PATHOLOGY

Detailed explanation-1: -Bacteria are single celled microbes that lack a nucleus. Archaea are like bacteria, but they have different structures and properties. This gives them the ability to live in extreme environmental conditions. Protozoa are unicellular microorganisms that have nuclei.

Detailed explanation-2: -But if we look for the simplest creatures on the planet, we will find a wee bacterium that lives happily in the digestive tracts of cows and goats: Mycoplasma mycoides. It builds itself from a very modest blueprint-only 525 genes. It’s one of the simplest life-forms we’ve ever seen.

Detailed explanation-3: -Bacteria lack a membrane-bound nucleus and other internal structures and are therefore ranked among the unicellular life-forms called prokaryotes.