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Bio Lab

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1. The solute that passed through the selectively permeable membrane moving out of the cell (dialysis tubing) was glucose. The evidence of this conclusion was the colour of the glucose test strip. The test strip initially showed no presence of glucose in the solution in the cup, but after leaving the dialysis tubing within the iodine solution over a period of two days the test strip showed a presence of glucose within the solution. Glucose is a small enough molecule to pass through the selectively permeable membrane by following the concentration gradient. The starch molecules remained within the dialysis tube. This conclusion was drawn due to the fluid within the dialysis tubing turning a blue/black colour, a characteristic of iodine in the presence of a starch. Also, starch is a polysaccharide and is too large of a molecule to pass through the selectively permeable membrane.

2. In Part 1, as glucose was passing out of the "cell", iodine molecules was passing into the "cell". This conclusion was drawn due to a black/blue colour being in concentration in the bag when the iodine was only added to the water in the cup, not the dialysis tubing directly.

3. The "cell" in Par 1 was in a hypotonic environment. The solute, glucose, was in a higher concentration within the "cell" than outside the "cell" thus causing water (as well as the iodine) to enter the dialysis tube. This was proved by the fact that the dialysis tube became firmer than it was initially, due to the fact that water entered the cell increasing the density of the "cell" and creating a isotonic environment.



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