Pyramids and transfer of biomass

• what is biomass?

  dry mass of all the living organisms in an area
• why is dry mass used for biomass?

  because wet mass varies as the volume of water in the organism varies
• equation of efficiency of biomass transfer

  = (energy transferred/total energy available) x 100
• what percentage of the incident energy from for photosynthesis do producers transfer?

  1%
• what percentage of the biomass from one trophic level is transferred to the level above it in feeding?

  approx 10%
• why are biomass transfers not 100% efficient?

  • energy is lost:egestion (removal of faeces)
  • excretion (removal of waste products)
  • respiration (loss of CO2 and water) in which large amounts of glucose are used
  • production of inedible bones and shells
• how does the efficiency of biomass transfers affect the number of trophic levels in a biomass pyramid?

  the less efficient the transfers, the fewer trophic levels and the fewer organisms in higher trophic levels
• what is a biomass pyramid?

  pyramid that shows the total dry mass of organisms at each trophic level
• what is a pyramid of numbers?

  shows the number of organisms at each trophic level
• why are some pyramids of numbers not pyramid shaped?

  don’t take size and mass of organisms into account