digestive enzymes

• What is the colour change when there is a positive result for glucose?

  Blue to orange-red
• What chemical is used to test for glucose?

  Benedict's
• Why do you need to turn off the Bunsen before using ethanol?

  Ethanol is flammable
• Which nutrient does Biuret test for?

  Protein
• What are carbohydrates needed for?

  Energy
• What is a partially permeable membrane?

  A membrane that allows only substances of a certain size to pass through
• What are the two types of digestion?

  * Mechanical digestion: physical action to break food down

  * Chemical digestion: chemicals break down the food
• What are the three main nutrients in our food?

  Protein, fat, carbohydrate
• What are the characteristics of most food molecules?

  Large and insoluble
• Where do large food molecules need to be broken down to be absorbed?

  Small intestine
• What is the purpose of digestion?

  To break down large molecules into smaller, soluble ones
• What is the function of the digestive system?

  The digestive system breaks down large food molecules into smaller, soluble ones that can be absorbed and utilized by the body.
• What is the "lock and key" model of enzyme action?

  Enzyme binds to specific substrate, breaking it down into products
• What is the role of the active site in enzyme action?

  Specific binding site for substrate
• What are the three main types of digestive enzymes?

  * Carbohydrase (e.g. amylase): breaks down carbohydrates into simple sugars

  * Protease: breaks down proteins into amino acids

  * Lipase: breaks down fats into fatty acids and glycerol
• Which enzyme breaks down carbohydrates?

  Carbohydrase (e.g. amylase)
• What is the product of carbohydrate breakdown by carbohydrase?

  Simple sugars (e.g. glucose)
• Which enzyme breaks down proteins?

  Protease
• What are the products of protein breakdown by protease?

  Amino acids
• Which enzyme breaks down fats?

  Lipase
• What are the products of fat breakdown by lipase?

  Fatty acids and glycerol
• Why can't carbohydrase enzymes digest proteins?

  Proteins do not fit in the active site of carbohydrase
• How does the experiment with Visking tubing demonstrate digestion and absorption?

  The Visking tubing represents the semi-permeable membrane of the small intestine. The starch solution inside the tubing represents the large food molecules that need to be broken down. The amylase enzyme breaks down the starch into glucose, which can then diffuse out of the tubing into the surrounding water (representing the bloodstream).