To demonstrate how diffusion works in a cell, we did an experiment with iodine and starch. In the experiment, we put a spoonful of starch and a small amount of water into a plastic baggie. Then, we filled a beaker halfway up with water. Lastly, we poured some iodine into the beaker and placed the starch baggie into the beaker. To finish the experiment, we had to let the baggie sit in the beaker for at least fifteen minutes. After fifteen minutes, the starch in the bag was supposed to turn purple. This is because of diffusion. Diffusion is the term used to describe the process of molecules moving form an area of high concentration to an area of low concentration. In the lab, the plastic baggie was selectively permeable. Selectively permeable means that only certain things can go in and out. Since the plastic baggie was selectively permeable, the iodine molecules were able to go through the bag and spread into the starch. Once starch and iodine mix, they become purple. This is supposed to happen. However, in our lab the iodine molecules were not small enough to go through the baggie.
This experiment is a demonstration of what happens to cells. The plastic baggie represents the cell membrane. The starch represents the cell and the iodine represents things outside the cell. Our cell membrane is selectively permeable. This way only certain things can go into and out of the cell. For example, the cell allows water to come in and allows waste product to go out. However, it doesn't allow the organelles to go out or waste to come in.
Picture Source:
No comments:
Post a Comment