Endocytosis is common in UNICELLULAR ORGANISMS;
Endocytosis is a form of active transport by which a cell take nutrients or other substances into its cells by invagination of the cell membrane to form vacuole. The cells in the multi cellular organisms usually use this method to take nutrients into their cells.
Endocytosis, which can also be called engulfment is the major means by which unicellular organisms take food particles into their cells.