Which of the following transport mechanisms is considered a form of bulk transport?

• A. Endocytosis
• B. Simple diffusion
• C. Facilitated diffusion
• D. Osmosis

Answer: (A)

Verified step by step guidance

1. Understand the concept of bulk transport: Bulk transport refers to the movement of large molecules or particles across the cell membrane, typically involving vesicles. It is distinct from passive transport mechanisms like diffusion and osmosis, which move smaller molecules.
2. Review the mechanism of endocytosis: Endocytosis is a form of bulk transport where the cell engulfs external substances by forming vesicles from the plasma membrane. This process allows the cell to take in large molecules or particles.
3. Compare endocytosis with other options: Simple diffusion, facilitated diffusion, and osmosis are passive transport mechanisms that move substances down their concentration gradient without requiring vesicles or energy input. These processes are not considered bulk transport.
4. Identify why endocytosis is the correct answer: Endocytosis involves the active transport of large substances into the cell using vesicles, which is characteristic of bulk transport. The other options do not involve vesicles or the movement of large particles.
5. Conclude that endocytosis is the correct form of bulk transport among the given options, as it aligns with the definition and mechanism of bulk transport.