IMMUNOLOGY

Detailed explanation-1: -The smallest members of the domain Bacteria known to date are found in the following phylogenetic groups: Proteobacteria, Chlamydia, Gram-positive bacteria, Spirochetes, and Verrucomicrobia.

Detailed explanation-2: -Mycoplasma gallicepticum, a parasitic bacterium is thought to be the smallest known organisms with the size from 0.2 to 0.3 micrometer, capable of independent growth and reproduction.

Detailed explanation-3: -The smallest cell is Mycoplasma gallicepticum. It is about 10 micrometer in size. The largest cells is an egg of ostrich. It is about 15 to 18 cm long and wide.

Detailed explanation-4: -Adenovirus is the smallest virus and Mycoplasma is the smallest bacteria.