Ecosystems

food chain

This is a sequence of feeding interactions between organism in a given habitat

producer

First organism in the food chain it makes its food using photosynthesis eg grass

primary consumer

This is the second organism it eats the primary producer and so is a herbivore eg a rabbit

the secondary consumer

This eats the primary consumer and is therefore a carnivore eg a bird of pray

tertiary consumer

These are again carnivores eg a fox in this case the top predator

decomposer

These are the final organism in the food chain these are microorganism that break down the remains of dead biological material eg fungi and bacteria

why are decomposers do key

They return all the nutrients to the ground where plant ( primary consumers )uses them.

food web

food web is a system of independent and interlocking food chains in a given habitat or larger ecosystem

trophic level

describes the position of an organism in a food chain or web and describes its feeding relationships with other organisms

what are the 3 ways of illustrating how components in an ecosystem interact

pyramids of number

pyramids of biomass

pyramids of energy

pyramid of numbers

pyramid of numbers shows us how many organism there are at each trophic level in a food chain

what is a limitation of numbers

It doesn’t give an accurate representation of a food chain for example there could be very few trees however because there such massive organism many aphids and caterpillars can live one one tree

pyramid of biomass

pyramid of biomass shows the amount of dry biomass at each trophic level in a food chain

why do you have to use dry biomass

as it is more accurate to use than wet biomass as wet biomass is affected by water uptake and loss where as dry is more constant and wont vary depending on time of day and conditions right now.

limitation related to time

calculating dry biomass is time consuming as you have to take samples and get rid of all water content

limitation in sampling

biomass pyramids only show data at one point in time in one sample. eg at this point in time there might be more of one species than another however this could fluctuate. also a sample might not be representative of hole area eg more of species A than B in sample however in real life actually more of B in total

pyramids of energy

These represent the total energy stores of the organism at each trophic level in a food chain.

why isnt all the energy pass on

1. some is lost in waste products

2. used to keep warm

3. not all of the species can be eaten so not all energy passes on

4. some of that species body might be indigestible so energy from that part isn’t released

5. plants might be limited by how much they can photosynthesis