Passive transport

Definition

Passive transport is the movement of molecules across a cell membrane without the use of cellular energy. It relies on the concentration gradient to drive the movement of substances from areas of higher concentration to areas of lower concentration.

5 Must Know Facts For Your Next Test

1. Passive transport includes processes such as diffusion, osmosis, and facilitated diffusion.
2. It does not require ATP or any other form of energy input from the cell.
3. Small nonpolar molecules, like oxygen and carbon dioxide, typically move easily through passive transport.
4. Facilitated diffusion involves carrier proteins or channel proteins in the cell membrane to move larger or polar molecules.
5. The rate of passive transport can be influenced by factors such as temperature, molecule size, and the steepness of the concentration gradient.

Review Questions

• What are three types of passive transport?
• How does facilitated diffusion differ from simple diffusion?
• What role does the concentration gradient play in passive transport?

Related terms

Diffusion: The movement of particles from an area of higher concentration to an area of lower concentration.

Osmosis: The diffusion of water across a selectively permeable membrane.

Facilitated Diffusion: A type of passive transport that uses carrier proteins or channel proteins to help move substances across the cell membrane.