Investigating the Water Potential of Potato Cells
Investigating the Water Potential Of Potato Cells Aims 1. To test how water potential, in a solution, affects the movement of water in and out of a cell by osmosis Prediction I predict that by increasing the water potential around the outside of the potato cell, (i.e. so that the water potential is greater outside the cell compared to the inside of the cell e.g. 0m sucrose) that the net movement of water into the cell will increase. This is due to the water potential being greater outside the cell compared to the inside of the cell, therefore water will diffuse into the cell by a process of osmosis. The opposite however will occur when the water potential outside the cell is lower than that inside the cell (i.e. with hypotonic solutions, such as a solution with a sucrose concentration of 1m and 0.75m). This is due to the water potential outside the cell being less than that inside the cell and therefore water moves out of the cell by osmosis. With a larger water potential gradient, more particles will move in order to balance the water potential in the cell and outside the cell, hence more water will move into the cell in a 0m solution of sucrose, compared to a 0.25m solution. There maybe a situation where the water potential is the same both outside and inside the cell (i.e. the solution is isotonic) hence there will be no net movement of water into the cell.
“Osmosis is the movement of water molecules from a region of high water concentration to a low water concentration through a semi-permeable membrane. Our aim is to investigate the water potential of a potato through osmosis, by finding the difference in weight before and after the potato has been set in a solution of water, sugar or salt.” Variables To Control There are several variables to control including volume of water. Firstly the volume of water needs to be kept constant to allow a fair test amongst all the potato strips because different amounts of water will determine how much of it will
Method 1.
“Osmosis is the movement of water molecules from a region of high water concentration to a low water concentration through a semi-permeable membrane. Our aim is to investigate the water potential of a potato through osmosis, by finding the difference in weight before and after the potato has been set in a solution of water, sugar or salt.” Variables To Control There are several variables to control including volume of water. Firstly the volume of water needs to be kept constant to allow a fair test amongst all the potato strips because different amounts of water will determine how much of it will
Method 1.