The word protista is defined as the first level in some systems of classification of living organisms. It is basically defined as a kingdom which comprises several species of unicellular organisms, which are both animal-like and plant-like. All these organisms have distinct nuclei. Some species of protista include the eukaryotes, which includes protozoa, algae and certain intermediate forms. Blue-green algae and bacteria are not protista. In other systems of classification, protista includes only the protozoa, namely monera.
In other words, the word protista is defined as the kingdom which includes unicellular eukaryotic organisms and also a few multicellular forms, many of which are responsible for causing diseases in human beings. The organisms in this kingdom have a single cell and a true eukaryotic nucleus. They may be either heterotrophic or autotrophic. Autotrophic organisms are those which are able to make their own food. They may either be motile or sessile.
In other words, the word protista is defined as the kingdom which includes unicellular eukaryotic organisms and also a few multicellular forms, many of which are responsible for causing diseases in human beings. The organisms in this kingdom have a single cell and a true eukaryotic nucleus. They may be either heterotrophic or autotrophic. Autotrophic organisms are those which are able to make their own food. They may either be motile or sessile.