topic 4 bioenergetics

• Photosynthesis

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


  Energy is transferred from the environment to the chloroplasts by light
• Photosynthesis


  Carbon dioxide + water → glucose + oxygen
• Factors affecting rate of photosynthesis


  • Temperature
  • Light intensity
  • Carbon dioxide concentration
  • Amount of chlorophyll
• 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 levelling 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 greenhouse conditions for greater rate of photosynthesis
• Inverse proportion


  Relationship where one factor increases as another 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
• Aerobic respiration


  Uses oxygen, yields the most energy, most reactions occur in mitochondria
• Aerobic respiration equation


  Glucose + oxygen → carbon dioxide + water
• Anaerobic respiration


  Occurs when there is not enough oxygen, does not yield as much energy as aerobic respiration, oxidation of glucose is incomplete
• Anaerobic respiration in animals


  Glucose → lactic acid
• Anaerobic respiration 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 forming lipids
  • Glucose and nitrate forming amino acids and proteins
  • Reactions in respiration
  • Urea forming from protein breakdown