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Cell Membranes

            Movement of Sucrose Across Plant Cell Membranes.
             The cell membrane is a barrier between the internal and external environments of a cell. Water molecules are the sole molecules that can freely move across the cell membrane. This process is known as osmosis, and it is stated as being the net movement of water across a cell membrane. For this study, we obtained potato tubers and immersed them in different solutions of sucrose concentrated water. The purpose of this study was to determine the osmotic concentration of potato tuber cells by their change in mass. .
             (Ha:) It was hypothesized that the final mass of the potatoes immersed in the solution of sucrose would change, due to the net movement of water. We also hypothesized that the mass of the potatoes immersed in the distilled water containing no sucrose would be greater. We came to this hypothesis by making reference to the fact that the sucrose within the potatoes would be greater than that of the water. Thus, the water would attempt to pass through the cell membrane to equal the external environment with the internal environment of the potatoes. This process would be reversed (water leaving the cell, due to higher concentration of sucrose outside the cell) as the concentration of sucrose became greater. (Ho:) If there were to be no effect on the cells of the potatoes, our hypothesis was that there would be no change in the mass of the potato because the solution, as well as the potato would be in an isotonic environment.
             Materials and Methods:.
             Six potato tubers were obtained, each cut to 4 cm. All six cylinders were placed on a moistened paper towel, and each was removed to be thinly sliced with a razor blade. Each sliced potato tuber was rinsed and blotted dry, then placed in an empty weight boat to be weighed on the balance. The balance was tared before each tuber was weighed. After each tuber was weighed, the mass was recorded on a chart.