Transfer of Substances & Energy Along a Food Chain (Edexcel IGCSE Biology: Double Science)

• Energy flows from the sun to the first trophic level (producers) in the form of light
• Producers convert light energy into chemical energy
  • This occurs during photosynthesis, when producers convert carbon dioxide and water into glucose and oxygen

• Producers use this glucose (during respiration) to produce their own biomass
  • Biomass is a store of chemical energy

• When primary consumers consume (eat) producers, they break down the biomass of the producer (digestion) and use the chemical energy to increase or sustain their own biomass
• When secondary consumers consume (eat) primary consumers, they break down the biomass of the primary consumer (digestion) and use the chemical energy to increase or sustain their own biomass, and so on
• In this way, as chemical energy is transferred from one trophic level to the next, biomass is also transferred

Calculating the efficiency of energy and biomass transfers

• You may be asked to calculate the efficiency of energy and biomass transfers between trophic levels using percentages