Experiment 14 — The Potato Osmoscope

Topic: Biology · Class 9 · The fundamental unit of life: osmosis and the cell membrane

Aim: Make the water level in the potato cup rise , proving that water moves by osmosis.

Daily: Raisins swell in water, salted cucumber weeps, wilted spinach revives in a bowl of water, and too much fertiliser kills a plant by drawing water out of its roots.

Question: Why is a boiled potato used as a control in this experiment?

Exp: Osmosis needs living selectively permeable membranes; the boiled potato shows what happens without them.

Question: Osmosis is the movement of…

Exp: Water moves; the solute usually cannot.

Question: A plant cell in a strong salt solution will…

Exp: The contents shrink away from the cell wall.

Question: An animal cell placed in pure water may…

Exp: It has no cell wall to resist the swelling.

Question: Salting vegetables preserves them because salt…

Exp: Osmosis dehydrates the microbes too.