A student filled a bag of dialysis tubing with a milky-white starch solution and placed the bag in a beaker of iodine- water solution as shown in the diagram below. An hour later, the student observed that the starch solution had turned blue-black (positive test for starch). What is the most probable explanation for the change?

The iodine diffused into the bag.

Explanation:

carbohydrates: (starches and sugars) composed of carbon, hydrogen, and oxygen.

lipids: (fats, oils, and waxes) are made of carbon and hydrogen atoms.

nucleic acids: contain hydrogen, oxygen, nitrogen, carbon, and phosphorus. they are polymers of nucleotides. a nucleotide has three parts, a 5-carbon sugar, a phosphate     (-po⬇️4) group, and a nitrogenous base.

proteins: made up of nitrogen, carbon, hydrogen, and oxygen. they are polymers of amino acids.