Passive Transport Simple and Facilitated diffusion, Osmosis Class 11

Passive transport is the movement of molecules across a cell membrane without the use of energy. It occurs naturally, driven by concentration gradients and random motion of molecules. There are three main types of passive transport: 1. *Simple Diffusion*: Molecules move from an area of high concentration to an area of low concentration until equilibrium is reached. 2. *Osmosis*: Water molecules move through a selectively permeable membrane from an area of high concentration to an area of low concentration, equalizing solute concentrations. 3. *Facilitated Diffusion*: Molecules use transport proteins to move across the membrane, driven by concentration gradients. Key characteristics of passive transport: No energy required Moves down concentration gradients Random motion of molecules No active pumping or transport against gradients Examples of passive transport include: Oxygen entering cells and carbon dioxide leaving cells through diffusion Water moving into or out of cells through osmosis Glucose entering cells through facilitated diffusion