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A basic understanding of diffusion and osmosis

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Abstract: The purpose of this lab was to have a basic understanding about concepts diffusion and osmosis. In this lab we had dialysis tube as a cell membrane of cell, which lets small particles pass through it and we had test tube as tightly joined surface, which doesn't let any particles pass through it. As a result we saw that small particles like glucose and iodine diffused through dialysis tube, but large particle like starch couldn't diffuse dialysis tube. From this lab it can be concluded that small particles like glucose and iodine can pass through phospholipid's double layer of cell membrane to provide nutrition to cell, but larger particles like starch needs to go through the entrance of cell. Introduction: Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. Osmosis is the diffusion of water molecules across a selectively permeable membrane. The purpose of this lab is to identify the particles that can diffuse through dialysis tube. I hypothesized that starch and glucose can diffuse through the dialysis tube. ...read more.


The dialysis tubing acted as a semi permeable membrane by allowing small particles to diffuse. Discussion: The use of dialysis can make it very easy for use to understand diffusion and osmosis in cell membrane. In this lab we discovered the particle that can or can't pass through the cell membrane. In our lab we had dilute Lugol's solution in beaker and in two dialysis tubes we had glucose solution and starch suspension. While we were doing the lab we found out that iodine has moved from dilute Lugol's solution in the beaker into the dialysis tube. We know that dilute Lugol's solution is made up of iodine and water. Scientifically when starch reacts with iodine the solution turns little black. So this statement is enough to prove that iodine has diffused into dialysis tube from the beaker. But we also had starch in test tube, then why didn't that change its color? Now we come across to the prediction that small particles can pass through dialysis tube and not the test tube. ...read more.


We also know that glucose left dialysis tube and mixed with beaker's solution. That's why it shows that neither glucose nor iodine is largest. So the presence of starch in dialysis tube proves that starch is the largest particle here. Sources of Experimental Error. Since this experiment was done by a human and not by a robot it was usual that there should be a source of error. While we were doing this lab we faced some problems that affected our experiment. We had some minor problems that didn't do much bad, but our major problem wasted our time, which we lacked. In this lab we had to tie two ends of dialysis tube tightly, but by mistake there was a lose point in our dialysis tube of starch. This leaking of starch was ruining beaker's solution and as well as our solution, which made lab worth no use. So to have a good lab we had to everything again which wasted a lot of time, but still we covered it all and got it all right. The other problems like usage of contaminated solution and amount didn't matter a lot, so it was fine. But, as a result our lab was a great success. ...read more.

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