In a grassland ecosystem, the Gross Primary Production (GPP) is 4000 kJ m⁻² d⁻¹. The energy transfer efficiency from producers to herbivores is 10 % and from herbivores to carnivores is 12 %. Calculate the overall efficiency (in percent) of energy transfer from primary producers to carnivores.
Answer
1.2 %
The correct answer is 1.2 % — Overall efficiency = (48 kJ / 4000 kJ) × 100 % = 1.2 %.
Step-by-step solution
- Energy available at the producer level = 4000 kJ.
- Transfer to herbivores = 10 % of 4000 kJ = 400 kJ.
- Transfer to carnivores = 12 % of 400 kJ = 48 kJ.
- Overall efficiency = (48 kJ / 4000 kJ) × 100 % = 1.2 %.
Common mistake: Multiplying percentages instead of applying them sequentially
Concept tested: Energy transfer efficiency
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