A clear solution is mixed with Biurets reagent and the resul

A clear solution is mixed with Biuret\'s reagent and the resulting solution is blue. What do you know for sure about this solution in regards to what molecules are present/absent ? When exposed to iodine, what happened to the potato? What happened to the onion? Why did these color changes (or lack thereof) occur? Be sure to relate this to the functions of each plant structure .

Solution

4. The biuret test also called as Piotrowski\'s test. It is a chemical test used for detecting the presence of peptide bonds (Bonds between amino acids are called peptide bonds). In the presence of peptides, a copper(II) ion forms violet Blue-colored coordination complexes in an alkaline solution.

This colour less solution gives blue colour with biuret reagent indicates the presence of peptide bonds. Which indcates the colour less solution have a soluble proteins.

5. Idone gives dark blue colour when reacts with starch. Potatos stores food material in the form of starch. When It reacts with iodine it gives blue colour, where as in onions as the absence of starch it gives negative result.