in a potato transport experiment, students placed a starch - solution in a dialysis tubing and then tied it…

in a potato transport experiment, students placed a starch - solution in a dialysis tubing and then tied it shut using a fishing line. dialysis tubing does not allow starch to pass through it. the dialysis tubing bag was then submerged in a beaker filled with water and iodine. the image on the left shows before it was submerged and the image on the right shows how the dialysis tubing looked after it had been sitting in the beaker overnight. five students were asked to use their knowledge of cell membranes and diffusion to explain what happened in the experiment. which students explanation do you agree with the most and why? dylan: this is an example of osmosis, but more specifically, hypertonic. the water had a greater concentration of solute compared to the starch. in order to balance the molecules, water left the cells which caused the change in color. it changed colors because the iodine interacts with the starch to make that dark purple color. sophie: the iodine traveled through the tubing due to passive transport. it moved from a high concentration in the cup to a low concentration inside the tubing. the tubing had a very low concentration of iodine, while the cup had a very high concentration. the tubing acted as the cell membrane. greg: in the experiment, the dialysis tubing acted as a semipermeable membrane similar to the ones in cells. the tubing allowed the iodine and the water to diffuse through it, and therefore the iodine turned the solution purple, due to the presence of the starch in the solution. osmosis occurred as well, because the high concentration of the starch in the tubing led to the water - iodine solution to diffuse towards the starch, but the water - iodine solution still stayed yellow because the dialysis tubing being semi - permeable, did not allow the starch to diffuse towards the water - iodine solution. alice: iodine tests for starch and black shows positive. the cell membrane of the tubing is semi - permeable. because it is semi - permeable, it lets some of the iodine molecules in to try to maintain homeostasis and make the particles balanced, a process also called diffusion. the iodine came into the tubing with the starch to try to balance the experiment and turned the starch black. thomas: the tube didnt let out the starch into the water and it acted as a membrane. i know this because only the bag turned blue in the experiment. since the starch solution turned blue/purple it must have let the iodine in. the iodine moved from an area of high concentration in the cup to an area of low concentration in the tube. the water didnt move so its not osmosis.

in a potato transport experiment, students placed a starch - solution in a dialysis tubing and then tied it shut using a fishing line. dialysis tubing does not allow starch to pass through it. the dialysis tubing bag was then submerged in a beaker filled with water and iodine. the image on the left shows before it was submerged and the image on the right shows how the dialysis tubing looked after it had been sitting in the beaker overnight. five students were asked to use their knowledge of cell membranes and diffusion to explain what happened in the experiment. which students explanation do you agree with the most and why? dylan: this is an example of osmosis, but more specifically, hypertonic. the water had a greater concentration of solute compared to the starch. in order to balance the molecules, water left the cells which caused the change in color. it changed colors because the iodine interacts with the starch to make that dark purple color. sophie: the iodine traveled through the tubing due to passive transport. it moved from a high concentration in the cup to a low concentration inside the tubing. the tubing had a very low concentration of iodine, while the cup had a very high concentration. the tubing acted as the cell membrane. greg: in the experiment, the dialysis tubing acted as a semipermeable membrane similar to the ones in cells. the tubing allowed the iodine and the water to diffuse through it, and therefore the iodine turned the solution purple, due to the presence of the starch in the solution. osmosis occurred as well, because the high concentration of the starch in the tubing led to the water - iodine solution to diffuse towards the starch, but the water - iodine solution still stayed yellow because the dialysis tubing being semi - permeable, did not allow the starch to diffuse towards the water - iodine solution. alice: iodine tests for starch and black shows positive. the cell membrane of the tubing is semi - permeable. because it is semi - permeable, it lets some of the iodine molecules in to try to maintain homeostasis and make the particles balanced, a process also called diffusion. the iodine came into the tubing with the starch to try to balance the experiment and turned the starch black. thomas: the tube didnt let out the starch into the water and it acted as a membrane. i know this because only the bag turned blue in the experiment. since the starch solution turned blue/purple it must have let the iodine in. the iodine moved from an area of high concentration in the cup to an area of low concentration in the tube. the water didnt move so its not osmosis.

Answer

Brief Explanations:

The dialysis tubing acts as a semi - permeable membrane like a cell membrane. Iodine can pass through it due to diffusion (from high to low concentration) and react with starch inside the tubing to change color. Osmosis is the movement of water across a semi - permeable membrane, and in this case, water movement is not the main focus. Sophie, Alice, and Thomas correctly describe the passive transport of iodine through the semi - permeable tubing and the reaction with starch. Dylan misidentifies the tonicity situation, and Greg has some inaccuracies in his description of osmosis and diffusion relationships.

Answer:

Sophie, Alice, Thomas' explanations are more accurate as they correctly describe the diffusion of iodine through the semi - permeable membrane and the iodine - starch reaction.