Bioenegetics

• Photosynthesis


  The process by which plants use the sun's energy to make glucose from carbon dioxide and water
• Photosynthetic reaction


  The chemical reaction of photosynthesis where carbon dioxide and water are converted into glucose and oxygen using light energy
• Rate of photosynthesis


  The speed at which photosynthesis occurs
• Use of glucose from photosynthesis


  Glucose can be used to produce cellulose, starch, amino acids, fats and oils
• Respiration


  The process by which living cells convert the energy in glucose into a form that the cell can use
• Aerobic and anaerobic respiration

  Respiration can occur with oxygen (aerobic) or without oxygen (anaerobic)
• Response to exercise


  How the body reacts to increased energy demands during exercise
• Metabolism


  The sum of all the chemical reactions that occur in a cell or organism to sustain life
• Bioenergetics


  The study of the energy transformations that occur in living organisms
• Plants make use of the Sun's energy to make food (glucose)
• Photosynthesis is an endothermic reaction because it needs an input of energy from the environment
• Photosynthesis


  1. Carbon dioxide + Water

  2. Light energy

  3. Glucose + Oxygen
• Carbon dioxide


  One of the reactants needed for plants to make glucose
• As carbon dioxide concentration increases

  The rate of photosynthesis increases up to a point
• The maximum rate of photosynthesis is achieved at a concentration of 0.1% carbon dioxide
• Limiting factor


  Another factor that is now preventing the rate of photosynthesis from increasing further
• Possible limiting factors


  • Light intensity
  • Temperature
  • Amount of chlorophyll
• As temperature increases


  The rate of photosynthesis increases
• If temperature increases too much


  Enzymes become denatured and the rate of photosynthesis decreases and stops
• As light intensity increases

  The rate of photosynthesis increases up to a point
• At a certain light intensity, another factor is limiting the rate of photosynthesis
• Inverse square law


  If you double the distance between the plant and the light source you quarter the light intensity
• Investigating the effect of light intensity on photosynthesis in pondweed

  1. Fill boiling tube with sodium hydrogen carbonate solution

  2. Place pondweed in tube

  3. Set up LED lamp at different distances

  4. Count bubbles released in 1 minute

  5. Calculate mean bubbles
• Very high light intensities may slow the rate of photosynthesis due to saturation of enzyme active sites or bleaching of chlorophyll
• If there is a reduction in the amount of chlorophyll available to the plant then the amount of glucose made by photosynthesis will reduce and the plant will not grow as well
• In nature, more than one environmental factor will vary and the rate of photosynthesis is due to the interaction of these factors
• At low light intensity


  The photosynthetic reaction becomes limited
• If light intensity is increased


  The reaction rate also increases
• A different factor is now limiting the rate of photosynthesis at a higher light intensity
• Farmers apply their understanding of limiting factors


  To improve crop yields by controlling conditions in greenhouses
• The farmer must balance the economics of additional costs of heating, lighting and computer systems to achieve maximum photosynthesis whilst still making a profit
• Uses of glucose from photosynthesis

  To produce cellulose, starch, amino acids, fats and oils
• Respiration occurs 24 hours a day, continuously, in all living cells
• Aerobic respiration


  Respiration that occurs with oxygen
• Aerobic respiration


  1. Glucose + Oxygen

  2. Carbon dioxide + Water
• Anaerobic respiration


  Respiration that occurs without oxygen
• Anaerobic respiration in animal cells

  1. Glucose

  2. Lactic acid
• Anaerobic respiration in plant and yeast cells

  1. Glucose

  2. Ethanol + Carbon dioxide
• Anaerobic respiration in yeast cells is called fermentation and is economically important in the manufacture of alcoholic drinks and bread
• Respiration summary


  • Aerobic respiration
  • Anaerobic respiration in animal cells
  • Anaerobic respiration in plant and yeast cells