Osmosis Lab

Mrs. Pfahnl’s Bio A Lab: Osmosis

Osmosis is a passive transportation of water molecules through semipermeable cell membrane.

The purpose of the experiment is to investigate the different salt levels affects the intake or output of the water molecules of plant cells.


1. Four narrow cups which can at least hold one cup of water

2. Measure cup of 1 cup, half a teaspoon, 1 teaspoon
3. Two Large (white, yellow or sweet) potatoes at least 2 inches long
4. Table salt
5. Cutting knife and cutting board
6. Gloves to protect your hands
7. Ruler


1. Label the 4 cups 1, 2, 3, 4
2. Add ½ tsp salt in cup 2
3. Add 1 tsp salt in cup 3
4. Add 2 tsp salt in cup 4
5. Add 1 cup of water to every cup
6. Mix salt with water by stirring with a spoon in the order of cup 2, 3 and 4
7. Cut one potato in half along the length
8. Cut into about 1 cm thickness
9. Cut into 1 cm strips
10. Cut the ends of the strips to 6 cm long
11. Put 3 strips in each cup
12. Measure length at ½h, 1h, 2h, 4h, 24h