Question

Dialysis bags can be used as models of cells to explore the movement of materials into and out of cells. Students set up an investigation with a dialysis bag containing a 2% iodine solution in a beaker containing a 9% starch solution as shown in the figure. Starch turns blue-black in the presence of iodine. The dialysis bag is permeable to water and iodine but not to starch.Which two observations most accurately predict what will occur in the investigation?(4 points)ResponsesThe concentration of starch in the dialysis bag will increase.The concentration of starch in the dialysis bag will increase.The mass of the dialysis bag will increase.The mass of the dialysis bag will increase.The solution in the dialysis bag will turn blue-black.The solution in the dialysis bag will turn blue-black.The mass of the dialysis bag will decrease.The mass of the dialysis bag will decrease.The solution in the beaker will turn blue-black.

Answer 1

In the described investigation with the dialysis bag, the following two observations most accurately predict what will occur:

1. The mass of the dialysis bag will increase. (Water will move into the bag via osmosis, increasing its mass.)
2. The solution in the dialysis bag will turn blue-black. (Iodine from the beaker will diffuse into the dialysis bag and react with the starch, turning it blue-black.)

These two observations correspond to the movement of materials due to osmotic pressure and diffusion. The starch is contained within the dialysis bag, while both iodine and water can move freely across the membrane.