In the following experiment we had to create a cell membrane using a dialysis bag. We tied one end of the bag with a piece of string and opened the other end to place 15% of glucose and 1% of starch. Once we got that in bag we tied off the other end. While I was working on the bag my partner was working on the cup. She had to get a plastic 8-oz cup and fill it with 4 mL of IKI ( iodine solution). She also had to fill it up with distilled water. Then she mixed it well to make a brown color. She tested the cup with a Urine Reagent Strip, a strip to test a person's glucose levels, to make sure no glucose was in the water. Then we both recorded the color and the glucose levels on a sheet of paper. After recording the color we then place our glucose dialysis bag into the water. We left it on the counter and waited about 30 minutes then took a look at it again. The diffusion already started to happen. The water and IKI was starting to turn light brown. The glucose and starch inside were starting to turn a black color. We tested it again with another strip and both tested positive for glucose.
We left for the weekend and then came back today to see the final results. When we went to look at the cup a lot of changes occurred. On a sheet of paper we had to answer analysis of results questions. Here are the questions:
1) A)How would you explain the results you obtained?
Over the weekend our glucose and iodine (IKI) experiment had a drastic change. The iodine turned from a brown color to transparent. The glucose and starch membrane turned to a purple, blackish color.
B) Which substance(s) are entering the bag and which are leaving the bag? Support your answer with experimental evidence.
The iodine and distilled water entered the membrane because it started out as a brown color and is now transparent. The glucose and starch were leaving because it started out white and turned a blackish purple color. We also tested the water for glucose and there was a count of 100/5 mg in the water.
2) What evidence could have been collected to show quantitatively that water diffused into the dialysis bag? The color and glucose levels of the experiment show that the water diffused into the membrane, (dialysis bag).
3) What results would you expect if the experiment started with a glucose and IKI (iodine) solution inside the bag and only starch and water outside? Why?
We think that the IKI solution would not diffuse as well because of the starch and water on the outside of the dialysis bag.
Picture Websites
No comments:
Post a Comment