GCSE Biology (AQA)

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Efficiency of Biomass Transfers

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Ecology Trophic Levels in Ecosystem

Efficiency of Biomass Transfers

3:03 Trophic Levels
Spec 4.7.4.3
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  • Biomass transfer efficiency between trophic levels can be calculated using percentages or fractions of mass.
  • Efficiency of transfer as a percentage is calculated by dividing the biomass in a higher trophic level by the biomass in a lower trophic level and then multiplying by 100.
  • A pyramid of biomass illustrates the biomass at each level of a food chain, including a tree, aphids, birds, and a hawk.
  • The example considers the transfer of mass from a tree (100% mass) to aphids and subsequent levels.
  • The example uses pandas and their diet of bamboo to demonstrate how to calculate biomass transfer efficiency.
  • Steps to calculate efficiency:
  • 1. Identify the command word in the question (e.g., "calculate").
  • 2. Write out the equation needed for calculation.
  • 3. Identify the higher trophic level and input the values.
  • 4. Calculate the answer and include the units.
  • 5. Use the fact that no more than 100% of biomass can be transferred to check the answer.
  • Approximately 10% of biomass is normally transferred between trophic levels.
  • The calculated example shows an 8.6% efficiency of biomass transfer from bamboo to pandas, aligning with expected values.

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