Animation - How Osmosis Works

Why is diffusion involving water a special case?

Water is necessary for life on earth. Not only is water directly involved in many key biochemical reactions, virtually all the molecular processes of life occur in an aqueous environment. Why is water so important? It is a small, weakly polar molecule. These properties mean that water molecules can pass through cellular membranes but also form solutions with ions and polar molecules. Water is the medium in which the biochemical processes of life occur. This animation shows how the concentration of molecules in solution in water can cause the movement of water across a membrane, otherwise known as osmosis. Preventing the loss or gain of too much water through osmosis is often an important challenge for cells.

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