Osmosis – a special Osmosis – a special type of diffusiontype of diffusion

Lesson objectiveLesson objective

I will know what osmosis isI will know what osmosis is

MethodMethod

Using a cork borer, collect 3 equal Using a cork borer, collect 3 equal 2cm pieces of potato.2cm pieces of potato.

Cut each length into 10 slicesCut each length into 10 slices Weigh each set of 10 slicesWeigh each set of 10 slices Place each set in different solutions Place each set in different solutions

(0.3M, 1.0M sucrose and distilled (0.3M, 1.0M sucrose and distilled water)water)

Leave for 20 minutes and reweigh. Leave for 20 minutes and reweigh.

ResultsResults

SolutionSolution Mass Mass Before Before (g)(g)

Mass Mass After After (g)(g)

Mass Mass DifferencDifference (g)e (g)

0.3M sucrose0.3M sucrose

1.0M sucrose1.0M sucrose

Distilled waterDistilled water

DiffusionDiffusion

is the spreading of the particles is the spreading of the particles of any substance in solution, of any substance in solution, resulting in a net movement from resulting in a net movement from a region where they are of a a region where they are of a higher concentration.higher concentration.

(end up with even spread of (end up with even spread of particles)particles)

Make a prediction as to whether Make a prediction as to whether each set will either lose mass, each set will either lose mass, gain mass or stay the same.gain mass or stay the same.

OsmosisOsmosis

The movement of water from a dilute The movement of water from a dilute to a more concentrated solution to a more concentrated solution through a partially permeable through a partially permeable membrane that allows the passage membrane that allows the passage of water but not solute molecules.of water but not solute molecules.

Osmosis is passive this means it does Osmosis is passive this means it does not need energynot need energy

You need to write

this!

OsmosisOsmosis

Dilute Solution

Concentrated Solution

Solute

Water

Net movement of water

The water will move into the concentrated solution until both are equal. The solutions are said to be ISOTONIC

OsmosisOsmosis

Water inside plants gives support to the plant.Water inside plants gives support to the plant.

When water moves into the cell by osmosis it When water moves into the cell by osmosis it increases the pressure inside the cell.increases the pressure inside the cell.

The cell walls are strong enough to withstand The cell walls are strong enough to withstand this pressure.this pressure.

It is this pressure that keeps the cells turgid It is this pressure that keeps the cells turgid and hence supplies support.and hence supplies support.

You need to write

this!

Illustrate with diagrams to Illustrate with diagrams to describe how water moved describe how water moved across a semi-permeable across a semi-permeable membrane in each casemembrane in each case

ConclusionConclusionPotato0.3M Potato1.0M

PotatoWater

No net movement - Isotonic

Potato loses mass - flaccidPotato gains

mass - turgid

SucroseWater