Diffusion & Osmosis Day 2

In the second day of the Osmosis and Diffusion lab, the experiments shifted towards diffusion. The purpose of the lab was to test the diffusion variation of glucose vs. starch. Using the special tubing Mr. Quick provided, we made a cell that was 15% glucose and 1% starch and submerged it under water. After waiting a period of time, we used indicators to determine the results of the lab. 

The most important indicator was the iodine. Iodine, in the liquid form, is used to test for the presence of starch. After adding it into the cub, the iodine indicated starch within the cell, but not within the water itself. This meant the starch, being a very large macromolecule, was not able to diffuse out of the cell. 

After confirming the lack of starch in the water, our group began testing for the presence of glucose. We used benedict's as an indicator for it. We added a small amount into the water sample and placed it into a hot water bath. The solution went from a light sky blue to a musty orange, a positive test for glucose.

 

These results demonstrated how size is a factor when diffusion occurs in cells. The smaller glucose was able to diffuse out into the water, whereas the large starch could not.


After this, we did another diffusion lab using cell blocks. We poured sodium hydroxide into 3 different beakers and placed the blocks into the solution. Since the solution was a bright pink color, we were able to see how much of the solution had entered the block in the amount of time it was left to sit.

The "cells" were then cut open and measured to see the amount of diffusion that occurred. Throughout the cells, they appeared to have the same amount diffuse into them. However, within the smaller cell bock, it appeared as if the solution had gone completely through. In the larger cells, there was a same amount of diffusion, but because of the large size, it had only affected a small percentage of the cell.