All living things are made of cells which are differentiated to perform different functions
Substances move into or out of the cell and enzymes are catalysts contributing to cell metabolism
Osmosis
The movement of water molecules across a selectively permeable membrane from a region of higher water concentration to a region of lower water concentration
Osmosis experiment with potatoes
1. Cut equal-sized pieces of potato
2. Blot with tissue paper and weigh
3. Put pieces into different concentrations of sucrose solution for a few hours
4. Remove, blot with tissue paper and reweigh
Percentage change in mass
Calculated as (end mass - start mass) / start mass x 100
The most accurate arithmetic mean can be calculated by excluding outliers
Concentration of sucrose solution
Percentage change in mass of potato
Where the line crosses the horizontal axis at 0% change in mass, the sucrose concentration is equal to the concentration of the contents of the potato cells
There is no net movement of water by osmosis when the water concentration is equal inside and outside the potato cells
Low concentrations of sucrose
Percentage change in mass increases (water moves into potato cells)
High concentrations of sucrose
Percentage change in mass decreases (water leaves potato cells)
