You are given four test tubes containing purified biological macromolecules. The test tubes are unlabeled except that each is labeled with a number between 1 and 4. You are told that one test tube contains amylase (a protein), one contains vegetable oil (a lipid), one contains starch (a carbohydrate), and one contains DNA (a nucleic acid). You then perform some tests on the macromolecules and collect the following information: 1.) Test tubes #2 and #4 contain nitrogen, but the other tubes do not. 2) The contents of test tube #3 are not soluble in water, but the contents of the other test tubes are soluble in water. 3) The contents of test tube #1 can be broken down into subunits that are all exactly identical to each other. 4) The macromolecule in test tube #2 is found to have a globular shape and reacts with Biuret reagent. 5) The macromolecule in test tube #4 contains the nitrogenous bases Adenine, Thymine, Guanine, and Cytosine. What are the identities of the macromolecules present in the four test tubes? Justify your choices using the collected data.