From my background knowledge I predict that as the concentration of the sucrose solution that the potato cylinder is placed in increases, the size and weight of the potato cylinder will decrease over the period of 48hours, and vice versa, if sucrose solution concentration decreases, the potato cylinder should swell up and its size and weigh will increase. These predictions have scientific explanations. When a potato cylinder is placed in a high concentration sucrose solution where little water or no water at all is added, the potato cells under go a process called plasmolysis.Plant cells, in this case potato cells have a thick cell wall which is freely permeable and supports the cell; inside this cell wall is the protoplast which has a partially permeable plasma membrane.
When the concentration of the surrounding solution in this case sucrose solution is high, it means that the solution potential surrounding the cell has very low water potential compared to the potato cell.So osmosis takes place, this is the movement of water molecules from a high potential region to a lower potential region, so water leaves the potato cell by osmosis. As it does so, the protoplast gradually shrinks until it is exerting no pressure at all on the cell wall. At this point the pressure potential is zero, which means that the water potential of the cell is equal to the water potential in the solution.
The shrinking process pulls away the protoplast from the cell wall and this is called plasmolysis, in other words the cell is plasmolysed. When water is lost, cells shrink in size and lose weigh due to lose of water, so this means that potato cylinder will decrease in size and weight from its original state. But when the potato cylinder is placed in pure water which has the highest water potential of zero or any other solution which has higher water potential than the potato cells, the potato cells will swell up, therefore their size and weight increases.This is again due to osmosis but in the opposite direction.
Now the solute has higher water potential, the water molecules enter the potato cells through the freely permeable cell wall and the partially permeable plasma membrane and enter the protoplast. This increases the volume of the cell, the protoplast (the living part of the cell inside the cell wall) starts to push against the cell wall and pressure starts to build up rapidly.This is the pressure potential and it increases the water potential of the cell until water potential inside the cell equals the water potential outside the cell, and equilibrium is reached. The inelastic and tough cell wall prevents the cell from bursting.
When the potato cell is fully inflated with water, it is described as turgid. So the potato cylinder is now larger in size and has increased weight due to the extra water in its cells.
