diffusion and osmosis

• diffusion is the gradual movement of particles from an area of high concentration to an area of low concentration
• diffusion happens in solutions and gasses as particles are free to move about randomly
• dissolved substances can move in and out of cells by diffusion
• only very small molecules can diffuse through cell memebranes- such as oxygen (needed for respertation), glucose, amino acids, and water
• just like diffusion in air, particles flow from a high concentration to a low low concentration
• larger SA of cell memebrane = faster diffusion rates as more particles can pass through at once
• osmosis is the movement across a partially permeable membrane from a region of higher water concentration to a region of lower water concentration
• a partially permeable memebrane allows some substances to pass through it but not all as is has small holes