Photosynthesis (AQA GCSE Combined Science: Synergy: Life & Environmental Sciences): Revision Note

The Process of Photosynthesis

• Plants make their own food using light, water and carbon dioxide

  • This is why they are called producers in food chains

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

  • The leaves of the plant are where most photosynthesis takes place, in specialised mesophyll cells which are packed with chloroplasts containing chlorophyll to absorb as much light energy as possible

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

• These reactions can be summarised into a simple equation

Word equation for photosynthesis

• The reactants for photosynthesis are obtained by a plant as follows:

   

Plants obtain the materials they need for photosynthesis from the environment

Balanced symbol equation for photosynthesis (Higher Tier Only)

Balanced symbol equation for photosynthesis

Uses of glucose in plants

• The glucose produced in photosynthesis may be:

  • Used for respiration (both aerobic and anaerobic)

  • Converted into insoluble starch for storage in the stems, leaves and roots

  • Used to produce fat or oil for storage (especially in seeds)

  • Used to produce cellulose, which strengthens the cell wall

  • Combined with nitrate ions absorbed from the soil to produce amino acids for protein synthesis

The main uses of glucose in a plant