Can you work it out?

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