3.2

Feeding relationships: Producers harness an energy source � through either photosynthesis or chemosynthesis � to convert inorganic substances to organic substances, which contain energy that becomes available to consumers. The rate at which producers transfer energy into organic substances and produce biomass is measured as productivity, and this is affected by factors such as the availability of light. Energy is lost as it passes along a food chain, and this results in a decrease in the energy content of the organisms at each trophic level.