d. all of the above
Work Step by Step
Endocytosis, exocytosis, and phagocytosis all involve the actions of vesicles. In endocytosis, the membrane pinches around substances near the cell's surface, forming a vesicle that will take the substances into the cell. With exocytosis, a vesicle that has formed around a substance or substances within the cell travels to the cell's membrane, fuses with it, and then releases its contents to the outside of the cell. Phagocytosis is a type of endocytosis that traps debris, food, or foreign organisms outside of the cell within a vesicle. The vesicle then travels into the cell, meets up with a lysosome and fuses with it, allowing the digestive enzymes within the lysosome to break down the material within the vesicle.