Primary Producers (AQA A Level Biology)

Plants are Primary Producers

• An ecosystem in a particular area includes:

  • All the living components (i.e. biotic factors such as organisms and their interactions)

  • All the non-living components (i.e. abiotic factors such as temperature and rainfall)

• All ecosystems include (and depend on) primary producers

  • Primary producers are organisms that make their own glucose

  • For example, plants and algae produce glucose via photosynthesis

  • Even deep-sea ecosystems such as those around hydrothermal vents (where there is no light) depend on primary producers (in this case bacteria) that use a process known as chemosynthesis to make glucose from the chemicals released from these vents

• 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

  • In terrestrial (land-based) ecosystems, plants use CO₂ from the atmosphere

  • In aquatic (water-based) ecosystems, plants use CO₂ dissolved in the water

• The process of photosynthesis transforms light energy into chemical energy held in biological molecules

• The chemical energy in these biological molecules can then be used by other organisms within the community known as consumers (i.e. the organisms in higher trophic levels)

  • Primary consumers (herbivores or omnivores) feed on producers

  • Secondary consumers (carnivores or omnivores) feed on primary consumers

  • Tertiary consumers (carnivores or omnivores) feed on secondary consumers

Trophic levels for a simple food chain - the blue arrows show how the chemical energy originally produced by the primary producer (grass) is transferred to other organisms in the community