Bioenergetics

• Photosynthesis


  Carbon dioxide + water ➡️ glucose + oxygen
• Photosynthesis


  An endothermic reaction in which energy is transferred from the environment to the chloroplasts by light
• Factors affecting rate of photosynthesis

  • Temperature
  • Light intensity
  • Carbon dioxide concentration
  • Amount of chlorophyll
• Measuring and calculating rates of photosynthesis


  1. Measure

  2. Extract and interpret graphs

  3. Plot and draw appropriate graphs

  4. Translate information between graphical and numeric form
• Factors that limit photosynthesis interact and any one of them may be the limiting factor
• Inverse proportion, inverse square law and light intensity are important in the context of photosynthesis
• Limiting factors are important in the economics of enhancing the conditions in greenhouses to gain the maximum rate of photosynthesis while still maintaining profit
• Uses of glucose produced in photosynthesis

  • Used for respiration
  • Converted into insoluble starch for storage
  • Used to produce fat or oil for storage
  • Used to produce cellulose, which strengthens the cell wall
  • Used to produce amino acids for protein synthesis
• To produce proteins, plants also use nitrate ions that are absorbed from the soil
• Cellular respiration


  Glucose + oxygen ➡️ carbon dioxide + water
• Cellular respiration


  An exothermic reaction which is continuously occurring in living cells to transfer energy needed for living processes
• Aerobic respiration


  Respiration using oxygen
• Anaerobic respiration


  Respiration without oxygen
• Organisms need energy for


  • Chemical reactions to build larger molecules
  • Movement
  • Keeping warm
• Anaerobic respiration in muscles


  Glucose ➡️ lactic acid
• Anaerobic respiration transfers much less energy than aerobic respiration
• Anaerobic respiration in plant and yeast cells

  Glucose ➡️ ethanol + carbon dioxide
• Anaerobic respiration in yeast cells


  Fermentation, has economic importance in the manufacture of bread and alcoholic drinks
• Human body's reaction to increased energy demand during exercise


  1. Heart rate, breathing rate and breath volume increase to supply muscles with more oxygenated blood

  2. If insufficient oxygen, anaerobic respiration takes place in muscles, causing lactic acid buildup and oxygen debt

  3. During long periods of vigorous activity, muscles become fatigued and stop contracting efficiently
• 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
• Blood flowing through the muscles transports the lactic acid to the liver where it is converted back into glucose
• Importance of sugars, amino acids, fatty acids and glycerol


  • Synthesis and breakdown of carbohydrates, proteins and lipids
• Metabolism


  The sum of all the reactions in a cell or the body, using the energy transferred by respiration for continual enzyme controlled processes that synthesise new molecules
• Aspects of metabolism


  • Conversion of glucose to starch, glycogen and cellulose
  • Formation of lipid molecules from glycerol and fatty acids
  • Use of glucose and nitrate ions to form amino acids for protein synthesis
  • Respiration
  • Breakdown of excess proteins to form urea for excretion