In a subtropical grassland, the Gross Primary Production (GPP) is 5000 kJ m⁻² d⁻¹. The energy transfer efficiency from producers to primary consumers is 12 % and from primary consumers to secondary consumers is 8 %. Calculate the amount of energy (in kJ m⁻² d⁻¹) available to secondary consumers.
Answer
48 kJ m⁻² d⁻¹
The correct answer is 48 kJ m⁻² d⁻¹ — Thus the secondary consumers obtain 48 kJ m⁻² d⁻¹.
Step-by-step solution
- Energy reaching primary consumers = GPP × efficiency = 5000 × 0.12 = 600 kJ m⁻² d⁻¹.
- Energy reaching secondary consumers = energy at primary consumers × second efficiency = 600 × 0.08 = 48 kJ m⁻² d⁻¹.
- Thus the secondary consumers obtain 48 kJ m⁻² d⁻¹.
Common mistake: Adding percentages instead of multiplying sequentially
Concept tested: Energy transfer efficiency calculation
Published · How this solution was prepared and checked
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