Water potential is a measure of the pressure exerted by water molecules on the membrane or container surrounding a solution.

Pure water has a water potential of 0 kPa.

Adding a solute to water lowers the water potential, making it more negative.

Osmosis is the movement of water molecules from a higher water potential to a lower water potential through a partially permeable membrane.

A hypertonic solution has a lower water potential than the animal cell, so water molecules move out of the cell, causing the cell to shrink.

A hypotonic solution has a higher water potential than the animal cell, so water molecules move into the cell, causing the cell to swell and burst.

An isotonic solution has the same water potential as the animal cell, so there is no net movement of water and the cell stays the same size.

A hypertonic solution has a lower water potential than the plant cell, so water molecules move out of the cell, causing the cell to shrink and become plasmolysed.

A hypotonic solution has a higher water potential than the plant cell, so water molecules move into the cell, causing the cell to swell and become turgid. 

1. Temperature
2. Water potential gradient 
3. Thickness of membrane
4. Surface area 

Osmosis is a passive process because it doesn’t require any energy from the cell.

From outside the cell to inside the cell, because there's a greater concentration of water outside the cell.

Plant cells have a strong cell wall made of cellulose, which prevents them from bursting.

The water potential will decrease.