Partial preview of the text
Download Lab 6: Testing for Nutrients and more Lab Reports Biology in PDF only on Docsity!
Name Testing for Nutrients Background Substances in food that can be used by an organism for energy or for growth and repair are called nutrients. Nutrients include carbohy- drates, proteins, fats, minerals, and vitamins. Cells of all organisms are composed of these nutrients and water. There are several chemical tests that can be used to determine which nutrients, if any, are present in a substance. You will use some of these tests in this activity. Objectives In this activity you will: lL. Learn how to test substances for the presence of carbohydrates, proteins, and fats. 2. Perform nutrient tests on several foods to determine which nutri- ents are present. Materials Pyrex test tubes scalpel or single edge razor blade test tube rack plastic funne) test tube holder glass-marking pencil 10-mL graduated cylinders paper towels glass stirring rods boiling-water bath hot plate pipettes 5% glucose solution dry cornstarch Benedict's solution Lugal's salution in dropper bottle ege albumen solution salad oil biuret reagent in dropper bottle squares of unglazed brown paper pieces of potato, bread, carrot, beakers onion, walnut, apple, and ruler cheese water Procedures and Observations a & PART |. TESTING FOR CARBOHYDRATES Starches and sugars belong to the group of organic compounds called carbohydrates. Starch molecules are composed of many simple sugar molecules Jinked together. Starch molecules and simple sugar molecules have different chemical behaviors. For this reason, different chemical reagenis, or testing agents, are used to test for starch and for simple sugars. A solution of iodine, Lugol's iodine solution, is the reagent used to test for the presence of starch. Lugol's solution is yellow-brown, However, It reacts chemically with starch to form a blue-black substance called jodide of starch. 31 
