Investigating the Effect of Osmosis on Potato Cylinders

Aim: To investigate the effect of osmosis on the potato cylinders of a
certain size in different concentrations of solution.


· Water will flow from the low concentration to the high

· The cylinders in high concentration solution will gain and increase
in mass.

· The cylinders in low concentration solution will loose and decrease
in mass.

Scientific Knowledge:


Osmosis, which is regarded as a form of diffusion, is defined as the
net movement of water or any small molecule across a partially
permeable membrane from a region of low concentration to a region of
higher concentration.

Partiallypermeable membranesare very thin layers of material (cell
membranes are partially permeable) which allow some things to pass
through them but prevent other things from passing through.

Partially permeable membranes will allow small molecules like Oxygen,
water, Carbon Dioxide, Ammonia, Glucose, amino-acids, etc. to pass
through. Cell membranes will not allow larger molecules like Sucrose,
Starch, protein, etc. to pass through.


When osmosis occurs in a plant cell after it has been watered the
water (which is less concentrated) enters the vacuole which therefore
results in that the vacuole is erected to its full size, this is
called turgidity. When all cells in the plant are turgor this brings
about a noticeable change in the plant, it stands in a healthy way
spreading its leaves out like an umbrella.


When the plant is put in a solution that is more concentrated than it,
it loses the water stored in its vacuoles and therefore becomes
Plasmolysed. When this happens, which never occurs naturally, the
plant becomes weak, dry and limp

The flow of water across a membrane in the process of osmosis
generates a pressure across the membrane called osmotic pressure.
Osmotic pressure is defined as the hydrostatic pressure required to