Endocytosis is a cellular mechanism by which, a cell internalizes substances including proteins, fluids, electrolytes, microorganisms, and some macromolecules, from its external environment. These substances undergo certain processes of breaking down to smaller elements either for use by the cell or for elimination purposes.

Answer: Animals are the only organisms that undergo endocytosis because they lack a cell wall. As a result, in animals as opposed to plants, the flow of chemicals within the cell is simpler. Explanation: The act of a plasma membrane engulfing food and other substances from an external medium is known as endocytosis.