Investigate the Cell Sap Concentration of Solute in a Potato Chip using Osmosis

Investigate the Cell Sap Concentration of Solute in a Potato Chip using Osmosis

Aim

The aim of the experiment is to investigate the cell sap concentration of solute in a potato chip using osmosis and produce a figure informed by the investigation as to what this is.

Background Information

A factor that effects how much water moves into a cell is the solute concentration within it. Water moves in and out of cells by diffusion, this diffusion is called osmosis. Osmosis is the diffusion of water molecules from a place with a high water potential or high concentration of water to a low water potential or low concentration of water. If a solution has a high water potential this means it is weak or dilute solution so it only has a small solute (e.g. glucose) concentration. However, if a solution has a low water potential it is a strong more concentrated solution because it has a much higher solute concentration. Osmosis is the diffusion of water in these solutions from a high water potential to a low water potential or in terms of solute concentrations, from a dilute solution to a more concentrated solution as a more concentrated solution would have a much lower water potential that a dilute one. The water passes through what is known as a partially permeable membrane, which basically is what separates living cells from their surrounding. The membrane is called partially permeable and not fully permeable because it only allows water to diffuse through it and not solute. The cell wall is an example of a fully permeable membrane because it allows water and solute to pass through it, it does not block any of these molecules.

The diffusion of water molecules by osmosis always flows down a water potential gradient, which basically means from a high to a low water potential this is how the water moves up through a plant in the xylem vessels, once one cell is full of water, the water will move all at once to the next cell. The water is moving from a place of high concentration to a place of low concentration, like the valves in our hearts stop our blood flowing back the other way, the cell membrane of the cell make sure the water only flows up the plant, this is known as the transpiration stream. When water is lost through the stomata this leaves empty cells with low water potentials therefore the water is always moving up the plant from higher water potentials to ...

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...nt parts of the potato as they may have different solute concentration and it may be discovered that the point of no net movement will be different in different areas of the potato or even in different areas of the same chip. The smaller the potato slices from the different areas of the potato then the more detailed an analysis could be of which part of the potato has the highest/lowest % solute concentration.

The experiment could be done again using smaller concentrations, say with a range of 5%-7% and at intervals of 0.25% this way a figure for the actual % solute concentration in a potato chip could be pin-pointed to a much more exact figure.

Finally an experiment could be done using different types of potatoes to decipher whether the type of potato depends on the % solute concentration it has. The trends could be taken for many types of potato and then an average taken of them to give a figure which most represents the solute concentrations in many potatoes. This figure could then be compared or even investigated at the same time as an experiment to see if there were different solute concentrations in different parts of the potato and the links, if any, between them

analysed.