Compare the circulatory system of a plant and animal

In plants, there is a conducting tissue that is located in the veins. Inside, there are xylem cells that conduct water and minerals upward from roots to leaves and phloem that conducts food. Plants have only water solutions flowing through the tubing. Animals can have one of two kinds of circulatory systems: open or closed. In animals, each blood vessel in the network is responsible for transporting nutrients and oxygen to cells and for removing wastes and carbon dioxide from cells. 

The answer is joseph is observing the colour of the reaction mixture to see whether proteins are present in the given solution.