Osmosis

Osmosis is a special way that water moves. It happens when water passes through a thin barrier called a membrane. Water moves from where there are fewer dissolved particles to where there are more. This process is very important for keeping the cells in your body healthy.

How Osmosis Works

Imagine a membrane with salt water on one side and fresh water on the other. The membrane lets water through but not salt. Water molecules move from the fresh water side to the salty side, trying to balance things out. This movement of water through a membrane is osmosis.

Osmosis in Living Things

Every cell in your body is surrounded by a membrane. Osmosis keeps the right amount of water inside each cell. Plant roots absorb water from the soil through osmosis. If you put a wilted lettuce leaf in fresh water, osmosis moves water into the cells and the leaf perks up again.

Fun Facts

• Slug and snails shrivel up when you put salt on them because osmosis pulls water out of their bodies.
• Soaking dried beans in water uses osmosis to plump them up before cooking.
• Reverse osmosis is used to turn salt water into fresh drinking water.

Did You Know?

Prunes are made from plums that have been dried. If you soak a prune in water overnight, osmosis makes it plump up almost back to the size of the original plum!