Essay Experiment to Investigate Osmosis in Potatoes

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Experiment to Investigate Osmosis in Potatoes The aim of this experiment is to investigate the movement of water in and out of plant cells. The cells chosen for study will be taken from potato tubers. Firstly I will explain what osmosis is. Osmosis is the passage of water from a region of high water concentration through a semi permeable membrane to a region of low water concentration. This definition contains three important statements: a) It is the passage of water through a semi permeable membrane b) It is the passage of water from a region of high water concentration c) It is the passage of water to a region of low water concentration. All the above statements are included in the definition, but define certain…show more content…
Transpiration pulls water up the plant stem but osmosis is the process whereby water is drawn into or out of cells and tissues. Osmosis is the flow of water by diffusion through a differentially permeable membrane from areas of high water concentration to regions of low water concentration. The diagram below illustrates this: Water can freely penetrate all membrane. The cellulose cell wall does not act as a semi permeable membrane and will allow most substances that are dissolved in water to freely pass through it. Whether water enters the cell by osmosis or not will depend on the balance between external and internal solute concentrations and the state of the cell. If the solutions on each side of the differentially permeable membrane are equally concentrated then there will be no net movement of water across the membrane. This is called an equilibrium state and the solutions are referred to as being isotonic. A solution that contains more solute particles than another, and is hence more concentrated, is referred to as being hypertonic. The less concentrated solution is hypotonic. This concentration of solute particles is usually described as a molarity. Even if the solute concentration external to the cell is hypotonic to the vacuole contents the cell will not continue to take in water by osmosis for ever. The cellulose cell wall provides a rigid barrier to uncontrolled expansion. A cell that is full of water
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