Final answer:
Phagocytosis ('cell eating') is the process where a cell engulfs large solid materials, while pinocytosis ('cell drinking') involves the cell engulfing materials dissolved in solution. Pinocytosis is responsible for the uptake of small dissolved molecules into vesicles.
Step-by-step explanation:
When a cell engulfs large solid materials, it is known as phagocytosis, which is a form of endocytosis where large particles such as macromolecules, parts of cells, or even whole cells are enveloped by the cell membrane and brought into the cell. This process is used by immune cells to engulf and digest invading pathogens. The plasma membrane extends to form pseudopodia that surround the material, creating a phagocytic vesicle, which is later digested with the help of lysosomes.
In contrast, when a cell engulfs materials dissolved in solution, it is referred to as pinocytosis, also known as "cell drinking." During pinocytosis, the plasma membrane folds inward to form a channel allowing dissolved substances to enter the cell. The vesicle that forms, known as a pinocytic vesicle, then detaches and moves into the cytoplasm for processing.
The type of nutrient uptake involving the engulfment of small dissolved molecules into vesicles is pinocytosis. Both phagocytosis and pinocytosis require ATP to fuel the transport of materials into the cell.