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the scientific study of interactions among organisms and between organisms and their environment, or surrounding.


the part of the earth's crust, waters, and atmosphere that supports life.


the process by which autotrophs use light energy to power chemical reactions that convert carbon dioxide and water into oxygen and energy-rich carbohydrates such as sugars and starches.


groups of individuals that belong to the same species and live in the same area.


assemblages of different populations that live together in a defined area.


a collection of all the organisms that live in a particular place together with their nonliving, or physical, environment.


a group of ecosystems that have the same climate and similar dominant communities.

abiotic factors

all of the living organisms that inhabit an environment.


the position or function of an organism in a community of plants and animals.


the natural environment of an organism


organisms that capture energy from sunlight or chemicals and use that energy to produce food.


organisms that rely on other organisms for their energy and food supply.

food chain

a series of steps in which organisms transfer energy by eating and being eaten.

food web

when the feeding relationships among the various organisms in an ecosystem form a network of complex interactions.

ecological pyramid

a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web.

pyramid of energy

a diagram that shows energy relationships between trophic levels in the form of calories

pyramid of numbers

a diagram that shows the relationship between numbers of organisms at different trophic levels.

pyramid of biomass

a diagram that shows the living mass at each trophic level in a food web or food chain.

nitrogen cycle

bacteria converts N2 gas into amonia; other bacteria converts it to amonia to nitrates (which are used by plants); plants turn nitrates into nitrogen containing compounds (usually proteins); animals eat plants and convert plant proteins to animal proteins; animal dies --> decomposers break down the nitrogen containing compounds and return them to N2 gas in the atmosphere.

carbon cycle

CO2 --> [plant (photosynthesis) --> animal eats plant] --> cellular respiration/death --> carbon is given back to the environment. [WHEN STUFF IS BURNED (LIKE FORESTS/FOSSIL FUELS) CARBON DIOXIDE IS ALSO RELEASED INTO THE ENVIRONMENT]


the passage of water through a plant from the roots through the vascular system to the atmosphere.


process by which water changes from a liquid into an atmospheric gas


characterized by an abundant accumulation of nutrients that support a dense growth of algae and other organisms, the decay of which depletes the shallow waters of oxygen in summer.

nutrient cycles

the cycle of biological and chemical elements and compounds in specific patterns through substances in an ecosystem; the uptake, use, release, and storage of nutrients by plants and their environments.


the tendency of a system, especially the physiological system of higher animals, to maintain internal stability, owing to the coordinated response of its parts to any situation or stimulus that would tend to disturb its normal condition or function.

kingdom eubacteria

are the true bacteria. Some are decomposers that are involved in the nitrogen cycle.


(plant like protists) produce carbohydrates through photosynthesis. They produce more oxygen then all of the other autotrophs put together.


heterotrophs and decomposers that are involved in breaking down of dead plant matter.


orderly, natural changes in species that take place in the community of an ecosystem.

primary succession

changes in the species distribution that occur on rock that has never supported plant life before.

climax community

a stable, mature community that undergoes little or no succession -the new trees (plants) that are coming up under the old trees are the same species as the old trees.

secondary succession

changes that occur in a place that has supported plant life previously (soil already present).


a relationship where there is a close and permanent relationship between organisms of different species.


a symbiotic relationship where one species is benefited and the other is neither harmed nor benefited.


a symbiotic relationship where both species benefit.


a symbiotic relationship where one organism is harmed and the other organism is benefited.


ecological interaction between two or more species that use the same limited resource such as food, light, and water.

predator-prey relationship

the cycle in populations between the predator and prey populations.


an organism that kills and feeds on that organism


the organism that is killed

linear growth

straight line growth, for every unit increase on the x axis, there is an equal increase in the value on the y axis.

logistic growth

an "S" shaped growth curve, where the population eventually levels off at the carrying capacity of the environment.

carrying capacity

the maximum, equilibrium number of organisms of a particular species that can be supported indefinitely in a given environment.

exponential growth

occurs in populations where the population grows at an increasing rate.

non biodegradable

incapable of decaying


capable of decaying through the action of living organisms

biological magnification

is the process whereby certain substances such as pesticides or heavy metals move up the food chain.


diversity among and within plant and animal species in an environment.

cellular respiration

process that releases energy by breaking down glucose and other food molecules in the presence of oxygen.


domain of unicellular prokaryotes that have cell walls containing peptidoglycans

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