How can you detect starch in plant tissues?

The detection of starch in plant tissues is most commonly conducted using iodine solution, which reacts specifically with starch. When iodine solution, which is initially brown, comes into contact with starch, it undergoes a significant color change, turning a distinctive blue-black color. This reaction indicates the presence of starch because the iodine interacts with the helical structure of the starch, forming a starch-iodine complex that is blue-black.

In contrast, starch being colorless in solution is not relevant, as it doesn’t provide any indication of its presence. Bubbles in water would typically indicate a gas release, which is not associated with starch detection. The statement regarding starch dissolving completely in water is also inaccurate; starch does not dissolve entirely in cold water, and in fact, its insolubility is a key factor allowing the iodine test to be effective. Thus, the blue-black color change provided by the iodine is the definitive method to confirm the presence of starch in the plant tissue.