Here's why:

* Diffusion: The movement of molecules from an area of high concentration to an area of low concentration.

* Facilitated: The process is aided by a membrane protein.

* Membrane protein: A protein embedded in the cell membrane that acts as a carrier or channel.

How it works:

1. Binding: The molecule binds to the membrane protein on one side of the cell.

2. Conformational change: The membrane protein undergoes a change in shape, allowing the molecule to move through the membrane.

3. Release: The molecule is released on the other side of the cell.

Key characteristics of facilitated diffusion:

* Passive transport: It doesn't require energy.

* Down the concentration gradient: Molecules move from high to low concentration.

* Specificity: Membrane proteins are specific to the molecules they transport.

* Saturation: At high concentrations, the transport rate can become saturated because all the membrane proteins are occupied.

Examples of molecules transported by facilitated diffusion:

* Glucose

* Amino acids

* Ions

Let me know if you have any other questions!