| A | B |
|---|
| abiotic | nonliving |
| acid deposition | The falling of acids and acid-forming compounds from the atmosphere to the earth's surface. |
| acid rain | The falling of acids and acid-forming compounds from the atmosphere to the earth's surface. |
| aerobic respiration | Complex process that occurs in the cells of most living organisms, in which nutrient organic molecules such as glucose (C6H12O6) combine with oxygen (O2) and produce carbon dioxide (CO2), water (H2O), and energy. |
| anaerobic respiration | Form of cellular respiration in which some decomposers get the energy they need through the breakdown of glucose (or other nutrients) in the absence of oxygen. |
| aquatic | Pertaining to water. |
| aquatic life zone | Marine and freshwater portions of the biosphere. Examples include freshwater life zones (such as lakes and streams) and ocean or marine life zones (such as estuaries, coastlines, coral reefs, and the deep ocean). |
| asexual reproduction | Reproduction in which a mother cell divides to produce two identical daughter cells that are clones of the mother cell. This type of reproduction is common in single-celled organisms. |
| atmosphere | The whole mass of air surrounding the earth. |
| biome | Terrestrial regions inhabited by certain types of life, especially vegetation. Examples are various types of deserts, grasslands, and forests. |
| biodiversity | Variety of different species (species diversity), genetic variability among individuals within each species (genetic diversity), variety of ecosystems (ecological diversity), and functions such as energy flow and matter cycling needed for the survival of species and biological communities (functional diversity). |
| biogeochemical cycle | Natural processes that recycle nutrients in various chemical forms from the nonliving environment to living organisms and then back to the nonliving environment. Examples are the carbon, oxygen, nitrogen, phosphorus, sulfur, and hydrologic cycles. |
| biomass | Organic matter produced by plants and other photosynthetic producers; total dry weight of all living organisms that can be supported at each trophic level in a food chain or web; dry weight of all organic matter in plants and animals in an ecosystem; plant materials and animal wastes used as fuel. |
| biosphere | Zone of earth where life is found. It consists of parts of the atmosphere (the troposphere), hydrosphere (mostly surface water and groundwater), and lithosphere (mostly soil and surface rocks and sediments on the bottoms of oceans and other bodies of water) where life is found. Sometimes called the ecosphere. |
| biotic | Living organisms. |
| biotic potential | Maximum rate at which the population of a given species can increase when there are no limits on its rate of growth. |
| carbon cycle | Cyclic movement of carbon in different chemical forms from the environment to organisms and then back to the environment. |
| cell | Smallest living unit of an organism. Each cell is encased in an outer membrane or wall and contains genetic material (DNA) and other parts to perform its life function. |
| chemosynthesis | Process in which certain organisms (mostly specialized bacteria) extract inorganic compounds from their environment and convert them into organic nutrient compounds without the presence of sunlight. |
| community | Populations of all species living and interacting in an area at a particular time. |
| condensation nuclei | Tiny particles on which droplets of water vapor can collect. |
| consumer | Organism that cannot synthesize the organic nutrients it needs and gets its organic nutrients by feeding on the tissues of producers or of other consumers |
| primary consumers | herbivores |
| secondary consumers | carnivores |
| tertiary (higher-level) consumers | omnivores |
| detritus | Parts of dead organisms and cast-off fragments and wastes of living organisms. |
| decomposer | Organism that digests parts of dead organisms and cast-off fragments and wastes of living organisms by breaking down the complex organic molecules in those materials into simpler inorganic compounds and then absorbing the soluble nutrients. |
| detritivore | Consumer organism that feeds on detritus, parts of dead organisms, and cast-off fragments and wastes of living organisms. |
| detritus feeder | Organism that extracts nutrients from fragments of dead organisms and their cast-off parts and organic wastes. Examples are earthworms, termites, and crabs. |
| dissolved oxygen (DO) content | Amount of oxygen gas (O2) dissolved in a given volume of water at a particular temperature and pressure, often expressed as a concentration in parts of oxygen per million parts of water. |
| distribution | Area over which we can find a species. |
| ecological diversity | The variety of forests, deserts, grasslands, oceans, streams, lakes, and other biological communities interacting with one another and with their nonliving environment. |
| ecological efficiency | Percentage of energy transferred from one trophic level to another in a food chain or web. |
| ecology | Study of the interactions of living organisms with one another and with their nonliving environment of matter and energy; study of the structure and functions of nature. |
| ecosystem | Community of different species interacting with one another and with the chemical and physical factors making up its nonliving environment. |
| ecotone | Transitional zone in which one type of ecosystem tends to merge with another ecosystem. |
| edge effect | The existence of a greater number of species and a higher population density in a transition zone (ecotone) between two ecosystems than in either adjacent ecosystem. |
| eukaryotic cell | Cell containing a nucleus, a region of genetic material surrounded by a membrane. |
| food chain | Series of organisms in which each eats or decomposes the preceding one. |
| food web | Complex network of many interconnected food chains and feeding relationships. |
