Food chains, trophic levels and pyramids of biomass

what are food chains

simplified version of a food web, only shows what gets eaten within a community or ecosystem

what do all food chains start with at the bottom

producer - photosynthetic organism such as plant or algae they use the sun’s energy to make biological molecules and once these molecules are incorporated into the plant we call them biomass

what is the order of a food chain

1. producer

2. primary consumer - eats the producer

3. secondary consumer - eats the primary consumer

4. tertiary consumer - eats the secondary consumer

what do food chain show

how energy passes through an ecosystem via direction of arrows

what is a predator

an animal that hunts and kills other animals for food

what is prey

an animal that gets hunted or killed for food by another animal

what is an apex predator

a predator at the top of the food chain without natural predators of its own

omnivores

they eat both producers and other animals eg. bears so in general we place them in trophic level 3 as they eat primary consumers, however as they also eat producers it’s not a perfect fit

why does energy get lost as you go up the trophic levels

because there’s not enough energy to sustain organisms in a higher trophic level

what are trophic levels

the different levels of a food chain

in different food chains there are —— numbers of trophic levels

different

what is in each trophic level

1. producer

2. primary consumer they are herbivores

3. secondary consumers they are carnivores as they eat other animals

4. tertiary consumers they are also carnivores

why does only 10% of biomass get passed on each time

1. organims don’t eat every part of an organism eg. bones

2. bits that organisms eat some get egested as faeces

3. most of the nutrients that animals absorb used to release energy through respiration and so the biomass gets released as waste products, so when the organism ends up getting eaten it doesn’t pass on all the biomass that it’s consumed in its life as it’s been using it for everyday functions

why do bars get smaller as you go up the trophic levels

because everytime an organism is consumed by another and we move up a trophic level most of the biomass is either lost or used,

what do the bars in pyramids of biomass represent

each bar represents the total biomass of that species in the food chain

what is biomass

biomass refers to the organic material that comes from living organisms