Water Potential of a Potato.
Investigating the Water Potential of a Potato.
I have been asked to investigate the water potential of a potato. During my investigation I will not actually be able to measure a value for, as it is a pressure value (kPa).
Osmosis is a special form of diffusion involving only water molecules. It is defined as "The passage of water from a region of high water potential to a region of low water potential through a partially permeable membrane"
Definition of Water Potential.
The potential for water to move across a selectively permeable membrane, where the osmotic potential of distilled water is 0 (kPa) and any water movement is measured with a negative value.
When a solute is mixed with a solvent the water potential will decrease, and will always be a negative value.
Solute Potential.
As the presence of a solute lowers the water potential, the more concentrated the solute is, the lower the water potential will be.
Pressure Potential.
This is if pressure where applied to a solution it would resist the movement of water. There is an equation that can represent to relationship of water potential, solute potential and pressure potential:
= s + p
Osmosis and Plant Cells
Like animal cells, plant cells contain a number of solutes. When these cells are put into pure water, water moves into the cell because there is a lower water potential in the cell. But unlike animal cells, plant cells cannot control the amount of fluid surrounding the cell.
If a plant cell is placed in a solution with a lower water potential than the plant cell, water will move leave the cell, and the cell becomes plasmolysed (flaccid).
If the plant cell is place in a solution with the same water potential, there will be no net movement of water. The cell is then said to be incipient plasmolysis.
The table below shows what happens to the cell when water moves in and out of a cell.
Water potential of solution compared to cell Higher Equal Lower
Net movement of water Enters cell Neither
I have been asked to investigate the water potential of a potato. During my investigation I will not actually be able to measure a value for, as it is a pressure value (kPa).
Osmosis is a special form of diffusion involving only water molecules. It is defined as "The passage of water from a region of high water potential to a region of low water potential through a partially permeable membrane"
Definition of Water Potential.
The potential for water to move across a selectively permeable membrane, where the osmotic potential of distilled water is 0 (kPa) and any water movement is measured with a negative value.
When a solute is mixed with a solvent the water potential will decrease, and will always be a negative value.
Solute Potential.
As the presence of a solute lowers the water potential, the more concentrated the solute is, the lower the water potential will be.
Pressure Potential.
This is if pressure where applied to a solution it would resist the movement of water. There is an equation that can represent to relationship of water potential, solute potential and pressure potential:
= s + p
Osmosis and Plant Cells
Like animal cells, plant cells contain a number of solutes. When these cells are put into pure water, water moves into the cell because there is a lower water potential in the cell. But unlike animal cells, plant cells cannot control the amount of fluid surrounding the cell.
If a plant cell is placed in a solution with a lower water potential than the plant cell, water will move leave the cell, and the cell becomes plasmolysed (flaccid).
If the plant cell is place in a solution with the same water potential, there will be no net movement of water. The cell is then said to be incipient plasmolysis.
The table below shows what happens to the cell when water moves in and out of a cell.
Water potential of solution compared to cell Higher Equal Lower
Net movement of water Enters cell Neither