Percentage efficiency of energy transfer
Calculating the efficiency of energy transfers
Energy is transferred along food chains, however, the amount of available energy decreases from one trophic level to the next. The reason for this is that only around 10 per cent of the energy is passed on to the next trophic level.
The rest of the energy passes out of the food chain in a number of ways:
- it is released as heat energy during respiration
- it is used for life processes (eg movement)
- it is egested in faeces or remains in dead organisms which are passed to An organism which eats dead organisms, fallen leaves, animal droppings, etc, and breaks them down into simpler materials.
Less energy is transferred at each level of the food chain so the The dry mass of an organism. gets smaller.
The percentage efficiency of energy transfer between trophic levels can be calculated using this equation.
\(\text{efficiency} = \frac{\text{energy transferred to next level}}{\text{total energy in}} \times 100\)
Question
- How much energy does A have at the start of the chain?
- How much energy is transferred from A to B?
- Calculate the efficiency of this transfer using the equation.
- 4,500 kJ + 500 kJ = 5,000 kJ
- 500 kJ
- 500 kJ ÷ 5,000 kJ × 100 = 10%