 | Term | Definition |
| |
weather |
condition of Earth's atmosphere at a particular time and place |
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climate |
average, year-after-year conditions of temperature and precipitation in a particular region |
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greenhouse effect |
natural situation in which heat is retained in Earth's atmosphere by carbon dioxide, methane, water vapor, and other gases |
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polar zone |
cold climate zone where the sun's rays strke Earth at a very low angle |
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temperate zone |
moderate climate zone between the polar zones and the tropics |
| |
tropical zone |
warm climate zone that receives direct or nearly direct sunlight year round |
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biotic factor |
biological influence on organisms within an ecosystem |
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abiotic factor |
physical, or nonliving, factor that shapes an ecosystem |
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habitat |
the area where an organism lives, including the biotic and abiotic factors that affect it |
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niche |
full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions |
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resource |
any necessity of life, such as water, nutrients, light, food, or space |
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competitive exclusion principle |
ecological rule stating that no two species can occupy the same exact niche in the same habitat at the same time |
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predation |
interaction in which one organism captures and feeds on another organism |
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symbiosis |
relationship in which two species live closely together |
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mutualism |
symbiotic relationship in which both species benefit from the relationship |
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commensalism |
symbiotic relationship in which one member of the association benefits and the other is neither helped nor harmed |
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parasitism |
symbiotic relationship in which one organism lives in or on another organism (the host) and consequently harms it |
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ecological succession |
gradual change in living communities that follows a disturbance |
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primary succession |
succession that occurs on surfaces where no soil exists |
| |
pioneer species |
first species to populate an area during primary succession |
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secondary succession |
succession following a disturbance that destroys a community without destroying the soil |
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biome |
group of ecosystems that have the same climate and dominant communities |
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tolerance |
organism's capacity to grow or thrive when subjected to an unfavorable environmental factor |
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microclimate |
climate within a small are athat differs significantly from the climate of the surrounding area |
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canopy |
dense covering formed by the leafy tops of tall rain forest trees |
| |
understory |
layer in a rain forest formed by shorter trees and vines |
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deciduous |
term used to refer to a tree that sheds its leaves during a particular season each year |
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coniferous |
term used to refer to trees that produce seed-bearing cones and have thin leaves shaped like needles |
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humus |
material formed from decaying leaves and other organic matter |
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taiga |
biome in which the winters are cold but summers are mild enough to allow the ground to thaw |
| |
permafrost |
layer of permanently frozen subsoil in the tundra |
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autotroph |
organism that can capture energy from sunlight or chemicals and use it to produce is own food from inorganic compounds; also called a producer |
| |
producer |
organism that can capture energy from sunlight or chemicals and use it to produce food from inorganic compounds; also called an autotroph |
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photosynthesis |
process by which plants and some other organisms use light energy to convert water and carbon dioxide into oxygen and high-energy carbohydrates such as sugars and starches |
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chemosynthesis |
process by which some organisms, such as certain bacteria, use chemical energy to produce carbohydrates |
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heterotroph |
organism that obtains energy from the foods it comsumes; also called a consumer |
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consumer |
organism that relies on other organisms for its energy and food supply; also called a heterotroph |
| |
herbivore |
organism that obtains energy by eating only plants |
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carnivore |
organism that obtains energy by eating animals |
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omnivore |
organism that obtains energy by eating both plants and animals |
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detritivore |
organism that feeds on plant and animal remains and other dead matter |
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decomposer |
organism that breaks down and obtains energy from dead organic matter |
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food chain |
series of steps in an ecosystem in which organisms transfer energy by eating and being eaten |
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food web |
network of complex interactions formed by the feeding relationships among the various organisms in an ecosystem |
| |
trophic level |
step in a food chain or food web |
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ecological pyramid |
diagram that shows the relative amounts of energy or matter within each trophic level in a food chain or food web |
| |
biomass |
total amount of living tissue within a given trophic level |
