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the branch of biology that deals with the relations of organisms to one another and to their physical surroundings


the regions of the surface, atmosphere, and hydrosphere of the earth occupied by living organisms

biotic factor

living things in their ecological relations

abiotic factor

physical rather than biological; not derived from living organisms


all the inhabitants of a particular town, area, or country

biological community

all the interacting populations of different species that live in the same geographical location at the same time


a biological community of interacting organisms and their environment


a large naturally occurring community of flora and fauna occupying a major habitat


the natural home or environment of an animal, plant, or other organism


role, or position, of an organism in its environment


act of one organism feeding on another


close mutualistic, parasitistic, or commensal association between 2 or more species that live together


symbiotic relationship where both species benefit


symbiotic relationship in which one organism benefits and the other is neither helped nor harmed


symbiotic relationship where on organism benefits at the expense of another

individual - population - community - ecosystem - biome - biosphere

order from most specific to broadest

individual / organism

any unicellular or multicellular form (with the characteristics of living things)

population size

a number of organisms present in a given population at a given time

population density

number of individuals within a population per unit area

producer/consumer, predator/prey, parasite/host

3 main types of feeding relationships

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