2.9  Photosynthesis

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Essential Idea:

Photosynthesis uses the energy in sunlight

to produce the chemical energy needed for life


  • Photosynthesis is the production of carbon compounds in cells using light energy
  • Visible light has a range of wavelengths with violet the shortest wavelength and red the longest
  • Chlorophyll absorbs red and blue light most effectively and reflects green light more than other colours
  • Oxygen is produced in photosynthesis from the photolysis of water
  • Energy is needed to produce carbohydrates and other carbon compounds from carbon dioxide
  • Temperature, light intensity and carbon dioxide concentration are possible limiting factors on the rate of photosynthesis


  • Changes to the Earth’s atmosphere, oceans and rock deposition due to photosynthesis


  • Drawing an absorption spectrum for chlorophyll and an action spectrum for photosynthesis
  • Design of experiments to investigate the effect of limiting factors on photosynthesis
  • Separation of photosynthetic pigments by chromatograph