Using what you learned in the virtual lab activity, determine the results of the tests in the picture. Below is the Biuret test used to test for proteins. Controls Test Results Biuret test Controls: blue tube is negative and purple tube is positive Biuret Test Results: Tube A light blue, tube B light purple, tube C clear and tube D dark purple 1. What is the result of tube A? 2. What is the result of tube B? 3. What is the result of tube C? 4. What is the result of tube D? 5. Of the four test results shown, which tube (A-D) shows the greatest concentration of protein?