Final answer:
The movement of solutes into a cell from an area of higher concentration to an area of lower concentration through transport proteins is known as facilitated diffusion.
Step-by-step explanation:
The passage of solutes into a cell across a concentration gradient is known as facilitated diffusion. This biological process allows molecular substances to move from an area of higher concentration to one of lower concentration through the cell membrane, with the help of transport proteins. Facilitated diffusion does not require energy and involves specific transmembrane proteins that function either as channels or carriers to move substances, such as glucose or ions, down their concentration gradient. This is in contrast to active transport, where substances move against the concentration gradient and require energy.