Ch 3

• Atmosphere - Whole mass of air surrounding the earth. See stratosphere, troposphere. Compare biosphere, geosphere, hydrosphere.

• Troposphere - Innermost layer of the atmosphere. It contains about 75% of the mass of earth’s air and extends about 17 kilometers (11 miles) above sea level. Compare stratosphere.

• Stratosphere - Second layer of the atmosphere, containing the ozone layer, which filters out most of the sun’s harmful UV-light rays.
• Hydrosphere - Earth’s liquid water (oceans, lakes, other bodies of surface water, and underground water), frozen water (polar ice caps, glaciers, and ice in soil, known as permafrost), and water vapor in the atmosphere. See also hydrologic cycle. Compare atmosphere, biosphere, geosphere.

• Geosphere - Earth’s intensely hot core, thick mantle composed mostly of rock, and thin outer crust that contains most of the earth’s rock, soil, and sediment. Compare atmosphere, biosphere, hydrosphere.

• Biosphere - Zone of the 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. Compare atmosphere, geosphere, hydrosphere.

• Greenhouse effect


  Natural effect that releases heat in the atmosphere near the earth's surface
• Greenhouse effect


  • Water vapor, carbon dioxide, methane, and other gases in the lower atmosphere (troposphere) absorb some of the infrared radiation (heat) radiated by the earth's surface
  • Their molecules vibrate and transform the absorbed energy into longer-wavelength infrared radiation in the troposphere
  • If the atmospheric concentrations of these greenhouse gases increase and other natural processes do not remove them, the average temperature of the lower atmosphere will increase
• Greenhouse effect


  Compare climate change, global warming, greenhouse gases
• Trophic level - All organisms that are the same number of energy transfers away from the original source of energy (for example, sunlight) that enters an ecosystem. For example, all producers belong to the first trophic level and all herbivores belong to the second trophic level in a food chain or a food web. See food chain, food web.

• Producers/autotrophs - Organism that uses solar energy (green plants) or chemical energy (some bacteria) to manufacture the organic compounds it needs as nutrients from simple inorganic compounds obtained from its environment. Compare consumer, decomposer.

• Photosynthesis - Complex process in the cells of green plants that captures light energy and converts it to chemical bond energy.
• Consumers/Heterotrophs - 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; generally divided into primary consumers (herbivores), secondary consumers (carnivores), tertiary (higher-level) consumers, omnivores, and detritivores (decomposers and detritus feeders). In economics, one who uses economic goods. Compare producer.

• Primary consumers - Organism that feeds on some or all parts of plants or on other producers. Compare detritivore, omnivore, secondary consumer.

• Herbivores - ant-eating organism. Examples include deer, sheep, grasshoppers, and zooplankton. Compare carnivore, omnivore.

• Carnivores - Animal that feeds on other animals. Compare herbivore, omnivore.

• Secondary consumers - Organism that feeds only on primary consumers. Compare detritivore, omnivore, primary consumer.

• Tertiary - Animals that feeds on animal-eating animals. They feed at high trophic levels in food chains and webs. Examples are hawks, lions, bass, and sharks. Compare detritivore, primary consumer, secondary consumer.

• Omnivores - Animal that can use both plants and other animals as food sources. Examples include pigs, rats, cockroaches, and humans. Compare carnivore, herbivore.

• Decomposers - 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 some of the soluble nutrients, returning most of these chemicals to the soil and water for reuse by producers. Decomposers consist of various bacteria and fungi. Compare consumer, detritivore, producer.

• Detritus feeders/detritivores - Consumer organism that feeds on detritus, parts of dead organisms, and cast-off fragments and wastes of living organisms. Examples include earthworms, termites, and crabs. Compare decomposer.

• 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) to produce carbon dioxide (CO2), water (H2O), and energy. Compare photosynthesis.

• Soil - Complex mixture of inorganic minerals (clay, silt, pebbles, and sand), decaying organic matter, water, air, and living organisms.

• Food chain - Series of organisms in which each eats or decomposes the preceding one. Compare food web.

• Pyramid of energy flow - Diagram representing the flow of energy through each trophic level in a food chain or food web. With each energy transfer, only a small part (typically 10%) of the usable energy entering one trophic level is transferred to the organisms at the next trophic level.

• 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.
• Food web - Complex network of many interconnected food chains and feeding relationships. Compare food chain.

• Gross primary productivity (GPP) - Rate at which an ecosystem’s producers capture and store a given amount of chemical energy as biomass in a given length of time. Compare net primary productivity.

• Net primary productivity (NPP) - rate at which all the plants in an ecosystem produce net useful chemical energy; equal to the difference between the rate at which the plants in an ecosystem produce useful chemical energy (gross primary productivity) and the rate at which they use some of that energy through cellular respiration.
• Nutrient cycles/nutrients - Natural process that recycles nutrients in various chemical forms from the nonliving environment to living organisms and then back to the nonliving environment.
• Hydrologic cycle/water cycle - Biogeochemical cycle that collects, purifies, and distributes the earth’s fixed supply of water from the environment to living organisms and then back to the environment.

• Surface runoff - Water flowing off the land into bodies of surface water.
• Aquifers - Porous, water-saturated layers of sand, gravel, or bedrock that can yield an economically significant amount of water.

• Groundwater - Water that sinks into the soil and is stored in slowly flowing and slowly renewed underground reservoirs called aquifers; underground water in the zone of saturation, below the water table. Compare runoff, surface water.

• Carbon cycle - Cyclic movement of carbon in different chemical forms from the environment to organisms and then back to the environment.

• Nitrogen cycle - Cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment.

• Phosphorus cycle - Cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment.