Formal Scientific Lab Report
The objectives of this lab was to be able to create models of cells with the dialysis tubing to show us how the plasma membrane is selectively permeable, to study the effects of osmosis on a model cell, and to foresee the effect of solute concentration on osmosis. In order to achieve these objectives, we had to fill the dialysis tubing with either water, or different amounts of sucrose. We then tied off the tubes and put them into beakers of distilled water to see how the color changed in the bag/beaker. The result was that the more sucrose in the bag, the greater the final mass.
The reasons for doing this lab are so that we can learn about osmosis with a model similar to a cell and so that we can have a better understanding of the process and nature of osmosis. Osmosis is diffusion but with water molecules. A concentration gradient exists and because of this, diffusion of solutes can’t happen. Very select things can pass in and out, such as water, oxygen, and carbon dioxide. In this situation, a large molecule of starch would be dissolved in water because the molecule is too big to fit through the membranes pores. Since the membrane in permeable to water molecules, it causes the water molecules to diffuse from an area of high water concentration to an area of low water concentration. This movement itself is osmosis. To determine if the concentration of solutions is isotonic (solute is equal to the cell), hypotonic (solute is lower outside of the cell), or hypertonic (solute is higher outside of the cell), you measure the total amount of particles in the solution. My hypothesis is: if the dialysis tubing that is filled with sucrose solution and fully emerged in a beaker of distilled water, then the water will seep into the dialysis tubing and the tubing will become a greater mass. The independent variables in this lab are the beakers of distilled water, and the...
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