B8-Photosynthesis

• Photosynthesis


  The process by which plants make food (glucose) using the Sun's energy
• Photosynthesis


  1. Carbon dioxide + water + light energy

  2. Glucose + oxygen
• Photosynthetic reaction


  An endothermic reaction that needs an input of energy from the environment
• The word equation for photosynthesis is: carbon dioxide + water -> light -> glucose + oxygen
• The balanced symbol equation for photosynthesis is: 6CO2 + 6H2O -> light -> C6H12O6 + 6O2
• You need to be able to recognise the chemical symbols for these molecules
• Factors affecting rate of photosynthesis

  • Carbon dioxide concentration
  • Light intensity
  • Temperature
  • Amount of chlorophyll
• As carbon dioxide concentration increases

  The rate of photosynthesis increases up to a point
• As light intensity increases

  The rate of photosynthesis increases up to a point
• As temperature increases


  The rate of photosynthesis increases up to a point, then decreases as enzymes become denatured
• Variegated leaves have white and green areas, the white areas do not have chlorophyll so the rate of photosynthesis is reduced
• Limiting factors


  • Any one environmental factor that limits the rate of photosynthesis
• In nature, more than one environmental factor varies and the rate of photosynthesis is due to the interaction of these factors
• Farmers control environmental factors in greenhouses to maximise photosynthesis and crop yields
• Uses of glucose from photosynthesis

  • To produce cellulose to strengthen plant cell walls
  • To be converted into insoluble starch for storage
  • To be converted into amino acids for protein synthesis
  • To produce fat or oil for storage
  • To provide energy through respiration