Advanced Placement (AP) Biology Practice Exam

Food vacuoles are formed by which process?

1. Exocytosis

2. Phagocytosis

3. Pincytosis

4. Receptor-mediated endocytosis

The correct answer is: Phagocytosis

Food vacuoles are formed through the process of phagocytosis, which is specifically designed for the uptake of large particles, such as food or pathogens, by cells. During phagocytosis, the cell membrane engulfs the particle, folding around it and enclosing it within a vacuole. This vacuole then typically fuses with a lysosome, where the contents can be broken down by enzymes for digestion and use by the cell. Phagocytosis plays a crucial role in nutrient uptake for single-celled organisms and in the immune response for multicellular organisms, as it allows cells to engulf and destroy foreign materials. This process is fundamental to cellular nutrition and is distinctly different from other forms of endocytosis, such as pinocytosis, which involves the uptake of liquids and small dissolved substances, or receptor-mediated endocytosis, which relies on specific receptor-ligand interactions to bring in particular molecules.