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Section M: Ecology and Feeding Relationships (key terms (population = a…
Section M: Ecology and Feeding Relationships
key terms
population = a group of individuals of the same species living in the same area at the same time
habitat = the area where an individual lives
community = all of the populations living together and interacting in the same area at the same time
population size = the number of individuals of a species in a given area
ecosystem = a definable area comprising the community and their abiotic (non-living surroundings)
herbivores (primary consumers)= eat producers
carnivores (secondary and tertiary consumers)= eat animals
omnivores = eat producers and animals
consumers = get their energy by eating organic molecules. There are 1st, 2nd & 3rd consumers depending on where they are on the food chain
decomposers = bacteria and fungi that feed on dead organic matter (Saprotrophic nutrition)
producers = plants that make food by photosynthesis. they change energy in sunlight into stored chemical energy in organic molecules
quadrats
it's important to count all members of a population so biologists use sampling squares to estimate the size of a population
one method of sampling is to use quadrants
done randomly to avoid bias
a square frame of a certain size (a 0.5x0.5m wire suare)
these are placed randomly in the area to be sampled and the number of the target organism within the quadrat are counted
repeated a number of times...
to collect enough data for statistical analysis
the mean number of the organism per quadrat is determined
use a grid to randomly generate co-ordinates
different trophic levels
cabbage
rabbit
stoat
fox
producer
primary consumer & herbivore
secondary consumer & (carnivore)
tertiary consumer & carnivore
trophic level 1
trophic level 2
trophic level 3
trophic level 4
feeding level is called a trophic level
food webs
shows who eats what in a particular habitat
grass → vole → barn owl
food chains & webs show the flow of energy in habitats
they do not give any idea of how many organisms there are in a habitat
explaining why only about 10% of energy is transferred from one trophic level to the next
pyramids of number
the feeding relationships may be shown quantitatively by constructing pyramids
the producer is always at the bottom of the pyramid
the length of the bar is proportional to the number of the organism at each stage of the food chain (trophic level)
the pyramid of numbers show: the numbers of organisms at each stage of the food chain
take into consideration: shape → steps are the same height, order of organism, names of organisms, the width of the steps
