BIOMOLECULES AND ENZYMES

Detailed explanation-1: -Iodine is a common indicator to test for the presence of starch. The light orange-brown colour Iodine solution turns blue-black in colour when it reacts with starch. This indicates the presence of carbohydrates in the food item to which iodine solution was added.

Detailed explanation-2: -Amylose present in starch is the reason for change in its colour to blue black. Iodine is not soluble in water so it is dissolved along with potassium iodide that forms a triiodide molecule which enters the helical structure of amylose and changes the colour of starch.

Detailed explanation-3: -Iodine produces a blue-black colour on reacting with starch. Starch is a complex carbohydrate found in a wide range of food, including potatoes and whole grains.

Detailed explanation-4: -Using iodine to test for the presence of starch is a common experiment. A solution of iodine (I2) and potassium iodide (KI) in water has a light orange-brown color. If it is added to a sample that contains starch, such as the bread pictured above, the color changes to a deep blue.

Detailed explanation-5: -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.