Introduction
Protists are eukaryotes and include unicellular (e.g., amoeba) and multicellular forms (e.g., algae). The word protista (Gr. protos, very first, ktistos, to establish) implies great antiquity. Protista represent a polyphyletic group. Two interesting scenarios regarding the history of life on earth emerged during the evolution of protists: the origin of the eukaryotic cell and the subsequent emergence of multicellular eukaryotes.
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