Page 13 - 02 Cells Biology Notes

#18 Osmosis

Osmosis is the diffusion of water molecules from a
region of their higher concentration to a region of
their lower concentration, through
a partially permeable membrane.

Osmosis is a special form of diffusion and always involves the movement
of H2O across a membrane. Osmosis is:

• the movement of H2O
• across a selectively permeable membrane
• down a water potential gradient.

In the picture below

- The concentration of sugar molecules is higher on
the concentrated solution (L) and lower on the diluted one (R).

- The concentration of water molecules is higher on the (R) and lower on
the (L) (a lot of place is taken up by sugar molecules).

It is confusing to talk about the 'concentration of water', so we can say
that a diluted solution (R) has a high water potential and a concentrated
solution (L) has a low water potential.