8.6 - Pyramids of biomass

• Biomass

  The mass of living organisms in a given area
• What does each bar in a pyramid of biomass represent?

  The biomass of all organisms in that trophic level
• What happens as you go up the bars?

  The bars get smaller.
• Why do the bars get smaller as they go up?

  Because the total mass of the organisms is decreasing
• How much energy and biomass is transferred up to the next trophic level?

  10%
• What does the biomass of an organism refer to?

  The mass of an organism
• Where are apex predators on a pyramid of biomass?

  At the top of the pyramid
• Give three reasons why only ~10% of the energy & biomass is passed on at each stage in a food chain?

  - Organisms don't normally eat every part of their food (e.g. rabbits may not eat the roots of the grass they eat)

  - Some of the material they eat may not be absorbed (e.g. rabbits may not be able to digest all the cellulose in grass)

  - Most of the biomass/energy that is absorbed is used to release energy (via respiration) for movement etc.
• What is the formula for efficiency of biomass transfer?

  Biomass in current trophic level / biomass available in previous level X 100