Amoeba acquires it food by endocytosis, that is, a small region in the plasma membrane which ultimately forms a intra-cellular membrane-bound vescicle. It engulfs it food using its pseudopodia (temporary protrusion of the surface of the amoeboid cell used for feeding and movement) and forms a vacuole around it. When the food is already trapped inside, it releases a digestive enzyme to digest it. Intake of liquid particles is pinocytosis (cell drinking) while intake of solid particles is phagocytosis (cell eating).
It provides protection for the plant cell and supports the shape of the cell.