GCSE Biology Required Practical

Potato Cylinder Osmosis Simulator

Investigate how sucrose concentration affects percentage change in mass.

Virtual Lab Bench

Run a 24-hour time-lapse across six sucrose concentrations.

Estimated isotonic point: 0.35 mol/dm3

Time elapsed: 0 h Ready

Results and Graph

Plot of % change in mass vs sucrose concentration.

Run the practical to generate data points and a trend line.

Sucrose (mol/dm3)	Initial Mass (g)	Final Mass (g)	% Change

Method Notes

Each cylinder starts close to 5 g to mimic matched potato cores.
Lower sucrose concentrations usually cause a gain in mass.
Higher sucrose concentrations usually cause a loss in mass.
Formula used: ((final - initial) / initial) x 100.
The isotonic point is where the graph crosses 0% change in mass.

Osmosis Explanation Simulator

Explore how a concentration gradient causes net water movement across a partially permeable membrane.

Semi-permeable membrane

Equal Concentration Equal Concentration

Left Water Level

Right Water Level

Left Solute: 10 Right Solute: 10

Water Solute

What is osmosis?

Osmosis is the net movement of water molecules from a dilute solution (higher water potential) to a more concentrated solution (lower water potential) through a partially permeable membrane.

Water molecules can pass through membrane gaps, but solute particles cannot.
Water moves in both directions, but net movement is toward the more concentrated side.
Net movement slows as the concentration difference becomes smaller.

Both sides currently have equal solute concentration, so there is no net water movement.

Increase solute on one side to see net water movement toward the more concentrated side.