Osmosis
Understand the process of osmosis. Know the effects of osmosis on plant and animal cells.
Osmosis
This
is a special kind of diffusion involving water molecules only.
A solution such as cytoplasm or tissue fluid consists of a solvent such as water and a solute such glucose or salt. Osmosis
It is the net movement of water across a partially permeable membrane from an area of high water concentration to an area of low water concentration.
High
lower
Osmosis
In
a dilute solution the solute is at a low concentration and the solvent
(water) is at a high concentration.
Solute
Water
(solvent)
Osmosis
In
a concentrated solution the solute is at a high concentration and the solvent (water) is at a low concentration. Solute
Water
(solvent)
Osmosis and water potential Solutions
with a high water concentration are said to have a high water potential (WP or )
Solutions
with a low water concentration are said to have a low water potential (WP or )
Why does osmosis occur? High
At high water molecules have more energy because they are less restricted by presence of solutes. Low
At low water molecules have less energy because they are partially permeable more restricted by presence of membrane solutes.
Why does osmosis occur? more water
less water
High
Low
More water molecules can diffuse from left to right (high to low ) than from right to partially permeable left. membrane
Water potential
The
higher the water potential the greater the energy of water molecules and the more likely they are to move by osmosis.
At standard temperature and pressure the of pure water is ZERO.
So, the addition of solutes lowers , and so makes the more negative.
Your turn to look at
5
osmosis minutes 1.
2.
3.
4.
5.
6.
7.
Cut two potato cylinders of the same diameter and trim to
3cm in length.
Measure and record the length and weight of each of the