Question

The cell is taking in substances through membrane proteins, without any energy expenditure of its own. The substances naturally follow their concentration gradient. However, they must go through the protein channels, because they are too large to squeeze through the cell membrane. This process is called A) osmosis. B) endocytosis. C) active transport. D) facilitated diffusion.

Answer 1

Protein channels + no energy spent + following concentration gradient = passive transport via facilitated diffusion :)