starch test問題~~~help

Starch is a polysaccharide. Unlike simple sugars such as glucose, starch is insoluble in cold water. Heating is required to prepare a starch solution. Iodine combines with starch to form a blue-black complex molecule. Thus the appearance of a blue-black colour after addition of iodine solution indicates the presence of starch.

即係話你見到ge dark blue 色ge 野只係 starch+iodine 做成 ge reaction. 而個reactant 就係上面講ge "complex molecule" ~