Final answer:
Exocytosis is the process used by cells to transport large molecules out of the cell, requiring energy to proceed, hence an active transport mechanism.
Step-by-step explanation:
The means by which a cell transports large molecules out of the cell is called exocytosis. This process involves the fusion of vesicles containing these large molecules with the plasma membrane, allowing the contents to be released outside of the cell. It is a form of active transport because it requires energy to move these substances against their concentration gradient.
Endocytosis is the opposite process, where large particles are engulfed by the cell, forming a vesicle within the cytoplasm. While diffusion and osmosis involve the passive movement of small molecules, and phagocytosis involves a cell engulfing large particles, exocytosis is the specific mechanism utilized to export large molecules from the cell.