Biology Digestion PDF
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Uploaded by BullishPixie
Haverfordwest High VC School
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Summary
This document provides information on digestive enzymes, breakdown products, food tests, and the process of calculating food energy content. It explains the role of enzymes like proteases, lipases, and amylases in breaking down food types like proteins, fats, and carbohydrates.
Full Transcript
Digestive Enzymes Food Type Digestive Enzyme Breakdown Uses in Body Product Proteins Proteases Amino acids Growth & repair of...
Digestive Enzymes Food Type Digestive Enzyme Breakdown Uses in Body Product Proteins Proteases Amino acids Growth & repair of tissues Fats (lipids) Lipases Fatty acids & Energy + insulation glycerol Starch Amylase Glucose Energy (carbohydrate) (carbohydrase) Food Tests Food Food Test Method Positive Result Reagent Protein Biuret Add Biuret solution Lilac Starch Iodine Add iodine solution Blue-black Glucos Benedict’s Boil with Benedict’s solution Green to blue to orange e ppt Experiment: Calculating Energy Content of Food 1. Weigh the food sample and note its mass. 2. Pierce the food with a mounted needle. 3. Ignite the food and place it under a test tube filled with water. 4. Measure the initial and final temperature of the water. Use the formula: Energy released from food per gram (J) = mass of water (g) × temperature rise (°C) × 4.2 ÷ mass of food sample Food enters the mouth where it is chewed and mixed with saliva. Amylase (a carbohydrase enzyme) in the saliva begins the digestion of starch into glucose. The food is then swallowed. It passes down the oesophagus (gullet) to the stomach. The stomach secretes the enzyme protease, which begins digesting protein to amino acids. Hydrochloric acid produced by the stomach kills bacteria and provides the optimum pH for the protease enzymes to act on protein in the food. From the stomach, the food enters the small intestine. Secretions from the liver and pancreas enter the small intestine as the food leaves the stomach. The pancreas secretes lipases, proteases and carbohydrases into the small intestine. In the small intestine, the carbohydrase enzymes digest starch to glucose. Proteins are also digested by protease enzymes, forming amino acids. The fats are digested by lipase enzymes, forming fatty acids and glycerol. The food now continues its journey along the small intestine and further digestion of carbohydrates, fats and proteins takes place. Any undigestible material enters the large intestine. Here, the excess water is removed, forming faeces which are then egested from the body through the anus.
