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scientific study of interactions among organisms and between organisms and their environment


an individual living thing


a group of organisms of the same species populating a given area


all of the populations in an ecosystem


living and nonliving things in an environment, together with their interactions


part of Earth in which life exists including land, water, and air or atmosphere


the solid part of the earth consisting of the crust and outer mantle


all the water at and near the surface of the earth, 97% of which is in oceans


the mass of air surrounding the Earth


of or relating to living organisms


any nonliving component of an environment

limiting factor

anything that restricts the number of individuals in a population


a major biotic community characterized by the dominant forms of plant life and the prevailing climate


a vast, level, treeless plain in the arctic regions. The ground beneath the surface of the tundras is frozen even in summer


a flat grassland in tropical or subtropical regions

temperate deciduous forest

forest in a temperate region, characterized by trees that drop their leaves annually


A biome dominated by grasses and associated herbaceous plants


A type of biome characterized by low moisture levels and infrequent and unpredictable precipitation. Daily and seasonal temperatures fluctuate widely

tropical rain forest

biome near the equator with consistant warm temperatures, wet weather, and lush plant growth

coniferous forest

forest populated by cone-bearing evergreen trees; mostly found in northern latitudes


Thick, dense, thorny evergreen shrub found in Mediterranean climates


pertaining to water

population density

number of individuals per unit area

carrying capacity

largest number of individuals of a population that a given environment can support


animal that hunts and eats other animals


animal hunted or caught for food


the struggle between organisms to survive in a habitat with limited resources


the type of environment in which an organism or group normally lives


organism's role, or job, in its habitat

symbiotic relationship

an interaction between two or more species that live together in direct contact


symbiotic relationship in which one organism lives in or on another organism (the host) and consequently harms it


symbiotic relationship in which both species benefit from the relationship


symbiotic relationship in which one member of the association benefits and the other is neither helped nor harmed

ecological succession

(ecology) the gradual and orderly process of change in an ecosystem brought about by the progressive replacement of one community by another until a stable climax is established

pioneer organism

the first organisms in an ecological succession that work the land


Symbiotic association between a fungus and a photosynthetic organism

climax community

a relatively stable long-lasting community reached in a successional series

primary succession

the series of changes that occur in an area where no soil exists

secondary succession

ecological succession following a disturbance that destroys a community without destroying the soil


an organism that makes its own food; also called a producer


an organism that gets its energy from sunlight


an organism that gets its energy from chemicals taken from the environment


organism that obtains energy from the foods it consumes; also called a consumer


organism that obtains energy by eating only plants


organism that obtains energy by eating animals


any animal that feeds on dead animals


a consumer that eats both plants and animals


an organism that gets energy by breaking down the remains of dead organisms or animal wastes and consuming or absorbing the nutrients

food chain

series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

food web

network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem


an organism that makes its own food; also called an autotroph

primary consumer

An organism that eats producers

secondary consumer

An organism that eats primary consumers

tertiary consumer

An organism that eats secondary consumers

pyramid of energy

an ecological pyramid that shows the energy flow through each trophic level in an ecosystem.

trophic level

feeding level in an ecosystem

water cycle

the continuous process by which water moves from Earth's surface to the atmosphere and back

carbon oxygen cycle

The movement of carbon and oxygen through the environment. Involves respiration, photosynthesis, decomposition, burning of oxygen, and plants and animals.

nitrogen cycle

the transfer of nitrogen from the atmosphere to the soil, to living organisms, and back to the atmosphere

renewable resources

resources that can be replaced in a relatively short period of time (food, solar energy, oxygen)

nonrenewable resources

resources that cannot be replaced in a short amount of time, people will use them up before they can be replaced by nature (fossil fuels, minerals, old growth forests)

Three R's

Reduce, reuse, recycle


The process of stripping the land of its trees

greenhouse effect

natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases

global warming

An increase in the average temperature of the earth's atmosphere (especially a sustained increase that causes climatic changes)

acid rain

rain containing acids that form in the atmosphere when industrial gas emissions (especially sulfur dioxide and nitrogen oxides) combine with water


Release of harmful materials into the environment

biological magnification

process by which pollutants become more concentrated in successive trophic levels of a food web

ozone depletion

caused by CFCs, methyl chloroform, carbon tetrachloride, halon, methyl bromide all of which attack stratospheric ozone. Negative effects of ozone depletion include increased UV, skin cancer, cataracts, and decreased plant growth.


the diversity of plant and animal life in a particular habitat (or in the world as a whole)

invasive species

species that enter new ecosystems and multiply, harming native species and their habitats


practice of harvesting or hunting to such a degree that remaining individuals may not be able to replenish the population


the preservation and careful management of the environment and of natural resources

thermal pollution

harm to lakes and rivers resulting from the release of excessive waste heat into them


air pollution by a mixture of smoke and fog, it makes a grey/brown haze


The process by which wind, water, ice, or gravity transports soil and sediment from one location to another


alternatives that must be given up when one is chosen over another

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