GLOSSARY

These are all AP Environmental Science terms you should know for the exam, so make flashcards or write down these words in a notebook, and study them any chance you get. Do whatever you have to do to commit them to memory before exam day! An example of the glossary is listed below. Review the attached flashcards for the complete APES glossary.

Chapter 4: The Living World: Ecosystems and Biodiversity

• 10% Rule—the rule that in a food chain, only about 10% of the energy is transferred from one level to the next

• abiotic—related to factors or things that are separate and independent from living things; nonliving

• abyssal zone—the deepest region of the ocean, marked by extremely cold temperatures and low levels of dissolved oxygen, but high levels of nutrients because of the decaying plant and animal matter that sinks down from the zones above

• ammonification—the production of ammonia or ammonium compounds in the decomposition of organic matter, especially through the action of bacteria

• anaerobic—without oxygen

• aquatic life zones—ecosystems in aqueous environments

• assimilation—the process in which plants absorb ammonium (NH3), ammonia ions (NH4+), and nitrate ions (NO3) through their roots

• autotrophs—producers; organisms that can produce their own organic compounds from inorganic compounds; they use energy from the Sun or from the oxidation of inorganic substances

• barrier island—a long, relatively narrow island running parallel to the mainland, built up by the action of waves and currents and serving to protect the coast from erosion by surf and tidal surges

• bathyal zone—the middle region of the ocean, characterized by less density of organisms because it does not receive enough light to support photosynthesis

• benthic zone—the surface and sub-surface layers of the river-, lake-, pond-, or streambed, characterized by very low temperatures and low oxygen levels

• biodiversity—the number and variety of organisms found within a specified geographic region, or ecosystem, or the variability among living organisms, including the variability within and between species and within and between ecosystems

• biogeochemical cycles—the complex cycles through which nutrients such as carbon, oxygen, nitrogen, phosphorus, sulfur, and water move through the environment

• biological extinction—true extermination of a species; no individuals of this species are left on the planet

• biomes—ecosystems based on land

• biotic—living or derived from living things

• chaparral—scrub forest or shrubland; a biome characterized by moderate precipitation, shallow or infertile soil, small trees with large, hard evergreen leaves, and spiny shrubs

• chemotrophs—autotrophic bacteria that use chemosynthesis to produce energy in anaerobic environments

• climax community—a stable, mature community in a successive series that has reached equilibrium after having evolved through stages and adapted to its environment

• combusted—burned

• commensalism—symbiotic relationship in which one organism benefits while the other is neither helped nor hurt

• commercial (economic) extinction—a few individuals exist but the effort needed to locate and harvest them is not worth the expense

• community—formed from populations of different species occupying the same geographic area

• competition—the relationship that exists when two individuals—of the same species or of different species—compete for resources in the same environment

• competitive exclusion—the process that occurs when two different species in a region compete and the better adapted species wins coniferous forest (taiga)—a biome characterized by moderate precipitation, acidic soil, and coniferous trees

• consumers—organisms that must obtain food energy from secondary sources, for example, by eating plant or animal matter

• coral reef—an erosion-resistant marine ridge or mound consisting chiefly of compacted coral together with algal material and biochemically deposited magnesium and calcium carbonates

• coastal zone—ocean zone consisting of the ocean water closest to land, usually defined as between the shore and the end of the continental shelf (the edge of the tectonic plate); characterized by abundant sunlight and oxygen

• cultural services—use of nature for science and education, therapeutic and recreational uses, and spiritual and cultural uses

• deciduous forest—a biome characterized by adequate precipitation, rich soil with high organic content, and hardwood trees

• decomposers—organisms that consume dead plant and animal material—the process of decomposition returns nutrients to the environment

• denitrification—the process by which specialized bacteria (mostly anaerobic bacteria) convert ammonia to NO3, NO2, and N2, which are released back into the atmosphere

• deserts—biomes characterized by extremely low precipitation, coarse sandy soil, and cactus and other low-water adapted plants

• detritivores—organisms that derive energy from consuming nonliving organic matter, such as dead animals or fallen leaves

• ecological extinction—the condition in which there are so few individuals of a species that the species can no longer perform its ecological function

• ecological succession—the transition in species composition of a biological community, often following ecological disturbance of the community; the establishment of a biological community in any area virtually barren of life

• economic extinction—see commercial extinction

• ecoregions—see ecozones

• ecosystem—a system of interconnected elements: a community of living organisms and its environment

• ecosystem services—benefits that humans receive from the ecosystems in nature when they function properly

• ecotones—regions where different biomes overlap

• ecozones (ecoregions)—smaller regions within ecosystems that share similar physical features

• edge effect—the condition in which there is greater species diversity and biological density at ecosystem boundaries than there is in the heart of ecological communities

• energy pyramid—the structure obtained if we organize the amount of energy contained in producers and consumers in an ecosystem by kilocalories per square meter, from largest to smallest

• epilimnion—the uppermost and thus the most oxygenated layer of freshwater

• estuary—the part of the wide lower course of a river where its current is met by the tides

• euphotic zone—the photic, upper layers of ocean water; the euphotic zone is the warmest region of ocean water and has the highest levels of dissolved oxygen eutrophication—warm water becoming overly enriched with minerals and nutrients to the point that excessive growth of algae and other phytoplankton occurs (an algal bloom)

• evaporation—conversion of a liquid into a gas (vapor)

• evolution—change in the genetic composition of a population during successive generations as a result of natural selection acting on the genetic variation among individuals and resulting in the development of new species

• evolutionary fitness—the better-adaptedness of individual organisms for their environment that allows them to live and reproduce, ensuring that their genes are part of their population’s next generation

• exchange pool—a site where a nutrient sits for only a short period of time

• extinction—the death of an entire species; permanent inactivity

• food chain—a succession of organisms in an ecological community that constitutes a continuation of food energy from one organism to another as each consumes a lower member and, in turn, is preyed upon by a higher member food web—a complex of interrelated food chains in an ecological community

• fundamental niche—the niche a species would have if there were no competition

• Gause’s principle—states that no two species can occupy the same niche at the same time, and that the species that is less fit to live in the environment will either relocate, die out, or occupy a smaller niche

• gene pool—the total genetic makeup of a population

• generalist—a species that has a broad niche, is highly adaptable, and can live in varied habitats

• genetic drift—the random fluctuations in the frequency of the appearance of a gene in a small, isolated population, presumably owing to chance, rather than natural selection

• grasslands—a biome characterized by moderate precipitation, rich soil, and sod-forming grasses

• Gross Primary Productivity—the amount of sugar that the plants produce in photosynthesis

• groundwater—any water that comes from below the ground (from wells or from aquifers) habitat—the area or environment where an organism or ecological community normally lives or occurs

• habitat fragmentation—when the size of an organism’s natural habitat is reduced, or when development occurs that isolates a habitat or part of one