Facilitated diffusion is a type of
A. passive transport
B. exocytosis
C. active transport
D. endocytosis
A. passive transport
A. passive transport
To determine the type of transport facilitated diffusion is, we need to understand the process of facilitated diffusion.
Facilitated diffusion is the movement of molecules across the cell membrane with the help of transport proteins. These proteins create channels or carrier proteins that allow specific molecules to pass through the membrane, down their concentration gradient.
Now, let's analyze the answer choices:
A. Passive transport - Passive transport is the movement of molecules across the cell membrane without the use of energy. In facilitated diffusion, although it requires the presence of transport proteins, it still does not require the expenditure of energy. Therefore, facilitated diffusion is a type of passive transport.
B. Exocytosis - Exocytosis is the process by which cells release materials to the outside by fusing vesicles with the cell membrane. Facilitated diffusion does not involve the release of materials but rather the movement of specific molecules across the membrane.
C. Active transport - Active transport is the movement of molecules across the cell membrane using energy from ATP. Facilitated diffusion does not require the expenditure of energy, as it relies on the concentration gradient.
D. Endocytosis - Endocytosis is the process by which cells engulf external material by forming a vesicle around it and bringing it into the cell. Facilitated diffusion does not involve the engulfing of materials but rather the selective movement of specific molecules through transport proteins.
Therefore, the correct answer is A. passive transport.