<P> Simple diffusion and osmosis are in some ways similar . Simple diffusion is the passive movement of solute from a high concentration to a lower concentration until the concentration of the solute is uniform throughout and reaches equilibrium . Osmosis is much like simple diffusion but it specifically describes the movement of water (not the solute) across a selectively permeable membrane until there is an equal concentration of water and solute on both sides of the membrane . Simple diffusion and osmosis are both forms of passive transport and require none of the cell's ATP energy . </P> <P> Facilitated diffusion, also called carrier - mediated osmosis, is the movement of molecules across the cell membrane via special transport proteins that are embheir plasma membrane by actively taking up or excluding ions . Active transport of protons by H ATPases alters membrane potential allowing for facilitated passive transport of particular ions such as Potassium down their charge gradient through high affinity transporters and channels . </P> <P> Filtration is movement of water and solute molecules across the cell membrane due to hydrostatic pressure generated by the cardiovascular system . Depending on the size of the membrane pores, only solutes of a certain size may pass through it . For example, the membrane pores of the Bowman's capsule in the kidneys are very small, and only albumins, the smallest of the proteins, have any chance of being filtered through . On the other hand, the membrane pores of liver cells are extremely large, but not forgetting cells are extremely small to allow a variety of solutes to pass through and be metabolized . </P> <P> Osmosis is the movement of water molecules across a selectively permeable membrane . The net movement of water molecules through a partially permeable membrane from a solution of high water potential to an area of low water potential . A cell with a less negative water potential will draw in water but this depends on other factors as well such as solute potential (pressure in the cell e.g. solute molecules) and pressure potential (external pressure e.g. cell wall). There are three types of Osmosis solutions: the isotonic solution, hypotonic solution, and hypertonic solution . Isotonic solution is when the extracellular solute concentration is balanced with the concentration inside the cell . In the Isotonic solution, the water molecules still moves between the solutions, but the rates are the same from both directions, thus the water movement is balanced between the inside of the cell as well as the outside of the cell . A hypotonic solution is when the solute concentration outside the cell is lower than the concentration inside the cell . In hypotonic solutions, the water moves into the cell, down its concentration gradient (from higher to lower water concentrations). That can cause the cell to swell . Cells that don't have a cell wall, such as animal cells, could burst in this solution . A hypertonic solution is when the solute concentration is higher (think of hyper - as high) than the concentration inside the cell . In hypertonic solution, the water will move out, causing the cell to shrink . </P>

What is the difference between diffusion and passive transport