Osmosis & Diffusion
Observing weight/volume changes in potato cylinders or Visking tubing across sucrose concentration gradients.
STATUS
This lab is in development.
When complete, this will be a guided, step-by-step 3D simulation of the real biology practical. For now, you can read exactly what the simulation will cover below.
What you’ll do
The guided simulation will walk you through these steps in order.
- 01Cut potato cylinders of uniform length and diameter using a cork borer and scalpel; measure and record initial length and mass of each cylinder.
- 02Prepare a series of sucrose solutions of known concentration (e.g. 0, 0.2, 0.4, 0.6, 0.8, 1.0 mol/dm³).
- 03Place one or two potato cylinders into each concentration; leave for at least 30 minutes.
- 04Remove cylinders, blot dry with filter paper, and measure and record final length and mass.
- 05Calculate percentage change in mass for each concentration: ((final − initial) / initial) × 100.
- 06Plot percentage change in mass against sucrose concentration; the point where the graph crosses zero gives the solute concentration of the potato cell sap.
- 07Explain the results in terms of water potential, osmosis, and the relationship between the cell sap and the external solution.