Bioenergetics

• Photosynthesis


  The process by which plants make glucose from sunlight
• Endothermic reaction


  A reaction in which energy is transferred from the environment to the chloroplasts by light
• Photosynthetic reaction


  Carbon dioxide + water → glucose + oxygen
• Carbon dioxide


  CO2
• Water


  H2O
• Oxygen


  O2
• Glucose


  C6H12O6
• Factors affecting rate of photosynthesis

  • Temperature
  • Light intensity
  • Carbon dioxide concentration
  • Amount of chlorophyll
• Measuring oxygen production to calculate rate of photosynthesis

  1. Pondweed in test tube

  2. Capillary tube and syringe

  3. Lamp at measured distance

  4. Measure distance bubble moves to calculate oxygen produced

  5. Control variables except independent variable
• Limiting factor


  An environmental condition (such as light intensity) which, in low levels, restricts any increase in the rate of photosynthesis
• Graphs showing limiting factors

  • One line leveling off showing one limiting factor
  • Two lines showing two limiting factors
  • Three lines showing three limiting factors
• Farmers can use knowledge of limiting factors to enhance conditions in greenhouse for greater rate of photosynthesis
• Inverse proportion


  Relationship between two factors where one increases while the other decreases
• Inverse square law


  Light intensity is inversely proportional to the square of the distance
• Uses of glucose from photosynthesis

  • For respiration
  • Converted into insoluble starch for storage
  • To produce fat or oil for storage
  • To produce cellulose to strengthen cell walls
  • Combined with nitrates to form amino acids which produce proteins
• Respiration


  The process of transferring energy from glucose so living processes can occur
• Exothermic


  Energy is transferred to the environment
• Types of respiration


  • Aerobic (with oxygen)
  • Anaerobic (without oxygen)
• Response to exercise


  1. Heart rate increasing

  2. Breathing rate increasing

  3. Breath volume increasing
• Anaerobic respiration


  In animals: Glucose → Lactic acid

  In plants and yeast: Glucose → Ethanol + Carbon dioxide
• Oxygen debt


  The amount of extra oxygen the body needs after exercise to react with the accumulated lactic acid and remove it from the cells
• Metabolism


  The sum of all the reactions in a cell or the body, controlled by enzymes
• Metabolic reactions


  • Glucose to starch, glycogen and cellulose

  Glycerol and fatty acids to lipids

  Glucose and nitrate to amino acids and proteins

  Respiration reactions

  Urea forming from protein breakdown