Organisation & Trophic Levels - Transfer of Biomass (GCSE Biology)
Transfer of Biomass
Biomass
Transfer of Biomass
Pyramids of biomass are used to show the transfer of biomass.
- In this pyramid, we measure the length of the bars to work out the biomass that is transferred.
- Biomass is lost between trophic levels. Only around 10% of the biomass is transferred. 90% is lost through life processes. This includes excretion of undigested material as faces, respiration giving out carbon dioxide and loss of urea in urine. Respiration uses a huge amount of glucose and so a lot of the biomass is lost here.
Plants as Human Food
- There is greater efficiency in supplying plants as human food. This is because, as we have seen, energy is lost at each trophic level so it is more efficient to directly eat plants rather than animals. Hence, it is more efficient to farm crops to directly feed humans rather than farming crops to feed animals to feed humans.
Biomass Transfer Calculations
Efficiency of biomass transfer calculations can be done in order to measure the proportion of biomass transferred from one trophic level to another.
It is a classic percentage calculation, so you compare the two. You divide the biomass of the higher trophic level by the biomass of the lower trophic level, then multiply this by 100. This gives you a percentage.
So if we had a trophic level 1 with a biomass of 20kg and a trophic level 2 with a biomass of 15kg, the efficiency of biomass would be 15/20 multiplied by 100. This would give us 75%.
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