Introduction (from Wikipedia). The Archaea constitute a domain or kingdom of single-celled microorganisms. These microbes are prokaryotes, meaning that they have no cell nucleus or any other membrane-bound organelles in their cells. Bacteria constitute a large domain of prokaryotic microorganisms.ut it was discovered that archaea have a distinct evolutionary history and biochemistry compared with bacteria. The similarities are that archaea and eubacteria are single-celled organisms that do not have a nucleus or organelles.
cohort noun [C ]. âº a âgroup of âpeople who âshare a characteristic, usually age: About 42% of women in this age cohort have a college degree. This year's cohort of âgraduates will have particular difficulties âfinding âjobs.ohort noun [C ]. âº a âgroup of âpeople who âshare a characteristic, usually age: About 42% of women in this age cohort have a college degree. This year's cohort of âgraduates will have particular difficulties âfinding âjobs.
In this respect, a cohort study is often interchangeable with the term naturalistic observation. There are two main sub-types of cohort study, the retrospective and the prospective cohort study. The major difference between the two is that the retrospective looks at phenomena that have already happened, whilst the prospective type starts from the present. . The retrospective case study is historical in nature.