B4.7.4.3

Transfer of biomass

Content

Students should be able to:

  • describe pyramids of biomass
  • explain how biomass is lost between the different trophic levels.
  • Producers are mostly plants and algae which transfer about 1 % of the incident energy from light for photosynthesis.
  • Only approximately 10 % of the biomass from each trophic level is transferred to the level above it.
  • Losses of biomass are due to:
    • not all the ingested material is absorbed, some is egested as faeces
    • some absorbed material is lost as waste, such as carbon dioxide and water in respiration and water and urea in urine.
    • Large amounts of glucose are used in respiration.
    • Students should be able to calculate the efficiency of biomass transfers between trophic levels by percentages or fractions of mass.
    • Students should be able to explain how this affects the number of organisms at each trophic level.

Use ratios, fractions and percentages