotic cell, whereas bacteria are prokaryotic and therefore don't have a nucleus so they don't need this extra step.
The root word of Unicellular already tells you the answer. Uni means only one cell. So the answer is one cell.
