Biology - B4 - Food chains, trophic levels and pyramids of biomass

what is a photosynthetic organism?

• an organism that can photosynthesise so doesn’t need to eat other organisms

• producers, first trophic level

what is the first trophic level?

producers (photosynthetic organisms)

what does a primary consumer eat?

producers (plants)

what do secondary, tertiary, etc consumers eat?

animals

what do the arrows in a food chain represent?

the flow of energy

which part of a food chain is trophic level one?

producer

why are there rarely more than 4 or 5 trophic levels?

energy is lost between trophic levels

• only around 10% of energy is transferred between trophic levels

what are apex predators?

• animals that don’t have a predator themselves

• top of the food chain, highest trophic level

what do pyramids of biomass do and what is their typical shape?

• they show the biomass at eat level of the food chain

• bars get smaller as they go up through the trophic levels, because the total biomass is decreasing

why is biomass lost between trophic levels?

1. organisms don’t usually eat every part of what they eat (eg. bones)

2. not all is broken down/absorbed (eg. fur)

3. most of nutrients are absorbed during respiration for energy

what is the equation for efficiency of biomass transfer?

efficiency = (biomass transferred to next level / biomass at previous level) x 100