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ecosytems, trophic levels, carbon, phosphorus, nitrogen cycles, etc.

All the organisms in a particular area make up a(n) _____.


According to the principle of competitive exclusion, two species cannot continue to occupy the same _____.

ecological niche

In terms of + (this member of a species pair benefits from the interaction), - (this member of a species pair is harmed by the interaction), and 0 (this member of a species pair is unaffected by the interaction), predation can be described as a _____ relationship.


The ecological relationship between termites and the wood-digesting protozoans that live in their gut is an example of _____.


During ecological succession, the species composition of a plant community _____.

changes gradually because each species responds differently to changes in environmental factors

The energy for nearly every organism in almost every ecosystem ultimately comes from _____.

the sun

An organism's "trophic level" refers to _____. (

what it eats

Consider this segment of a food web: Snails and grasshoppers eat pepper plants; spiders eat grasshoppers; shrews eat snails and spiders; owls eat shrews. The shrew occupies the trophic level(s) of _____.

secondary and tertiary consumers

What generally flows in one direction through an ecosystem, from producers up through each level of consumers, and is not recycled?


Which of the following ecosystems would probably have the highest primary productivity? Assume that we are comparing similar sizes of each ecosystem.

a tropical coral reef

Biogeochemical cycles are crucial to ecosystem function because _____.

nutrients and other life-sustaining molecules are in limited supply and must be continually recycled

An ecosystem is unlikely to be limited by the supply of _____ because it is obtained from the air.


The main cause of the recent increase in the amount of carbon dioxide in Earth's atmosphere is _____.

the burning of larger amounts of wood and fossil fuels


a population of organisms living close enough together for potential reaction

interspecific interactions

relationships with individuals of other species in the community

interspecific competition

when populations of two different species compete for the same limited resource


both benefit


one benefits, one is harmed


one benefits, one is harmed

parasitism (pathogens too)

one benefits, one is harmed


one benefits, one has no difference


(at bottom) the trophic level that supports all others, usually plants

primary consumers

eat the producers, herbivores

secondary consumers

eat the primary consumers (herbivores), small mammals

tertiary consumers

eat the secondary consumers, a little larger animal

quaternary consumers

(at top) eat the tertiary consumers, in terrestrial ecosystems

detritivores and decomposers

get energy from dead material (detritus)


dead material, feed detritivores and decomposers


breakdown of organic materials to inorganic ones

ecological succession

biological community change

primary succession

lifeless area with no soil

secondary succession

a disturbance destroyed an existing community, but left the soil intact


consists of all organisms in a community and the abiotic environment and the organisms interact

biogeochemical cycle

an ecosystem that includes biotic and abiotic components

abiotic reservoir


biotic reservoir


nitrogen fixation

performed by some bacteria, converts nitrogen to compound of nitrogen that can be used by plants

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