23.2 biomass transfer through a system

producer

an organism that converts light energy into chemical energy by the process of photosynthesis

consumers

organisms that obtain their energy by feeding on other organisms

different trophic levels

producer

primary consumer

secondary consumer

tertiary consumer

quaternary consumer

ecological efficiently

the efficiency with which biomass or energy is transferred from one trophic level to another

why do producers only convert a small amount of sun energy into chemical energy

• not all of the solar energy is available for photosynthesis - 90% is reflected and some of it is of an unusable wavelength

• other factors may limit photosynthesis

• a proportion of the energy is lost as it is used for photosynthetic reactions

formula for calculating energy that moves onto the next trophic level

net production = total production - respiratory losses

biomass

the mass of living material present in a particular place or in particular organisms

how to calculate biomass at each trophic level

multiply the biomass present in each organism by the total number of organisms at that trophic level

organisms have to be dried out to make the results more reliable so the organisms are placed in an oven at 80 degrees until all the water has evaporated

reasons why only 10% of the biomass in their food is converted to their own organic tissue

• not all of the biomass of an object is eaten, for example, plant roots or animal bones may not be consumed

• some energy is transferred to the environment as metabolic heat, as a result of movement and respiration

• some parts of an organism are eaten but are indigestible - these are egested as faces

• some energy is lost in excretory matter

formula to calculate the efficiency of the energy transfer between each trophic level of a food chain

ecological efficiency = energy or biomass available after the transfer / energy of biomass available before the transfer x 100

how do human activities manipulate biomass

• agriculture means that plants are provided with the abiotic conditions they need to thrive and competition and predators threat is taken away

• this creates very simple food chains which means that the minimal amount of energy is lost before food is consumed by humans