Which macromolecules were present in the unknown solution? in the milk?

These macromolecules might either be amino acids, proteins or nucleic acids. They are accountable for the chemical changes and reactions that moves largely the cell and its composition. Take for example the cytoplasm of the cell where these organelles are settled. These simple organelles are composed of macromolecules which ignites and catalysis different functions that enables cells, in macro-perspective in motion and metabolism. In intestines for instance, metabolism occurs and breaking down parts of a food to simpler compounds that are used and these nutrients delivered throughout the body and again broken down by into smaller components. 

sorry to break it to ya but no one can answer your question it's just

jk but i am serious about the part that most people cant answer it beacuse you did not mention the section you are talking about. but it would if you added some detail and were a bit more specific.