AQA A Level Biology

Revision Notes

5.3.2 Photosynthetic Products

Photosynthetic Products

  • The process of photosynthesis transfers light energy to chemical energy in biological molecules
  • In ecosystems where sunlight and water is available, the process of photosynthesis enables plants to synthesise organic compounds (glucose and other sugars) from carbon dioxide
  • Most of these sugars synthesised by plants are used by the plant as respiratory substrates
    • A respiratory substrate is a molecule (such as glucose) that can be used in respiration, to release energy for growth
  • The remaining sugars (not used in respiration) are used to make other groups of biological molecules, such as:
    • Starch – a complex carbohydrate molecule (formed from many glucose molecules) that acts as a short-term energy storage molecule
    • Cellulose – another complex carbohydrate molecule (also formed from many glucose molecules) that acts as a structural component of plant cell walls
    • Lipids – plant cells can convert the sugars produced during photosynthesis into lipids, which act as another type of (longer-term) energy storage molecule
    • Proteins – plant cells can also combine the sugars produced during photosynthesis with nitrates to make amino acids, which can then be used to produce proteins
  • These different groups of biological molecules (all formed from the sugars synthesised by plants during photosynthesis) make up the biomass of the plants
    • The biomass is the mass of living material
    • The biomass can also be thought of as the chemical energy that is stored within the plant

Photosynthetic product uses (1), downloadable AS & A Level Biology revision notesPhotosynthetic product uses (2), downloadable AS & A Level Biology revision notesPhotosynthetic product uses (3), downloadable AS & A Level Biology revision notes

The sugars synthesised during photosynthesis can be used in respiration or the creation of other biological molecules needed by plants

Author:

Alistair graduated from Oxford University in 2014 with a degree in Biological Sciences. He has taught GCSE/IGCSE Biology, as well as Biology and Environmental Systems & Societies for the International Baccalaureate Diploma Programme. While teaching in Oxford, Alistair completed his MA Education as Head of Department for Environmental Systems and Societies.
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