Osmosis Biology coursework, please help?

All the natural phenomena observed in nature and other surroundings display either shrinking or expanding in volume, all such phenomena have one thing in common, all these substances are bound by membranes. These membranes can be of any origin, they appear to be continous sheets or films yet contain a network of submicroscopic holes or pores. Small solvent molecules like water can pass through these holes but the passage of bigger molecules like the solute is hindered. Membranes having such kind of properties are known as semi permeable membranes.