Essay On Water Potential

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Water potential is often represented by the Greek letter, psi ψ .The higher the rate of collisions of the water molecules with the membrane, the greater the pressure on it. This pressure is called water potential. Water always moves from higher water potential to lower water potential. The standard unit for water potential is kilopascals (kPa), which is also the unit pressure. Pure water is designated a water potential of zero which has the highest water potential under atmospheric pressure at 25°C. (Source by: Understanding Biology for Advanced Level Third Edition, pg 441). The water potential of a cell is the overall tendency for water to diffuse into the cell by osmosis. There are two factors that affect the water potential of a plant cell, which are solute potential and pressure potential. Water potential can be calculated by using the formula below:- Ψ cell = ψs + ψp Solute potential in the plant cell is the amount that the solute molecules in its cell sap lower than the water potential of the solution. The value of the solute potential is always negative as the solute molecules always make the water potential in the cell lower. The more the concentration of solute molecules in the vacuole of a plant cell, the more negative the water potential. (Source by: Nelson…show more content…
This was because distilled water has the highest water potential which is zero. As water moved from higher water potential to lower water potential, therefore the water diffused into the cell by osmosis. The cell solution was diluted and the volume of the cell increased. This explains why the mass of the potato discs increased. The pressure potential had developed as the cytoplasm was pushed against the cell wall. While the 0.2 moldm-3 sucrose solution contained more solute molecule, thus slightly decrease the water potential. Therefore the percentage change in mass was lower than the distilled

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