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

The 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.

Answer 1

In this investigation, the dialysis bag contains a 2% iodine solution and is placed in a beaker with a 9% starch solution. Considering the permeability of the dialysis bag and the properties of the substances involved, we can predict the following observations:

1. The solution in the beaker will turn blue-black. - This is because iodine from the dialysis bag is able to diffuse into the beaker and react with the starch, causing the blue-black color change.

2. The mass of the dialysis bag will increase. - This will occur due to water moving into the dialysis bag through osmosis (since the concentration of solutes is higher in the beaker), resulting in an increase in mass.

So the two observations that most accurately predict what will occur in the investigation are:

• The solution in the beaker will turn blue-black.
• The mass of the dialysis bag will increase.