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a living thing


a group of living things of the same species that live in the same area


all of the populations that live and interact in an area


a community and its abiotic environment


non-living factors like air, water, and soil




the part of the Earth where life exists

primary consumer

herbivore; eats plants


makes food from sun; mostly plants, but some algae and bacteria


eats animals; terciary or secondary consumer


eats animals and plants; terciary or secondary consumer


breaks down dead organisms and turns them into soil; they are nature's recyclers


when something stays frozen all the time

carrying capacity

the largest population that an environment can support over a long period of time

limiting factor

scarce food, water, etc; when the population is greater than the carrying capacity, limiting factors will cause the population to shrink; due to limited resources, organisms sompete with each other, across and within species


when two species live closely together


when both organisms benefit in symbiosis


when one organism benefits and one is unaffected in symbiosis


when one organism benefits (a parasite) and one is harmed (a host) in symbiosis


a long-term change that takes place in two species because of close interactions with one another

climax community

a stable, mature community that undergoes little or no change in species over time


rain, sleet, etc; part of the water cycle


also known as transpiration; when liquid turns to vapor; part of the water cycle


when vapor turns to liquid; part of the water cycle


when carbon dioxide turns to carbohydrate; part of the carbon cycle


the breaking down of plant water by fungus and bacteria further add carbon to the environment


a geographic area characterized by certain types of plant and animal communities

temperate deciduous forest

has plenty of rain; big seasonal differences; trees lose their leaves in the winter to conserve water; diverse plant and animal life

coniferous forest

less seasonal differences than temperate forest; evergreen and needle trees; less diverse plant and animal life; few plants on the ground

tropical rain forest

much rain, little seasonal temperature variation; most diverse biome of all; poor soil


vegetation is mostly grass; many large plant-eating mammals live here; loads of large herbivores live here


hot, dry; plants have shallow root systems; animals are well-adapted (they store water, live at night, etc.)


has permafrost; little rain, but soil is soggy; grasses and small shrubs are common

water cycle

consists of precipitation, evaporation/ transpiration, and condensation

carbon cycle

consists of carbon dioxide in the air (which comes from animal respiration and the burning of fossil fuels) going through photosynthesis, respiration, and decomposition


when animals eat sugar and breathe out carbon dioxide as waste

nitrogen cycle

when nitrogen in the air (most air is nitrogen, but most living things can't use it) goes through nitrogen fixation (turns it to bacteria), and then the bacteria break down dead organisms and put nitrogen back into the air

energy pyramid

as you eat things nearer the top of the pyramid, you get less energy from it

food web vs. food chain

the food web is more accurate than the food chain because with the food web, you can see multiple animals/plants that eat or are eaten by another, while the food chain just shows one organism eats one more, which eats another, which eats another, and so on

primary succession

when things start to live where there was previously no life; consists of pioneer species adding levels of soil, moss growing and dyingonce the soil is deep enough, the dead moss adding soil, ferns replacing the moss, ferns are replaced by grasses, and when the soil is thick enough, small trees and eventually forests grow

pioneer species

example: lichens need little or no soil, but as they die, they add to the soil level

secondary succession

occurs when an existing community is destroyed by a natural disaster, or if a farmer stops growing crops (the difference is that soil already exists and the original community regrows); consists of grassy weeds growing, thicker weeds and more bushes grow, small needle trees grow, and then hardwoods grow

pond succession

consists of weeds growing in the water, and as they die, soil is added (eventually the pond fills up); the pond becoming a wetland full of grasses and weeds; shallow rooted trees, such as pines, grow; hardwood trees, like oaks, grow slowly but taller, and eventually shade out the pine trees and form a hardwood forest (which is the most common climax community in PA)


an animal or other organism that feeds on dead organic matter

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