Photosynthetic Reaction (AQA GCSE Combined Science: Trilogy: Biology): Revision Note

Photosynthesis

• Photosynthesis is:

an endothermic reaction in which energy is transferred from the environment to the chloroplasts by light

• The light energy is absorbed by chlorophyll, the green pigment in the chloroplasts

• During photosynthesis plants make their own sugars from water and carbon dioxide

  • This is why they are called producers in food chains

• The sugars produced during photosynthesis are used to make all the substances a plant needs, as well as being used in respiration to release energy

• These reaction can be summarised in the word equation:

carbon dioxide + water → glucose + oxygen

• The reaction can also be written as a chemical symbol equation

  • CO₂ = carbon dioxide

  • H₂O = water

  • C₆H₁₂O₆ = glucose

  • O₂ = oxygen

6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂

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