Diffusion
Diffusion is the movement of particles from an area of high concentration to an area of low concentration. The diffusion process will continue until both areas have the same number of particles. An examples of diffusion when you pour food coloring into a cup of water. The food colouring mixes with the water and the water changes colour to the same colouring as the food colouring. Also when you smell pizza in the air, the smell of the pizza is mixing with the air, that's also called diffusion. For the cell, diffusion is how the resource(such as oxygen) moves through the cell's selectively permeable membrane. The selectively permeable membrane is when the membrane only lets certain things through such as water and nutrients. This is how the cell gets its nutrients and one of the steps it needs to survive. So diffusion is when solute particles move and mix with the water particles.