How Osmosis In Potatoes Is Affected By Solution Concentration

How Osmosis In Potatoes Is Affected By Solution Concentration

Aim

To investigate how the concentration of a salt and water solution

affects the rate of osmosis in a potato.

Osmosis

Osmosis is the passage of water from an area of high water

concentration to an area of lower water concentration, through a

partially permeable membrane (a membrane which allows small molecules

like oxygen, carbon dioxide, water, ammonia, glucose etc to pass

through, but does not allow larger molecules such as sucrose, starch,

protein etc). Cell membranes are partially permeable, which allows

water to pass from one cell to another within the organism, and also,

as I will be exploring in this investigation, from outside to inside,

or vice versa.

Osmosis occurs when the area of liquid outside the cell contains more

water particles than the area of liquid inside the cell. In the

solution, the particles are moving all the time. In a solution in

which the concentration of water is high, there are more water

particles per cm3 than in a dilute solution, and therefore a higher

rate of movement, causing more particles to come into contact with the

membrane. In a more dilute solution in which there are less water

particles per cm3, less movement occurs and therefore less particles

will pass through the membrane. Also, in the solution with low water

concentration, there are more particles of sugar or in this case salt,

which form a weak attraction with the water particles, inhibiting

movement. Therefore, there will be more water moving from the area of

high water concentration.

This diagram shows how osmosis occurs.

[IMAGE]

The diagram shows an area of high water concentration (on the left)

and one of low water concentration. The dashed line at the centre

represents a partially permeable membrane, while the large red circles

symbolize the salt particles and the smaller blue ones, the water. The

arrows show that there are more water particles moving towards and

through the membrane from left to right (high water concentration to