7.4 Trophic levels in an ecosystem (biology only)

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Question 19
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Some farmers keep pigs indoors in temperature-controlled buildings. Other farmers keep pigs outdoors in open fields.

The table below shows the energy inputs and energy outputs for keeping pigs in both systems:

Energy in kJ/m2/year\text{kJ/m}^2/\text{year}kJ/m2/yearIndoorsOutdoors
Input as feed15,00015,00015,0008,8008,8008,800
Input as electricity and heating5,0005,0005,000200200200
Output as meat150150150181818
a.

Calculate the total energy input for keeping pigs outdoors. Use data from the table.

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b.

The total energy input for keeping pigs indoors is 20,000 kJ/m2/year20,000\text{ kJ/m}^2/\text{year}20,000 kJ/m2/year. Calculate the percentage efficiency of keeping pigs indoors.

Use the equation: percentage efficiency=energy outputtotal energy input×100\text{percentage efficiency} = \frac{\text{energy output}}{\text{total energy input}} \times 100percentage efficiency=total energy inputenergy output​×100

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7.4 Trophic levels in an ecosystem (biology only) Questions

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