Question

what can you conclude about the diffusion of iodine, glucose, and starch across the selectively permeable dialysis tubing membrane?
a. diffusion occurred with iodine and glucose because their molecular movement is less than that of starch.
b. diffusion occurred based on molecular size. iodine and glucose are much smaller molecules than starch; therefore, they were able to diffuse
c. diffusion occurred with iodine and glucose because the dialysis tubing membrane contained channels for those molecules.

Explanation:

To determine the correct conclusion about diffusion across the dialysis tubing membrane, we analyze each option:

• Option A: The reasoning about "molecular movement" being less is incorrect. Diffusion through a selectively permeable membrane (like dialysis tubing) is primarily based on molecular size, not the rate of molecular movement in general. So A is wrong.
• Option B: Dialysis tubing is selectively permeable, allowing small molecules to pass through and restricting large ones. Iodine (a small ion/molecule) and glucose (a monosaccharide, small molecule) are much smaller than starch (a polysaccharide, large molecule). So diffusion occurs based on molecular size, with smaller molecules (iodine, glucose) diffusing and starch not. This matches the principles of diffusion across selectively permeable membranes.
• Option C: Dialysis tubing is a simple selectively permeable membrane based on pore size (molecular size exclusion), not on having specific channels for iodine and glucose (channels are more associated with cell membranes with proteins, not simple dialysis tubing). So C is incorrect.

Answer:

B. Diffusion occurred based on molecular size. Iodine and glucose are much smaller molecules than starch; therefore, they were able to diffuse