* Concentration Gradient: This refers to the difference in concentration of a substance between two areas. Substances naturally move from an area of high concentration to an area of low concentration.
* Passive Transport: This type of transport across cell membranes does not require energy from the cell. The movement is driven by the inherent tendency of molecules to spread out and distribute evenly.
Examples of Passive Transport:
* Simple diffusion: Movement of small, nonpolar molecules directly across the membrane.
* Facilitated diffusion: Movement of molecules across the membrane with the help of transport proteins.
* Osmosis: Movement of water across a semipermeable membrane from an area of high water concentration to an area of low water concentration.
Key takeaway: Passive transport relies on the concentration gradient to provide the driving force for movement, making it an energy-efficient process for cells.
