Module 2

• Exothermic reactions


  Reactions that transfer energy to the surroundings (i.e. the energy from the reaction exits from the reaction)
• Exothermic reactions


  • The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become hotter
  • A thermometer is used to detect temperature increase
• Endothermic reactions


  Reactions that take in energy from the surroundings (i.e. the energy enters the reaction)
• Endothermic reactions


  • The energy is usually transferred as a heat energy, causing the reaction mixture and its surroundings to become colder
  • A thermometer is used to detect temperature decrease
• Anaerobic respiration occurs without oxygen and releases less energy more quickly than aerobic respiration
• Factors affecting photosynthesis


  • Light intensity
  • Carbon dioxide concentration
  • Temperature
• Increasing the light intensity


  Increases the rate of photosynthesis, until the rate plateaus
• Increasing the carbon dioxide concentration


  Increases the rate of photosynthesis, until the rate plateaus
• As temperature increases


  The rate of photosynthesis increases, until an optimum temperature where the enzymes involved denature and the rate decreases
• Anaerobic respiration in humans


  During exercise, when there is not enough oxygen for aerobic respiration, anaerobic respiration occurs instead, producing lactic acid
• Anaerobic respiration in bacteria and fungi

  Anaerobic respiration is called fermentation, producing ethanol
• Enzymes


  Proteins that function as biological catalysts, speeding up a reaction without being changed by it
• Enzymes


  • The active site matches the shape of the substrate molecules
  • If exposed to high pH or temperatures, the shape of the active site can change, causing the enzyme to denature
  • Enzymes work best at their optimum pH
• Enzymes that break down different molecules


  • Carbohydrate enzymes break down carbohydrates
  • Lipase enzymes break down fats
  • Protease enzymes break down proteins
• Calorimeters


  Measure the energy stored within a food
• Starch is tested for using iodine
• Rate of reaction


  Substrate used / Amount of time taken
• Amylase


  A carbohydrase enzyme found in the mouth