A provisional group in which are placed a number of low microscopic organisms of doubtful nature. Some are probably plants, others animals.
Organisms in this Kingdom are unicellular and have a true nucleus (eukaryotic). They may be heterotrophic or autothrophic (able to make their own food). They may also be motile or sessile.
The third kingdom, next to the kingdoms of plants and animals, in the classification of living organisms. The Protista include all organisms that do not have any extensive development of tissues, such as algae, fungi, protozoa and bacteria.
a kingdom that includes protozoa, one-celled algae, and slime molds.
kingdom encompassing all unicellular organisms which possess cells with a true nucleus.
eukaryotic one-celled living organisms distinct from multicellular plants and animals: protozoa, slime molds, and eukaryotic algae
pro-TEES-ta The kingdom that includes unicellular, eukaryotic organisms, the protista. 14, 429
The taxonomic Kingdom from which the other three eukaryotic kingdoms ( Fungi, Animalia and Plantae) are thought to have evolved. The earliest eukaryotes were single-celled organisms that would today be placed in this admittedly not monophyletic group. The endosymbiosis theory suggests that eukaryotes may have evolved independently several times.
Protista, a Greek word meaning "primitive" or "first," is the third kingdom in the classification of life forms. Protista consists of single-celled microbes -- such as algae, bacteria, fungi, and protozoa -- and multicellular organisms that are not differentiated (organized) into distinct tissues and organs, as are higher animals and plants.
Group, at the kingdom level, in the classification of life. Organisms that are mainly unicellular and have a eukaryotic cell type. A few multicellular members exist.