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.

Question

Which two observations most accurately predict what will occur in the investigation?

(4 points)
Responses

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 increase.
The mass of the dialysis bag will increase.

The mass of the dialysis bag will decrease.
The mass of the dialysis bag will decrease.

The concentration of starch in the dialysis bag will increase.
The concentration of starch in the dialysis bag will increase.

The solution in the beaker will turn blue-black.
The solution in the beaker will turn blue-blac…

Answer 1

In this investigation with the dialysis bag and the solutions involved, the following two observations most accurately predict what will occur:

1. The solution in the dialysis bag will turn blue-black. - This happens because iodine can diffuse into the dialysis bag, where it will react with the starch present in the beaker, leading to a blue-black color change.

2. The mass of the dialysis bag will increase. - This is expected because water will move into the dialysis bag from the beaker, where the higher concentration of starch is located, leading to an overall increase in mass within the bag.

Therefore, the correct predictions are the first and second statements.