Ecosystems Flashcards
what does the term population mean?
all the organisms of a particular species found in an ecosystem at any one time
what does the term community mean?
the populations of all species found in a particular ecosystem at any one time from the community
what does the term ecosystem mean?
a distinct, self supporting system of organisms interacting with each other and the physical environment
what does the term habitat mean?
the places where the specific organisms live
what is the order of trophic levels?
- producers
- primary consumers
- secondary consumers
- tertiary consumers
- decomposers
what should every habitat provide?
- food
- water
- shelter
- space
what are producers?
organisms that produce their own food from the sun (eg. plants photosynthesising)
what are primary consumers?
animals that eat plants; herbivore
what are secondary consumers?
animals that eat primary consumers; omnivore
what are tertiary consumers?
animals that eat secondary consumers; carnivore
what are decomposers?
when any of these organisms die they are broken down by decomposers- fungi and bacteria
what is a food chain?
a food chain shows how energy is passed on from one organism to another. The original source of energy is the sun
what is a food web?
a food web links several animals within a habitat showing what consumes what and what is consumed by what
what are pyramids of number?
pyramids of number show show the number of organisms in a food chain at each trophic level. They usually show that the number of organisms at each trophic level gets smaller towards the top.
what are pyramids of biomass?
pyramids of biomass are a more accurate indication of how much energy is passed on at each trophic level. Biomass is the mass of living material in each organism multiplied by the total number of organisms in that trophic level
what are pyramids of energy?
shows how much energy gets transferred from one trophic level to another
why is the biomass in each trophic level always less than the trophic level below?
because biomass is a measure of the amount of food available. When animals eat, only a small proportion of their food is converted into new tissue, which is the food for the next trophic level.
in what ways is the available energy to an organism predominantly used?
- energy released by respiration is used for movement and other life processes, and is eventually lost as heat to the surrounding
- energy is lost in waste materials, such as faeces
when can energy be passed onto the next trophic level?
if the energy of respiration is used to produce new cells (growth) or used to create offspring it remains fixed in the animal or plant and can be passed onto the next trophic level
why is only about 10% of energy passed onto the next trophic level?
- some parts of food aren’t eaten by organisms (eg. bones and roots) so not all energy is taken in
- lots of energy taken in is used by that organism for staying alive (eg. respiration)
- most energy is eventually lost to the surrounding as heat
- only around 10% of total energy available becomes biomass (stored or used for growth)
how can quadrants be used to estimate population size of an organism in two different areas?
- place about a 1m² quadrat on the ground and count all the organisms within it
- multiply the number of organisms, by the total area m² of the habitat to find an estimate
- you can do this in a different area, to compare the population sizes
how can quadrats be used to sample the distribution of organisms in their habitats?
- a sample square is taken at random
- the population of organisms in that square is taken
- this can be repeated in several different areas
- compare results to see which areas are densely populated and which are not
what are the stages of the carbon cycle?
there’s only a fixed amount of carbon in the world, so it’s constantly recycled via the carbon cycle:
- respiration is carried out by animals and plants to release energy from glucose, this means carbon is produced
- plants use carbon during photsynthesis
- decomposition happens when an animal dies, it is then eaten by a decomposer which releases the carbon in it back into the atmosphere
- combustion is burning, if something with carbon is burnt it will release it into the atmosphere (tree, fossil fuel)
what is decomposition?
where living things are broken down by bacteria and fungi when they die