Bio B4 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

  
• 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 volume

  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 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


  Glucose + oxygen → carbon dioxide + water
• Anaerobic respiration


  Occurs when there is not enough oxygen, does not yield as much energy as aerobic respiration, used as a last resort
• 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
• Examples of metabolic reactions


  • Glucose molecules being converted to starch, glycogen and cellulose
  • A glycerol molecule and three molecules of fatty acids forming a lipid molecule
  • Glucose and nitrate ions forming amino acids, which are used to form proteins
  • The reactions in respiration
  • Urea forming from the breakdown of proteins for excretion