Pyramids of Biomass

• What do pyramids of biomass show?

  The biomass of each trophic level
• In the given food chain, what is the producer?

  Grass
• What does the term biomass refer to?

  The mass of living organisms
• What does the bottom bar in the pyramid represent?

  Total mass of all the grass
• Why do the bars in the biomass pyramid get smaller as you go up?

  Total mass of organisms decreases at each level
• Why is the total mass of snakes lower than that of rabbits?

  Fewer snakes than rabbits exist
• What happens to biomass and energy when one organism is consumed by another?

  Most is lost or used, only 10% transfers
• What percentage of biomass is typically transferred to the next trophic level?

  About 10%
• What is one reason why not all biomass is consumed?

  Organisms don't eat every part
• What happens to the parts of organisms that are not absorbed?

  They are excreted as feces
• What is the main reason nutrients absorbed are not stored as biomass?

  Used for energy through respiration
• How is the efficiency of biomass transfer calculated?

  Efficiency = biomass transferred / biomass available
• What is the efficiency of biomass transfer from rabbits to snakes if 15 kg is transferred from 144 kg available?

  10.4%
• What is the efficiency of biomass transfer from snakes to hawks if 1.6 kg is transferred from 15 kg available?

  10.7%
• What are the main reasons only 10% of biomass and energy gets passed on each time?

  1. Organisms don't eat every part.
  2. Not all consumed parts are absorbed.
  3. Most nutrients are used for respiration.
• How do you calculate the efficiency of biomass transfer?

  • Use the formula:

  Efficiency = (biomass transferred / biomass available) × 100