LC BIOLOGY- OSMOSIS AND DIFFUSION

Selectively Permeable Membrane

allows some but not all molecules to pass through

Diffusion/activite transport

the spreading out of molecules from an area of high concentration to an area of low concentration

Osmosis

the movement of water molecules across a semi-permeable membrane from an area of high water concentration to an area of low water concentration

Solvent

liquid that dissolves other substances

Solute

substance that has been dissolved

Solution

mixture of solvent and solute

Turgor Pressure

the outward pressure of the cytoplasm and vacuole against the cell wall of a plant

Plasmolysis

the loss of water from the cytoplasm and the movement of the cell membrane away from the cell wall

High Salt and Sugar Concentration

• can be used to remove water from microorganisms by osmosis

• are used as food preservation techniques

give one example of active transport have studied

aborption in the small intestine

Using your knowledge of osmosis, explain the application of a high salt or high sugar concentration in food preservation.

water moves by osmosis from microorganism to the high salt does not spoil food

how do plants obtain the minerals they require

osmosis

WHY DO WE USE VISKING TUBING??

to act as a semi periable membrane

WHY DO WE USE DISTILLED WATER

Acts as control against experiment

Plant Cell in Hypotonic Solution (less dissolved solutes than cytoplasm)

• Water enters the cell.

• The cell becomes turgid.

Describe in detail what happens to a plant cell that is placed in a solution with less dissolved solutes than its cytoplasm.

• Water enters the cell

• The cell becomes turgid

Describe what would happen to an animal cell if it was exposed to the same conditions as the plant cell at part (b) (ii) above. Explain your answer.

It would burst

Describe the biological basis and the advantage of having a high salt or sugar concentration in foods (e.g. jam)

• Water leaves the cells of microorganisms present and they die

• Extends the shelf-life of food (or described)

explain passive process

no energy required

under what conditions do osmosis occur

different concentrations either side of the membrane

how would we know omosis occured

increased mass in the more concentrated solution