Testing for Macromolecules

Describe the positive test for starch. Explain how you know. The positive test for starch is adding iodine solution. In the experiment, the starch solution had the most dramatic reaction with the iodine solution. It turned to an opaque bluish-purple solution while other samples all turned to a colour related to orange and yellow other than the vegetable oil. But the vegetable oil was more translucent than completely opaque.

Describe the positive test for glucose. Explain how you know. The positive test for glucose is be adding Benedict’s solution. In the experiment, the glucose solution had the most dramatic reaction with the Benedict’s solution after it got heated. It turned to an opaque yellowish orange solution with dark-orange precipitate at the bottom while other samples all turned to a colour related to blue, other than the unknown solution.

Describe the positive test for lipid. Explain how you know. The positive test for lipid is the Sudan IV solution. I know this because it is the only substance who turned shiny afterwards. All of the other ones were matte.

Describe the positive test for protein. Explain how you know. The positive test for protein is adding the Biuret solution. I know this because the protein is the substance who had the most dramatic reaction with the Biuret Solution. While all of the other substances turned blue and yellow, the protein turned purple.

What substances were present in the unknown solution? Explain how you know. The glucose solutions and starch solutions are the ones included in the unknown solution. I know this because they have the same positive tests.

What was the the purpose of testing distilled water for each part of the investigation. The purpose of testing distilled water for each part of the investigation was to show the most natural reaction and colour change with the indicators without any other chemicals affecting the results since distilled water is a pure substance with nothing mixed in it.

Suppose you have a sample of a sports drink that may contain one, two, three or all four of the macromolecules you tested in the investigation. Write a procedure describing how you would test the sample to determine which macromolecules it contains. In order to test the sample to determine which the macromolecules it contains, I would take a little bit of the sample and put it in a test tube, and add a few drops of Benedict’s Solution and heat it. Then look at the reaction and compare it to the ones of starch, glucose, lip and protein solutions. Then I’d repeat my first step with Iodine Solution, Sudan IV solution and Biuret solutions; without heating though. Finally, I’d compare those results to the ones I got while testing the macromolecules.