Which of the following is a mechanism of carrier-mediated transport?

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

Answer: (A)

Verified step by step guidance

1. Understand the concept of carrier-mediated transport: Carrier-mediated transport involves the movement of substances across cell membranes with the help of specific proteins known as carriers.
2. Identify the types of transport mechanisms: Carrier-mediated transport can be either passive or active. Passive transport does not require energy, while active transport does.
3. Examine facilitated diffusion: Facilitated diffusion is a type of passive transport where substances move across the cell membrane through carrier proteins, down their concentration gradient, without the use of energy.
4. Differentiate facilitated diffusion from other options: Simple diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration without the use of carrier proteins. Endocytosis is a form of active transport where the cell engulfs material. Osmosis is the diffusion of water across a semipermeable membrane.
5. Conclude that facilitated diffusion is the correct mechanism of carrier-mediated transport: Facilitated diffusion specifically involves carrier proteins, making it a mechanism of carrier-mediated transport.