Which of these statements describes some aspect of facilitated diffusion?

• A. Facilitated diffusion is another name for osmosis.
• B. Facilitated diffusion of solutes occurs through phospholipid pores in the membrane.
• C. Facilitated diffusion requires energy to drive a concentration gradient.
• D. There is only one kind of protein pore for facilitated diffusion.
• E. Facilitated diffusion of solutes may occur through channel or transport proteins in the membrane.

Answer: (E)

Verified step by step guidance

1. Facilitated diffusion is a type of passive transport, meaning it does not require energy input from the cell. It relies on the concentration gradient to move substances across the cell membrane.
2. In facilitated diffusion, specific molecules are transported across the cell membrane with the help of transport proteins. These proteins can be either channel proteins or carrier proteins.
3. Channel proteins form pores in the cell membrane, allowing specific molecules or ions to pass through by diffusion. These channels can be gated, opening or closing in response to certain stimuli.
4. Carrier proteins bind to the molecules they transport, undergoing a conformational change to move the molecule across the membrane. This process is selective and specific to the molecules being transported.
5. Facilitated diffusion is distinct from osmosis, which is the diffusion of water across a semipermeable membrane. It also differs from active transport, which requires energy to move substances against their concentration gradient.