BIOMOLECULES AND ENZYMES

Detailed explanation-1: -If the solution contains starch, the iodine turns into blue/black color. The positive iodine result indicates the presence of starch, in which the color gets changed from violet to black. The negative iodine result indicates the absence of starch in a solution, which shows yellow color.

Detailed explanation-2: -A positive result for the iodine test (starch is present) was a colour change ranging from violet to black; a negative result (no starch) was the yellow colour of the iodine solution.

Detailed explanation-3: -Pure iodine is violet, but when it’s dissolved in water, it accepts an electron from the oxygen atom, affecting how it absorbs light. When you shake the fluids, the iodine leaves the water and dissolves in the oil, and returns to its purple colour!

Detailed explanation-4: -Two drops of iodine/potassium iodide solution and one ml of water are added. Solids may be tested by placing the iodine/potassium solution directly on the solid. A positive test is indicated by: the formation of a blue-black complex.

Detailed explanation-5: -Starch Test: Add Iodine-KI reagent to a solution or directly on a potato or other materials such as bread, crackers, or flour. A blue-black color results if starch is present. If starch amylose is not present, then the color will stay orange or yellow.