A scientist studied the energy transfer in a population of primary consumers feeding on a crop. The energy values recorded over a set period are shown in the table below:
| Energy pathway | Value |
|---|---|
| Chemical energy in ingested food (III) | 320 kJ |
| Chemical energy lost in faeces | 120 kJ |
| Chemical energy lost in urine | 16 kJ |
| Respiratory losses (RRR) | 112 kJ |
Using the equation N=I−(F+R)N = I - (F + R)N=I−(F+R), calculate the percentage of the chemical energy in the ingested food that is converted into the net productivity (NNN) of these consumers.
22.5%22.5\%22.5%
27.5%27.5\%27.5%
39.1%39.1\%39.1%
62.5%62.5\%62.5%
67 exam-style questions on OCR GCSE Biology 4.1 Ecosystems, covering 4.1.1 Cycling of materials in ecosystems, 4.1.2 Microorganisms in cycling materials, 4.1.3 The carbon and water cycles, 4.1.4 Factors affecting decomposition, 4.1.5 Levels of organisation in an ecosystem, 4.1.6 Abiotic and biotic factors affecting communities, 4.1.7 Interdependence and competition, 4.1.8 Trophic levels, 4.1.9 Pyramids of biomass, and 4.1.10 Efficiency of biomass transfers. Each one has a worked solution and a mark scheme showing where the marks go.