2.2.1 The Human Digestive System

• What is the digestive system an example of?

  An organ system.
• What is the function of the digestive system?

  To digest and absorb food.
• What is an enzyme?

  A protein which acts as a catalyst.
• What is a catalyst?

  A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.
• What is the lock and key model?

  The model which shows the substrate attaching to the active site of the enzyme and forming new products.
• What is the role of digestive enzymes?

  To convert food into small soluble molecules that can be absorbed into the bloodstream.
• What is a carbohydrase?

  An enzyme which converts carbohydrates to simple sugars.
• What is amylase?

  A carbohydrase which breaks down starch.
• Which three places is amylase produced in?

  Salivary glands, the pancreas and the small intestine.
• Starch -> amylase enzyme -> maltose and other sugars
• What is a protease?

  An enzyme which breaks down proteins.
• Which three places is protease produced in?

  The stomach, pancreas and small intestine.
• Proteins -> protease enzyme -> amino acids
• What is a lipase?

  An enzyme which breaks down lipids.
• What two places are lipases produced in?

  The pancreas and small intestine.
• Lipid -> lipase enzyme -> glycerol and fatty acids
• What are the products of respiration used for?

  To build new carbohydrates, proteins and lipids. Some glucose is also used in respiration.
• Bile is made in the liver and stored in the gall bladder. It is alkaline to neutralise hydrochloric acid from the stomach. It also emulsifies fat to form small droplets which increases the surface area. The alkaline conditions and large surface area increase the rate of fat breakdown by lipase.
• What is the optimum temperature of an enzyme?

  35°C.
• What is the optimum pH of an enzyme?

  7.
• What is the optimum pH of pepsin?

  2.
• What does an enzyme become after optimum conditions are exceeded?

  Denatured.