B4 - Bioenergetics

• Bioenergetics


  The study of the energy transformations that occur in living organisms
• Factors Affecting Photosynthesis

  • Temperature
  • Carbon dioxide concentration
  • Light intensity
• As the temperature increases


  The rate of photosynthesis increases
• As the temperature approaches 45°C


  The rate of photosynthesis drops to zero because the enzymes controlling photosynthesis have been destroyed
• As the concentration of carbon dioxide increases


  The rate of photosynthesis increases
• As light intensity increases


  The rate of photosynthesis increases
• After reaching a certain point, any increase in a factor has no further effect as it is no longer the limiting factor
• Photosynthesis


  Carbon dioxide + Water -> Glucose + Oxygen
• Endothermic


  Reactions that take in heat/require heat energy
• Chlorophyll


  The green pigment found in most plants; responsible for photosynthesis
• Limiting factor


  A factor that prevents a reaction going any faster
• Inverse square law

  When a light source is moved to double the distance then the light intensity reduces by a quarter
• Aerobic respiration


  Glucose + Oxygen -> Carbon dioxide + Water
• Anaerobic respiration in animals

  Glucose -> Lactic acid
• Anaerobic respiration in plants and yeast

  Glucose -> Ethanol + Carbon dioxide
• Exothermic

  Reactions that release energy/heat into the environment
• Aerobic respiration


  Respiration that uses oxygen to release energy from glucose
• Anaerobic respiration


  Respiration that takes place without oxygen, producing energy and lactic acid
• Fermentation


  The conversion of sugar to alcohol and carbon dioxide in yeast
• Lactic acid


  A compound produced when cells respire without oxygen (i.e. anaerobically)
• Oxygen debt


  Oxygen deficiency caused by anaerobic respiration during intense/vigorous exercise
• Metabolism


  The sum of all the chemical reactions occurring in the body
• Anaerobic respiration in animals:

  Glucose -> Lactic acid
• Anaerobic respiration in plants/yeast:

  Glucose -> Ethanol + Carbon dioxide
• Photosynthesis required practical:

  1. Place pondweed in a beaker (with sodium hydrogen carbonate to add CO2) and shine light at it from a set distance away
  2. Record the number of gas bubbles that come out of the pond weed in 1 minute
  3. Repeat this with the lamp at different distances from the weed
• Photosynthesis required practical:

  •Independent Variable - light intensity (distance from the light)

  •Dependent Variable - number of bubbles per minute

  •Control Variables - mass of pondweed, temperature, concentration of carbon dioxide
• Plants use glucose for:

  • Respiration

  • Making cellulose

  • Making amino acids

  • Storing as oils or fats

  • Storing as starch
• Light intensity is proportional to 1÷ distance^2
• Farmers increase photosynthesis rates by manipulating conditions such as light, temperature, and carbon dioxide concentration
• Metabolism is all the chemical reactions in an organism