Rising sap

Make a deep hole in a carrot and fill it with water in which you have dissolved plenty of sugar. Close the opening firmly with a bored cork, and push a plastic straw through the hole.

Mop up any overflowing sugar solution, and seal the joints with melted candle wax. Put the carrot into water and watch: after some time the sugar solution rises into the straw.

The water particles can enter the carrot through the cell walls, but the larger sugar particles cannot come out. The sugar solution becomes diluted and rises up the tube. This experiment on osmosis illustrates how plants absorb water from the soil and carry it upwards.