4.7 - 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 role do snakes play in the food chain?

  Secondary consumers
• What is the term biomass defined as?

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

  Total mass of all grass
• What trend is observed in the biomass pyramid as you move up trophic levels?

  The bars get smaller
• Why is the total mass of snakes lower than that of rabbits?

  Fewer snakes than rabbits exist
• What percentage of biomass and energy is typically transferred to the next trophic level?

  About 10%
• What happens to most of the biomass and energy when one organism is consumed by another?

  It is lost or used
• What is one reason why not all biomass is transferred to the next level?

  Not all parts are eaten
• What happens to the parts of organisms that are not absorbed?

  They are excreted as feces
• How do animals primarily use the nutrients they absorb?

  To release energy through respiration
• What is the formula to calculate the efficiency of biomass transfer?

  Efficiency = (biomass transferred / biomass available) × 100
• If the biomass transferred to snakes is 15 kg and the biomass available from rabbits is 144 kg, what is the efficiency?

  $10.4\%$
• What is the efficiency between snakes and hawks if the biomass transferred is 1.6 kg and the biomass available is 15 kg?

  $10.7\%$
• What are the main reasons only 10% of biomass and energy gets passed on in a food chain?

  • Not all parts of organisms are eaten
  • Some parts are not absorbed and excreted
  • Most nutrients are used for energy through respiration
• How does the biomass pyramid illustrate energy transfer in a food chain?

  • Shows decreasing biomass at each trophic level
  • Represents the mass of living organisms at each level
  • Highlights inefficiencies in energy transfer