While testing for biological macromolecules in an unknown, you find that it reacts strongly with iodine and the solution immediately turns a very dark black. The macromolecule at hand must be:.

Carbonhydrate (Starch)

Explanation:starch is a polysaccharide ,made up of glucose monomers.starch is an insoluble carbonhydrate.it forms a main storage material for green plants.starch is a made up of two fractions namely; Amylose and amylopectin.

They both contain alpha 1,4 glycosidic linkages but amylopectin also contains branches of alpha 1,6 glycosidic linkages.

Starch gives a blue-black colouration with iodine.This is due to it's reaction with amylose.its structure is helically coiled and hence can trap iodine molecules.

This blue black colour changes on heating because amylose loses its structure on heating

c

explanation: