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Name:__________________________________ Date:_____________ P#:___ Lab: Corn Into Milk (Page 55-58 or Unit 1: L.E. 6) 1. Place your data (+/-) in the table below and then transfer that data to the class table. Substance Corn Benedicts Biuret Iodine Oil Milk 2. Refer to your nutrient gizmo packet for determining positive and negative results. Activity A. Questions 1-4. A. Benedict's reagent is used in a test (Benedict's test) commonly used for the presence of reducing sugar(s), however other reducing substances also give a positive reaction. This includes all monosaccharides and many disaccharides, including lactose and maltose. B. The Biuret reaction can be used to assess the concentration of proteins because peptide bonds occur with the same frequency per amino acid in the peptide. The intensity of the color, and hence the absorption at 540 nm, is directly proportional to the protein concentration. C. The Iodine test is used to test for the presence of starch. Iodine solution — iodine dissolved in an aqueous solution of potassium iodide — reacts with the starch, producing a purple-black color. D. Paper test is a confirmatory test for fats and oils. Here, oil or melted fat is dropped on a piece of paper to form a translucent grease spot. 3. Digestion and nutrients: When we eat such things as bread, meat, and vegetables, they are not in a form that the body can use as nourishment. Our food and drink must be changed into smaller molecules of nutrients before they can be absorbed into the blood and carried to cells throughout the body. Digestion is the process by which food and drink are broken down into their smallest parts so that the body can use them to build and nourish cells and to provide energy. The digestive system is a series of hollow organs joined in a long, twisting tube from the mouth to the anus. Inside this tube is a lining called the mucosa. In the mouth, stomach, and small intestine, the mucosa contains tiny glands that produce juices to help digest food. Digestion involves the mixing of food, its movement through the digestive tract, and chemical breakdown of the large molecules of food into smaller molecules. Digestion begins in the mouth, when we chew and swallow, and is completed in the small intestine. The chemical process varies somewhat for different kinds of food. 4. Movement of Food Through the System: • Mouth: Seconds • Esophagus: Seconds • Stomach: Up to 3 ½ Hours • Small Intestine: Minutes • Large Intestine: Hours In the mouth, carbohydrates are broken down by amylase into maltose (disaccharide) and then move down the esophagus, which produces mucous for lubrication, but no digestive enzymes. In the duodenum, disaccharides are broken down into monosaccharides by enzymes called maltases, sucrases, and lactases; the monosaccharides produced are then absorbed into the bloodstream and transported to cells to be used in metabolic pathways to harness energy. In the stomach, proteins are broken down into peptides, which are then broken down into single amino acids that are absorbed in the bloodstream though the small intestine. Lipids are digested mainly in the small intestine by bile salts through the process of emulsification, which allows lipases to divide lipids into fatty acids and monoglycerides. Monoglycerides and fatty acids enter absorptive cells in the small intestine through micelles; they leave micelles and recombine into chylomicrons, which then enter the bloodstream. Fat-soluble vitamins are absorbed in the same manner as lipids; water-soluble vitamins can be directly absorbed into the bloodstream from the intestine. * Complete analysis questions 2-4 on located page 58 in your composition book.