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Energy & Biomass Pyramids quiz #3

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  • Why is trophic efficiency typically low in ecosystems, and what are the main factors that contribute to this low efficiency?
    Trophic efficiency is typically low, averaging around 10%, due to incomplete ingestion, incomplete digestion, energy used for metabolism and cellular respiration, and heat loss during energy transfer between trophic levels.
  • What does an energy pyramid represent in an ecosystem?
    An energy pyramid shows the transfer of energy between trophic levels over time, always maintaining an upright shape due to low trophic efficiency.
  • Why are energy pyramids always upright in shape?
    Energy pyramids are always upright because energy transfer between trophic levels is inefficient, with only a small fraction moving up each level.
  • How do the units of measurement differ between energy pyramids and biomass pyramids?
    Energy pyramids use units of energy per area per time (e.g., joules/m²/month), while biomass pyramids use units of mass per area (e.g., grams/m²) without a time component.
  • Why can biomass pyramids take on shapes other than upright, such as inverted or diamond-shaped?
    Biomass pyramids can be inverted or diamond-shaped because they represent a snapshot in time, not accounting for rapid reproduction or consumption rates.
  • What is trophic efficiency and what is its typical value in ecosystems?
    Trophic efficiency is the percentage of energy transferred from one trophic level to the next, typically averaging around 10%.
  • List two reasons why trophic efficiency is low in ecosystems.
    Trophic efficiency is low due to incomplete ingestion and incomplete digestion, meaning not all available energy is consumed or assimilated.
  • How does metabolism and cellular respiration affect energy transfer between trophic levels?
    Energy used for metabolism and cellular respiration is not available for transfer to the next trophic level, reducing trophic efficiency.
  • What is biomagnification and which organisms are most affected by it?
    Biomagnification is the process by which pollutants become more concentrated at higher trophic levels, most significantly impacting top consumers.
  • Why do pollutants become more concentrated in organisms at higher trophic levels?
    Pollutants accumulate in biomass because they cannot be digested or excreted, leading to higher concentrations as they move up the food chain.
  • In an ecosystem, which trophic level typically has the least biomass?
    The highest trophic level, usually the top consumers, typically has the least biomass in an ecosystem.