passive transport

Passive transport is the movement of substances across a cell membrane without the use of energy. This process relies on the principle of diffusion, where substances move from an area of high concentration to an area of low concentration.123

There are two main types of passive transport:
* Diffusion: Small molecules and lipid-soluble substances can pass directly through the cell membrane.2
* Facilitated diffusion: This involves membrane proteins that help specific solutes move across the membrane down their concentration gradient.2

Passive transport is crucial for cells to exchange essential nutrients and waste products with their environment. It contrasts with active transport, which requires energy to move substances against their concentration gradient.231