Final answer:
Facilitated diffusion is a form of passive transport that does not require energy, utilizing carrier or channel proteins to move substances across cell membranes.
Step-by-step explanation:
The process of facilitated diffusion does not require an input of energy. In passive transport, molecules or ions move across the cell membrane down their concentration gradient, from an area of higher concentration to an area of lower concentration, without the need for cellular energy.
Facilitated diffusion makes use of carrier proteins or channel proteins to assist hydrophilic substances, like glucose and ions, in passing through the cell membrane's lipid bilayer due to its hydrophobic properties, which repel polar molecules.
This process is distinct from active transport, where energy in the form of ATP is necessary to move molecules against their concentration gradient.
Facilitated diffusion is the passive movement of molecules along the concentration gradient. It is a selective process, i.e., the membrane allows only selective molecules and ions to pass through it. It, however, prevents other molecules from passing through the membrane.