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502 terms

APES all vocab

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affluenza
Unsustainable addiction to overconsumption and materialism exhibited in the lifestyles of affluent consumers in the United States and other developed countries.
agricultural revolution
Gradual shift from small, mobile hunting and gathering bands to settled agricultural communities in which people survived by learning how to breed and raise wild animals and to cultivate wild plants near where they lived. It began 10,000[[endash]]12,000 years ago. Compare environmental revolution, hunter[[endash]]gatherers, industrial[[endash]]medical revolution, information and globalization revolution.
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).
common-property resource
Resource that people normally are free to use; each user can deplete or degrade the available supply. Most are renewable and owned by no one. Examples are clean air, fish in parts of the ocean not under the control of a coastal country, migratory birds, gases of the lower atmosphere, and the ozone content of the upper atmosphere (stratosphere). See tragedy of the commons.
conservation
Sensible and careful use of natural resources by humans. People with this view are called conservationists.
conservationist
Person concerned with using natural areas and wildlife in ways that sustain them for current and future generations of humans and other forms of life. Compare conservation biologist, ecologist, environmentalist, environmental scientist, preservationist, restorationist.
developed country
Country that is highly industrialized and has a high per capita GNP. Compare developing country.
developing country
Country that has low to moderate industrialization and low to moderate per capita GNP. Most are located in Africa, Asia, and Latin America. Compare developed country.
doubling time
The time it takes (usually in years) for the quantity of something growing exponentially to double. It can be calculated by dividing the annual percentage growth rate into 70.
durability
Ability of earth's various systems, including human cultural systems and economies, to survive and adapt to changing environmental conditions indefinitely. This is another name for sustainability.
earth-centered environmental worldview
See environmental wisdom worldview.
ecological footprint
Amount of biologically productive land and water needed to supply each person or population with the renewable resources they use and to absorb or dispose of the wastes from such resource use. It measures the average environmental impact of individuals or populations in different countries and areas.
ecologist
Biological scientist who studies relationships between living organisms and their environment. Compare conservation biologist, conservationist, environmentalist, environmental scientist.
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.
economic development
Improvement of living standards by economic growth. Compare economic growth, environmentally sustainable economic development.
economic growth
Increase in the capacity to provide people with goods and services produced by an economy; an increase in gross domestic product (GDP). Compare economic development, environmentally sustainable economic development, sustainable economic development. See gross domestic product.
environment
All external conditions and factors, living and nonliving (chemicals and energy), that affect an organism or other specified system during its lifetime.
environmental degradation
Depletion or destruction of a potentially renewable resource such as soil, grassland, forest, or wildlife that is used faster than it is naturally replenished. If such use continues, the resource becomes nonrenewable (on a human time scale) or nonexistent (extinct). See also sustainable yield.
environmental ethics
Human beliefs about what is right or wrong environmental behavior.
environmental movement
Efforts by citizens at the grassroots level to demand that political leaders enact laws and develop policies to curtail pollution, clean up polluted environments, and protect pristine areas and species from environmental degradation.
environmental revolution
Cultural change involving halting population growth and altering lifestyles, political and economic systems, and the way we treat the environment so that we can help sustain the earth for ourselves and other species. This involves working with the rest of nature by learning more about how nature sustains itself. See environmental wisdom worldview. Compare agricultural revolution, hunter-gatherers, industrial-medical hunter[[endash]]gatherers, industrial[[endash]]medical revolution, information and globalization revolution.
environmental science
an interdisciplinary study that uses information from the physical sciences and social sciences tolerant how the earth works, how we interact with the earth, and how to deal with environmental problems.
environmental scientist
Scientist who uses information from the physical sciences and social sciences to understand how the earth works, learn how humans interact with the earth, and develop solutions to environmental problems. Compare conservation biologist, conservationist, ecologist, preservationist, restorationist.
environmental wisdom worldview
Beliefs that (1) nature exists for all the earth's species and we are not in charge of the earth; (2) resources are limited, should not be wasted, and are not all for us; (3) we should encourage earth-sustaining forms of economic growth and discourage earth-degrading forms of economic growth; and (4) our success depends on learning how the earth sustains itself and integrating such lessons from nature into the ways we think and act. Compare frontier environmental worldview, planetary management worldview, spaceship-earth worldview, stewardship worldview.
environmental worldview
How people think the world works, what they think their role in the world should be, and what they believe is right and wrong environmental behavior (environmental ethics).
environmentalism
A social movement dedicated to protecting the earth's life support systems for us and other species.
environmentalist
Person who is concerned about the impact of people on environmental quality and believe that some human actions are degrading parts of the earth's life-support systems for humans and many other forms of life. Compare conservation biologist, conservationist, ecologist, environmental scientist, preservationist, restorationist.
environmentally sustainable economic development
Development that encourages forms of economic growth that meet the basic needs of the current generations of humans and other species without preventing future generations of humans and other species from meeting their basic needs and discourages environmentally harmful and unsustainable forms of economic growth. It is the economic component of an environmentally sustainable society. Compare economic development, economic growth.
environmentally sustainable society
Society that satisfies the basic needs of its people without depleting or degrading its natural resources and thereby preventing current and future generations of humans and other species from meeting their basic needs.
EPA
U.S. Environmental Protection Agency; responsible for managing federal efforts to control air and water pollution, radiation and pesticide hazards, environmental research, hazardous waste, and solid-solid waste disposal.
exhaustible resource
See nonrenewable resource.
exponential growth
Growth in which some quantity, such as population size or economic output, increases at a constant rate per unit of time. An example is the growth sequence 2, 4, 8, 16, 32, 64 and so on; when the increase in quantity over time is plotted, this type of growth yields a curve shaped like the letter J. Compare linear growth.
free-access resource
See common-property resource.
frontier environmental worldview
Viewing undeveloped land as a hostile wilderness to be conquered (cleared, planted) and exploited for its resources as quickly as possible. Compare environmental wisdom worldview, planetary management worldview, spaceship-earth worldview.
globalization
Broad process of global social, economic, and environmental change that leads to an increasingly integrated world. See information and globalization revolution.
gross domestic product (GDP)
Annual market value of all goods and services produced by all firms and organizations, foreign and domestic, operating within a country.
human-centered environmental worldviews
Humans are the planet's most important species and should become managers or stewards of the earth. See planetary management worldview, stewardship worldview.
hunter[[endash]]gatherers
People who get their food by gathering edible wild plants and other materials and by hunting wild animals and fish. Compare agricultural revolution, environmental revolution, industrial[[endash]]medical revolution, information and globalization revolution.
industrial[[endash]]medical revolution
Use of new sources of energy from fossil fuels and later from nuclear fuels, and use of new technologies, to grow food and manufacture products. Compare agricultural revolution, environmental revolution, hunter[[endash]]gatherers, information and globalization revolution.
information and globalization revolution
Use of new technologies such as the telephone, radio, television, computers, the Internet, automated databases, and remote sensing satellites to enable people to have increasingly rapid access to much more information on a global scale. Compare agricultural revolution, environmental revolution, hunter[[endash]]gatherers, industrial[[endash]]medical revolution.
input pollution control
See pollution prevention.
LDC
See developing country.
less developed country (LDC)
See developing country.
maximum sustainable yield
See sustainable yield.
MDC
See developed country.
more developed country (MDC)
See developed country.
multiple use
Use of an ecosystem such as a forest for a variety of purposes such as timber harvesting, wildlife habitat, watershed protection, and recreation. Compare sustainable yield.
natural capital
See natural resources.
nonpoint source
Large or dispersed land areas such as crop fields, streets, and lawns that discharge pollutants into the environment over a large area. Compare point source.
nonrenewable resource
Resource that exists in a fixed amount (stock) in various places in the earth's crust and has the potential for renewal by geological, physical, and chemical processes taking place over hundreds of millions to billions of years. Examples are copper, aluminum, coal, and oil. We classify these resources as exhaustible because we are extracting and using them at a much faster rate than they were formed. Compare renewable resource.
output pollution control
See pollution cleanup.
per capita ecological footprint
Amount of biologically productive land and water needed to supply each person or population with the renewable resources they use and to absorb or dispose of the wastes from such resource use. It measures the average environmental impact of individuals or populations in different countries and areas. Compare ecological footprint.
per capita GDP
Annual gross domestic product (GDP) of a country divided by its total population at mid-year midyear. It gives the average slice of the economic pie per person. Used to be called per capita GNP. See gross domestic product.
perpetual resource
An essentially inexhaustible resource on a human time scale. Solar energy is an example. Compare nonrenewable resource, renewable resource.
planetary management worldview
Beliefs that (1) as the planet's most important species, we are in charge of the earth; (2) we will not run out of resources because of our ability to develop and find new ones; (3) the potential for economic growth is essentially unlimited; and (4) our success depends on how well we manage the earth's life-support systems mostly for our own benefit. See spaceship-earth worldview. Compare environmental wisdom worldview, stewardship worldview.
point source
Single identifiable source that discharges pollutants into the environment. Examples are the smokestack of a power plant or an industrial plant, drainpipe of a meatpacking plant, chimney of a house, or exhaust pipe of an automobile. Compare nonpoint source.
pollutant
A particular chemical or form of energy that can adversely affect the health, survival, or activities of humans or other living organisms. See pollution.
pollution
An undesirable change in the physical, chemical, or biological characteristics of air, water, soil, or food that can adversely affect the health, survival, or activities of humans or other living organisms.
pollution cleanup
Device or process that removes or reduces the level of a pollutant after it has been produced or has entered the environment. Examples are automobile emission control devices and sewage treatment plants. Compare pollution prevention.
pollution prevention
Device or process that prevents a potential pollutant from forming or entering the environment or sharply reduces the amount entering the environment. Compare pollution cleanup.
poverty
Inability to meet basic needs for food, clothing, and shelter.
recycling
Collecting and reprocessing a resource so that it can be made into new products. An example is collecting aluminum cans, melting them down, and using the aluminum to make new cans or other aluminum products. Compare reuse.
renewable resource
Resource that can be replenished rapidly (hours to several decades) through natural processes. Examples are trees in forests, grasses in grasslands, wild animals, fresh surface water in lakes and streams, most groundwater, fresh air, and fertile soil. If such a resource is used faster than it is replenished, it can be depleted and converted into a nonrenewable resource. Compare nonrenewable resource and perpetual resource. See also environmental degradation.
resource
Anything obtained from the living and nonliving environment to meet human needs and wants. It can also be applied to other species.
reuse
Using a product over and over again in the same form. An example is collecting, washing, and refilling glass beverage bottles. Compare recycling.
rule of 70
Doubling time (in years) = 70/(percentage growth rate). See doubling time, exponential growth.
social capital
Positive force created when people with different views and values find common ground and work together to build understanding, trust, and informed shared visions of what their communities, states, nations, and the world could and should be. Compare natural capital.
solar capital
Solar energy from the sun reaching the earth. Compare natural resources.
sound science
Scientific data, models, theories, and laws that are widely accepted by scientists considered experts in the area of study. These results of science are very reliable. Compare frontier science, junk science.
stewardship worldview
Beliefs that (1) we are the planet's most important species but we have an ethical responsibility to care for the rest of nature; (2) we will probably not run out of resources but they should not be wasted; (3) we should encourage environmentally beneficial forms of economic growth and discourage environmentally harmful forms of economic growth; and (4) our success depends on how well we can manage the earth's life-support systems for our benefit and for the rest of nature. Compare environmental wisdom worldview, planetary management worldview, spaceship earth worldview.
sustainability
Ability of a system to survive for some specified (finite) time.
sustainable development
See environmentally sustainable economic development.
sustainable living
Taking no more potentially renewable resources from the natural world than can be replenished naturally and not overloading the capacity of the environment to cleanse and renew itself by natural processes.
sustainable yield (sustained yield)
Highest rate at which a potentially renewable resource can be used without reducing its available supply throughout the world or in a particular area. See also environmental degradation.
tragedy of the commons
Depletion or degradation of a potentially renewable resource to which people have free and unmanaged access. An example is the depletion of commercially desirable fish species in the open ocean beyond areas controlled by coastal countries. See common-property resource.
acid
See acidic solution.
acid solution
Any water solution that has more hydrogen ions (H+) than hydroxide ions (OH[[minus]]); any water solution with a pH less than 7. Compare basic solution, neutral solution.
acidic solution
Any water solution that has more hydrogen ions (H+) than hydroxide ions (OH-); any water solution with a pH less than 7. Compare basic solution, neutral solution.
alpha particle
Positively charged matter, consisting of two neutrons and two protons, that is emitted as a form of radioactivity from the nuclei of some radioisotopes. See also beta particle, gamma rays.
atom
Minute unit made of subatomic particles that is the basic building block of all chemical elements and thus all matter; the smallest unit of an element that can exist and still have the unique characteristics of that element. Compare ion, molecule.
atomic number
Number of protons in the nucleus of an atom. Compare mass number.
basic solution
Water solution with more hydroxide ions (OH[[minus]]) than hydrogen ions (H+); water solution with a pH greater than 7. Compare acid solution, neutral solution.
beta particle
Swiftly moving electron emitted by the nucleus of a radioactive isotope. See also alpha particle, gamma rays.
biodegradable
Capable of being broken down by decomposers.
biodegradable pollutant
Material that can be broken down into simpler substances (elements and compounds) by bacteria or other decomposers. Paper and most organic wastes such as animal manure are biodegradable but can take decades to biodegrade in modern landfills. Compare degradable pollutant, nondegradable pollutant, slowly degradable pollutant.
chain reaction
Multiple nuclear fissions, taking place within a certain mass of a fissionable isotope, that release an enormous amount of energy in a short time.
chemical
One of the millions of different elements and compounds found naturally and synthesized by humans. See compound, element.
chemical change
Interaction between chemicals in which there is a change in the chemical composition of the elements or compounds involved. Compare nuclear change, physical change.
chemical formula
Shorthand way to show the number of atoms (or ions) in the basic structural unit of a compound. Examples are H2O, NaCl, and C6H12O6.
chemical reaction
See chemical change.
chlorinated hydrocarbon
Organic compound made up of atoms of carbon, hydrogen, and chlorine. Examples are DDT and PCBs.
chromosome
A grouping of various genes and associated proteins in plant and animal cells that carry certain types of genetic information. See genes.
complex carbohydrates
Two or more monomers of simple sugars (such as glucose) linked together.
compound
Combination of atoms, or oppositely charged ions, of two or more different elements held together by attractive forces called chemical bonds. Compare element.
concentration
Amount of a chemical in a particular volume or weight of air, water, soil, or other medium.
consensus science
See sound science.
corrective feedback loop
See negative feedback loop.
critical mass
Amount of fissionable nuclei needed to sustain a nuclear fission chain reaction.
deductive reasoning
Using logic to arrive at a specific conclusion based on a generalization or premise. It goes from the general to the specific. Compare inductive reasoning.
degradable pollutant
Potentially polluting chemical that is broken down completely or reduced to acceptable levels by natural physical, chemical, and biological processes. Compare biodegradable pollutant, nondegradable pollutant, slowly degradable pollutant.
deuterium (D; hydrogen-2)
Isotope of the element hydrogen, with a nucleus containing one proton and one neutron and a mass number of 2.
DNA (deoxyribonucleic acid)
Large molecules in the cells of organisms that carry genetic information in living organisms.
electromagnetic radiation
Forms of kinetic energy traveling as electromagnetic waves. Examples are radio waves, TV waves, microwaves, infrared radiation, visible light, ultraviolet radiation, X rays, and gamma rays. Compare ionizing radiation, nonionizing radiation.
electron (e)
Tiny particle moving around outside the nucleus of an atom. Each electron has one unit of negative charge and almost no mass. Compare neutron, proton.
element
Chemical, such as hydrogen (H), iron (Fe), sodium (Na), carbon (C), nitrogen (N), or oxygen (O), whose distinctly different atoms serve as the basic building blocks of all matter. Two or more elements combine to form compounds that make up most of the world's matter. Compare compound.
energy
Capacity to do work by performing mechanical, physical, chemical, or electrical tasks or to cause a heat transfer between two objects at different temperatures.
energy efficiency
Percentage of the total energy input that does useful work and is not converted into low-quality, usually useless heat in an energy conversion system or process. See energy quality, net energy. Compare material efficiency.
energy productivity
See energy efficiency.
energy quality
Ability of a form of energy to do useful work. High-temperature heat and the chemical energy in fossil fuels and nuclear fuels are concentrated high-quality energy. Low-quality energy such as low-temperature heat is dispersed or diluted and cannot do much useful work. See high-quality energy, low-quality energy.
eukaryotic cell
Cell containing a nucleus, a region of genetic material surrounded by a membrane. Membranes also enclose several of the other internal parts found in a eukaryotic cell. Compare prokaryotic cell.
eukaryotic organism
Classification of cell structure in which the cell is surrounded by a membrane and has a distinct nucleus and several other internal parts. Most organisms consist of eukaryotic cells. Compare prokaryotic organism.
experiment
Procedure a scientist uses to study some phenomenon under known conditions. Scientists conduct some experiments in the laboratory and others in nature. The resulting scientific data or facts must be verified or confirmed by repeated observations and measurements, ideally by several different investigators.
feedback loop
Circuit of sensing, evaluating, and reacting to changes in environmental conditions as a result of information fed back into a system; it occurs when one change leads to some other change, which eventually reinforces or slows the original change. See negative feedback loop, positive feedback loop.
first law of thermodynamics
In any physical or chemical change, no detectable amount of energy is created or destroyed, but in these processes energy can be changed from one form to another; you cannot get more energy out of something than you put in; in terms of energy quantity, you cannot get something for nothing (there is no free lunch). This law does not apply to nuclear changes, in which energy can be produced from small amounts of matter. See second law of thermodynamics.
flows
See throughputs.
frontier science
Preliminary scientific data, hypotheses, and models that have not been widely tested and accepted. Compare junk science, sound science.
gamma rays
A form of ionizing electromagnetic radiation with a high energy content emitted by some radioisotopes. They readily penetrate body tissues. See also alpha particle, beta particle.
genes
Coded units of information about specific traits that are passed on from parents to offspring during reproduction. They consist of segments of DNA molecules found in chromosomes.
half-life
Time needed for one-half of the nuclei in a radioisotope to emit its radiation. Each radioisotope has a characteristic half-life, which may range from a few millionths of a second to several billion years. See radioisotope.
heat
Total kinetic energy of all the randomly moving atoms, ions, or molecules within a given substance, excluding the overall motion of the whole object. Heat always flows spontaneously from a hot sample of matter to a colder sample of matter. This is one way to state the second law of thermodynamics. Compare temperature.
high-quality energy
Energy that is concentrated and has great ability to perform useful work. Examples are high-temperature heat and the energy in electricity, coal, oil, gasoline, sunlight, and nuclei of uranium-235. Compare low-quality energy.
high-quality matter
Matter that is concentrated and contains a high concentration of a useful resource. Compare low-quality matter.
high-throughput economy
The situation in most advanced industrialized countries, in which ever-increasing economic growth is sustained by maximizing the rate at which matter and energy resources are used, with little emphasis on pollution prevention, recycling, reuse, reduction of unnecessary waste, and other forms of resource conservation. Compare low-throughput economy, matter-recycling economy.
high-waste economy
See high-throughput economy.
hydrocarbon
Organic compound of hydrogen and carbon atoms. The simplest hydrocarbon is methane (CH4), the major component of natural gas.
inductive reasoning
Using observations and facts to arrive at generalizations or hypotheses. It goes from the specific to the general and is widely used in science. Compare deductive reasoning.
inorganic compounds
All compounds not classified as organic compounds. See organic compounds.
input
Matter, energy, or information entering a system. Compare output, throughput.
ion
Atom or group of atoms with one or more positive (+) or negative ([[minus]]) electrical charges. Compare atom, molecule.
ionizing radiation
Fast-moving alpha or beta particles or high-energy radiation (gamma rays) emitted by radioisotopes. They have enough energy to dislodge one or more electrons from atoms they hit, forming charged ions in tissue that can react with and damage living tissue. Compare nonionizing radiation.
isotopes
Two or more forms of a chemical element that have the same number of protons but different mass numbers because they have different numbers of neutrons in their nuclei.
junk science
Scientific results or hypotheses presented as sound science but not having undergone the rigors of the peer review process. Compare frontier science, sound science.
kinetic energy
Energy that matter has because of its mass and speed or velocity. Compare potential energy.
law of conservation of energy
See first law of thermodynamics.
law of conservation of matter
In any physical or chemical change, matter is neither created nor destroyed but merely changed from one form to another; in physical and chemical changes, existing atoms are rearranged into different spatial patterns (physical changes) or different combinations (chemical changes).
lipids
Chemically diverse group of large organic compounds that do not dissolve in water. Examples are fats and oils for storing energy, waxes for structure, and steroids for producing hormones.
low-quality energy
Energy that is dispersed and has little ability to do useful work. An example is low-temperature heat. Compare high-quality energy.
low-quality matter
Matter that is dilute or dispersed or contains a low concentration of a useful resource. Compare high-quality matter.
low-throughput economy
Economy based on working with nature by recycling and reusing discarded matter, preventing pollution, conserving matter and energy resources by reducing unnecessary waste and use, not degrading renewable resources, building things that are easy to recycle, reuse, and repair, not allowing population size to exceed the carrying capacity of the environment, and preserving biodiversity and ecological integrity. See environmental worldview. Compare high-throughput economy, matter-recycling economy.
low-waste economy
See low-throughput economy.
mass
The amount of material in an object.
mass number
Sum of the number of neutrons (n) and the number of protons (p) in the nucleus of an atom. It gives the approximate mass of that atom. Compare atomic number.
material efficiency
Total amount of material needed to produce each unit of goods or services. Also called resource productivity. Compare energy efficiency.
matter
Anything that has mass (the amount of material in an object) and takes up space. On the earth, where gravity is present, we weigh an object to determine its mass.
matter quality
Measure of how useful a matter resource is, based on its availability and concentration. See high-quality matter, low-quality matter.
matter-recycling economy
Economy that emphasizes recycling the maximum amount of all resources that can be recycled. The goal is to allow economic growth to continue without depleting matter resources and without producing excessive pollution and environmental degradation. Compare high-throughput economy, low-throughput economy.
mixture
Combination of one or more elements and compounds.
model
An approximate representation or simulation of a system being studied.
molecule
Combination of two or more atoms of the same chemical element (such as O2) or different chemical elements (such as H2O) held together by chemical bonds. Compare atom, ion.
natural law
See scientific law.
natural radioactive decay
Nuclear change in which unstable nuclei of atoms spontaneously shoot out particles (usually alpha or beta particles) or energy (gamma rays) at a fixed rate.
negative feedback loop
Situation in which a change in a certain direction provides information that causes a system to change less in that direction. Compare positive feedback loop.
neutral solution
Water solution containing an equal number of hydrogen ions (H+) and hydroxide ions (OH[[minus]]); water solution with a pH of 7. Compare acid solution, basic solution.
neutron (n)
Elementary particle in the nuclei of all atoms (except hydrogen-1). It has a relative mass of 1 and no electric charge. Compare electron, proton.
nondegradable pollutant
Material that is not broken down by natural processes. Examples are the toxic elements lead and mercury. Compare biodegradable pollutant, degradable pollutant, slowly degradable pollutant.
nonionizing radiation
Forms of radiant energy such as radio waves, microwaves, infrared light, and ordinary light that do not have enough energy to cause ionization of atoms in living tissue. Compare ionizing radiation.
nonpersistent pollutant
See degradable pollutant.
nuclear change
Process in which nuclei of certain isotopes spontaneously change, or are forced to change, into one or more different isotopes. The three principal types of nuclear change are natural radioactivity, nuclear fission, and nuclear fusion. Compare chemical change, physical change.
nuclear energy
Energy released when atomic nuclei undergo a nuclear reaction such as the spontaneous emission of radioactivity, nuclear fission, or nuclear fusion.
nuclear fission
Nuclear change in which the nuclei of certain isotopes with large mass numbers (such as uranium-235 and plutonium-239) are split apart into lighter nuclei when struck by a neutron. This process releases more neutrons and a large amount of energy. Compare nuclear fusion.
nucleic acids
Large polymer molecules made by linking hundreds to thousands of four types of monomers called nucleotides.
nucleus
Extremely tiny center of an atom, making up most of the atom's mass. It contains one or more positively charged protons and one or more neutrons with no electrical charge (except for a hydrogen-1 atom, which has one proton and no neutrons in its nucleus).
organic compounds
Compounds containing carbon atoms combined with each other and with atoms of one or more other elements such as hydrogen, oxygen, nitrogen, sulfur, phosphorus, chlorine, and fluorine. All other compounds are called inorganic compounds.
output
Matter, energy, or information leaving a system. Compare input, throughput.
paradigm shifts
Shifts in scientific thinking that occur when the majority of scientists in a field or related fields agree that a new explanation or theory is better than the old one.
parts per billion (ppb)
Number of parts of a chemical found in 1 billion parts of a particular gas, liquid, or solid.
parts per million (ppm)
Number of parts of a chemical found in 1 million parts of a particular gas, liquid, or solid.
parts per trillion (ppt)
Number of parts of a chemical found in 1 trillion parts of a particular gas, liquid, or solid.
persistence
How long a pollutant stays in the air, water, soil, or body. See also inertia.
persistent pollutant
See slowly degradable pollutant.
pH
Numeric value that indicates the relative acidity or alkalinity of a substance on a scale of 0 to 14, with the neutral point at 7. Acid solutions have pH values lower than 7, and basic or alkaline solutions have pH values greater than 7.
physical change
Process that alters one or more physical properties of an element or a compound without altering its chemical composition. Examples are changing the size and shape of a sample of matter (crushing ice and cutting aluminum foil) and changing a sample of matter from one physical state to another (boiling and freezing water). Compare chemical change, nuclear change.
positive feedback loop
Situation in which a change in a certain direction provides information that causes a system to change further in the same direction. Compare negative feedback loop.
potential energy
Energy stored in an object because of its position or the position of its parts. Compare kinetic energy.
ppb
See parts per billion.
ppm
See parts per million.
ppt
See parts per trillion.
prokaryotic cell
Cell that does not have a distinct nucleus. Other internal parts are also not enclosed by membranes. Compare eukaryotic cell.
prokaryotic organism
Classification of cell structure in which the cell contains no distinct nucleus or organelles enclosed by membranes. A prokaryotic cell is much simpler and usually much smaller than a eukaryotic cell. All bacteria are single-celled prokaryotic organisms. Compare eukaryotic organism.
proteins
Large polymer molecules formed by linking together long chains of monomers called amino acids.
proton (p)
Positively charged particle in the nuclei of all atoms. Each proton has a relative mass of 1 and a single positive charge. Compare electron, neutron.
radiation
Fast-moving particles (particulate radiation) or waves of energy (electromagnetic radiation). See alpha particle, beta particle, gamma rays.
radioactive decay
Change of a radioisotope to a different isotope by the emission of radioactivity.
radioactive isotope
See radioisotope.
radioactivity
Nuclear change in which unstable nuclei of atoms spontaneously shoot out "chunks" of mass, energy, or both at a fixed rate. The three principal types of radioactivity are gamma rays and fast-moving alpha particles and beta particles.
radioisotope
Isotope of an atom that spontaneously emits one or more types of radioactivity (alpha particles, beta particles, gamma rays).
resource productivity
See material efficiency.
science
Attempts to discover order in nature and use that knowledge to make predictions about what should happen in nature. See frontier science, scientific data, scientific hypothesis, scientific law, scientific methods, scientific model, scientific theory, sound science.
scientific data
Facts obtained by making observations and measurements. Compare scientific hypothesis, scientific law, scientific methods, scientific model, scientific theory.
scientific hypothesis
An educated guess that attempts to explain a scientific law or certain scientific observations. Compare scientific data, scientific law, scientific methods, scientific model, scientific theory.
scientific law
Description of what scientists find happening in nature repeatedly in the same way, without known exception. See first law of thermodynamics, law of conservation of matter, second law of thermodynamics. Compare scientific data, scientific hypothesis, scientific methods, scientific model, scientific theory.
scientific methods
The ways scientists gather data and formulate and test scientific hypotheses, models, theories, and laws. See scientific data, scientific hypothesis, scientific law, scientific model, scientific theory.
scientific model
A simulation of complex processes and systems. Many are mathematical models that are run and tested using computers.
scientific theory
A well-tested and widely accepted scientific hypothesis. Compare scientific data, scientific hypothesis, scientific law, scientific methods, scientific model.
second law of energy
See second law of thermodynamics.
second law of thermodynamics
In any conversion of heat energy to useful work, some of the initial energy input is always degraded to a lower-quality, more dispersed, less useful energy, usually low-temperature heat that flows into the environment; you cannot break even in terms of energy quality. See first law of thermodynamics.
slowly degradable pollutant
Material that is slowly broken down into simpler chemicals or reduced to acceptable levels by natural physical, chemical, and biological processes. Compare biodegradable pollutant, degradable pollutant, nondegradable pollutant.
solar energy
Direct radiant energy from the sun and a number of indirect forms of energy produced by the direct input. Principal indirect forms of solar energy include wind, falling and flowing water (hydropower), and biomass (solar energy converted into chemical energy stored in the chemical bonds of organic compounds in trees and other plants).
sound science
Scientific data, models, theories, and laws that are widely accepted by scientists considered experts in the area of study. These results of science are very reliable. Compare frontier science, junk science.
subatomic particles
Extremely small particles[[emdash]]electrons, protons, and neutrons[[emdash]]that make up the internal structure of atoms.
synergistic interaction
Interaction of two or more factors or processes so that the combined effect is greater than the sum of their separate effects.
synergy
See synergistic interaction.
system
A set of components that function and interact in some regular and theoretically predictable manner.
temperature
Measure of the average speed of motion of the atoms, ions, or molecules in a substance or combination of substances at a given moment. Compare heat.
throughput
Rate of flow of matter, energy, or information through a system. Compare input, output.
throwaway society
See high-throughput economy.
time delay
Time lag between the input of a stimulus into a system and the response to the stimulus.
abiotic
Nonliving. Compare biotic.
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. Compare photosynthesis.
albedo
Ability of a surface to reflect light.
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. Compare aerobic respiration.
aquatic
Pertaining to water. Compare terrestrial.
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).
atmosphere
The whole mass of air surrounding the earth. See stratosphere, troposphere.
autotroph
See producer.
bacteria
Prokaryotic, one-celled organisms. Some transmit diseases. Most act as decomposers and get the nutrients they need by breaking down complex organic compounds in the tissues of living or dead organisms into simpler inorganic nutrient compounds.
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.
biological community
See community.
biological diversity
See biodiversity.
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.
biome
Terrestrial regions inhabited by certain types of life, especially vegetation. Examples are various types of deserts, grasslands, and forests.
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. Compare abiotic.
calorie
Unit of energy; amount of energy needed to raise the temperature of 1 gram of water 1[[degree]]C (unit on Celsius temperature scale). See also kilocalorie.
carbon cycle
Cyclic movement of carbon in different chemical forms from the environment to organisms and then back to the environment.
carnivore
Animal that feeds on other animals. Compare herbivore, omnivore.
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. Organisms such as bacteria consist of only one cell, but most of the organisms we are familiar with contain many cells. See eukaryotic cell, prokaryotic cell.
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. Compare photosynthesis.
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; 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.
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. Producers return most of these chemicals to the soil and water for reuse. Decomposers consist of various bacteria and fungi. Compare consumer, detritivore, producer.
detritivore
Consumer organism that feeds on detritus, parts of dead organisms, and cast-off fragments and wastes of living organisms. The two principal types are detritus feeders and decomposers.
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. Compare decomposer.
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. See range.
ecological diversity
The variety of forests, deserts, grasslands, oceans, streams, lakes, and other biological communities interacting with one another and with their nonliving environment. See biodiversity. Compare functional diversity, genetic diversity, species diversity.
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.
ecosphere
See biosphere.
ecosystem
Community of different species interacting with one another and with the chemical and physical factors making up its nonliving environment.
fermentation
See anaerobic respiration.
food chain
Series of organisms in which each eats or decomposes the preceding one. Compare food web.
food web
Complex network of many interconnected food chains and feeding relationships. Compare food chain.
fossil fuel
Products of partial or complete decomposition of plants and animals that occur as crude oil, coal, natural gas, or heavy oils as a result of exposure to heat and pressure in he earth's crust over millions of years. See coal, crude oil, natural gas.
freshwater life zones
Aquatic systems where water with a dissolved salt concentration of less than 1% by volume accumulates on or flows through the surfaces of terrestrial biomes. Examples are standing (lentic) bodies of fresh water such as lakes, ponds, and inland wetlands and flowing (lotic) systems such as streams and rivers. Compare biome.
functional diversity
Biological and chemical processes or functions such as energy flow and matter cycling needed for the survival of species and biological communities. See biodiversity, ecological diversity, genetic diversity, species diversity.
genetic diversity
Variability in the genetic makeup among individuals within a single species. See biodiversity. Compare ecological diversity, functional diversity, species diversity.
gross primary productivity (GPP)
The 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.
habitat
Place or type of place where an organism or population of organisms lives. Compare ecological niche.
herbivore
Plant-eating organism. Examples are deer, sheep, grasshoppers, and zooplankton. Compare carnivore, omnivore.
heterotroph
See consumer.
HIPPO
Acronym for habitat destruction and fragmentation, invasive species, population growth, pollution, and overharvesting.
humus
Slightly soluble residue of undigested or partially decomposed organic material in topsoil. This material helps retain water and water-soluble nutrients, which can be taken up by plant roots.
hydrologic 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.
hydrosphere
The earth's liquid water (oceans, lakes, other bodies of surface water, and underground water), frozen water (polar ice caps, floating ice caps, and ice in soil, known as permafrost), and water vapor in the atmosphere. See also hydrologic cycle.
infiltration
Downward movement of water through soil.
kilocalorie (kcal)
Unit of energy equal to 1,000 calories. See calorie.
leaching
Process in which various chemicals in upper layers of soil are dissolved and carried to lower layers and, in some cases, to groundwater.
limiting factor
Single factor that limits the growth, abundance, or distribution of the population of a species in an ecosystem. See limiting factor principle.
limiting factor principle
Too much or too little of any abiotic factor can limit or prevent growth of a population of a species in an ecosystem, even if all other factors are at or near the optimum range of tolerance for the species.
lithosphere
Outer shell of the earth, composed of the crust and the rigid, outermost part of the mantle outside the asthenosphere; material found in earth's plates. See crust, mantle.
loams
Soils containing a mixture of clay, sand, silt, and humus. Good for growing most crops.
microorganisms
Organisms such as bacteria that are so small that they can be seen only by using a microscope.
natural greenhouse effect
Heat buildup in the troposphere because of the presence of certain gases, called greenhouse gases. Without this effect, the earth would be nearly as cold as Mars, and life as we know it could not exist. Compare global warming.
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. Compare gross primary productivity.
nitrogen cycle
Cyclic movement of nitrogen in different chemical forms from the environment to organisms and then back to the environment.
nitrogen fixation
Conversion of atmospheric nitrogen gas into forms useful to plants by lightning, bacteria, and cyanobacteria; it is part of the nitrogen cycle.
nutrient
Any food or element an organism must take in to live, grow, or reproduce.
nutrient cycle
See biogeochemical cycle.
omnivore
Animal that can use both plants and other animals as food sources. Examples are pigs, rats, cockroaches, and people. Compare carnivore, herbivore.
organism
Any form of life.
percolation
Passage of a liquid through the spaces of a porous material such as soil.
permeability
The degree to which underground rock and soil pores are interconnected and thus a measure of the degree to which water can flow freely from one pore to another. Compare porosity.
phosphorus cycle
Cyclic movement of phosphorus in different chemical forms from the environment to organisms and then back to the environment.
photosynthesis
Complex process that takes place in cells of green plants. Radiant energy from the sun is used to combine carbon dioxide (CO2) and water (H2O) to produce oxygen (O2) and carbohydrates (such as glucose, C6H12O6) and other nutrient molecules. Compare aerobic respiration, chemosynthesis.
population
Group of individual organisms of the same species living in a particular area.
porosity
Percentage of space in rock or soil occupied by voids, whether the voids are isolated or connected. Compare permeability.
precipitation
Water in the form of rain, sleet, hail, and snow that falls from the atmosphere onto the land and bodies of water.
primary consumer
Organism that feeds on all or part of plants (herbivore) or on other producers. Compare detritivore, omnivore, secondary consumer.
primary productivity
See gross primary productivity, net primary productivity.
producer
Organism that uses solar energy (green plant) 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.
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. Compare pyramid of biomass, pyramid of numbers.
range
See distribution.
range of tolerance
Range of chemical and physical conditions that must be maintained for populations of a particular species to stay alive and grow, develop, and function normally. See law of tolerance.
respiration
See aerobic respiration.
salinity
Amount of various salts dissolved in a given volume of water.
scavenger
Organism that feeds on dead organisms that were killed by other organisms or died naturally. Examples are vultures, flies, and crows. Compare detritivore.
secondary consumer
Organism that feeds only on primary consumers. Compare detritivore, omnivore, primary consumer.
soil
Complex mixture of inorganic minerals (clay, silt, pebbles, and sand), decaying organic matter, water, air, and living organisms.
soil horizons
Horizontal zones that make up a particular mature soil. Each horizon has a distinct texture and composition that vary with different types of soils. See soil profile.
soil permeability
Rate at which water and air move from upper to lower soil layers. Compare porosity.
soil porosity
See porosity.
soil profile
Cross-sectional view of the horizons in a soil. See soil horizon.
soil structure
How the particles that make up a soil are organized and clumped together. See also soil permeability, soil texture.
soil texture
Relative amounts of the different types and sizes of mineral particles in a sample of soil.
species
Group of organisms that resemble one another in appearance, behavior, chemical makeup and processes, and genetic structure. Organisms that reproduce sexually are classified as members of the same species only if they can actually or potentially interbreed with one another and produce fertile offspring.
species diversity
Number of different species and their relative abundances in a given area. See biodiversity. Compare ecological diversity, genetic diversity.
stratosphere
Second layer of the atmosphere, extending about 17[[endash]]48 kilometers (11[[endash]]30 miles) above the earth's surface. It contains small amounts of gaseous ozone (O3), which filters out about 95% of the incoming harmful ultraviolet (UV) radiation emitted by the sun. Compare troposphere.
sulfur cycle
Cyclic movement of sulfur in different chemical forms from the environment to organisms and then back to the environment.
terrestrial
Pertaining to land. Compare aquatic.
tertiary (higher-level) consumers
Animals that feed 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.
transpiration
Process in which water is absorbed by the root systems of plants, moves up through the plants, passes through pores (stomata) in their leaves or other parts, and evaporates into the atmosphere as water vapor.
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.
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.
water cycle
See hydrologic cycle.
weathering
Physical and chemical processes in which solid rock exposed at earth's surface is changed to separate solid particles and dissolved material, which can then be moved to another place as sediment. See erosion.
adaptation
Any genetically controlled structural, physiological, or behavioral characteristic that helps an organism survive and reproduce under a given set of environmental conditions. It usually results from a beneficial mutation. See biological evolution, differential reproduction, mutation, natural selection.
adaptive radiation
Process in which numerous new species evolve to fill vacant and new ecological niches in changed environments, usually after a mass extinction. Typically, this takes millions of years.
adaptive trait
See adaptation.
artificial selection
Process by which humans select one or more desirable genetic traits in the population of a plant or animal species and then use selective breeding to produce populations containing many individuals with the desired traits. Compare genetic engineering, natural selection.
background extinction
Normal extinction of various species as a result of changes in local environmental conditions. Compare mass depletion, mass extinction.
biological evolution
Change in the genetic makeup of a population of a species in successive generations. If continued long enough, it can lead to the formation of a new species. Note that populations[[emdash]]not individuals[[emdash]]evolve. See also adaptation, differential reproduction, natural selection, theory of evolution.
biopharming
Use of genetically engineered animals to act as biofactories for producing drugs, vaccines, antibodies, hormones, industrial chemicals such as plastics and detergents, and human body organs.
chemical evolution
Formation of the earth and its early crust and atmosphere, evolution of the biological molecules necessary for life, and evolution of systems of chemical reactions needed to produce the first living cells. These processes are believed to have occurred about 1 billion years before biological evolution. Compare biological evolution.
coevolution
Evolution in which two or more species interact and exert selective pressures on each other that can lead each species to undergo various adaptations. See evolution, natural selection.
differential reproduction
Phenomenon in which individuals with adaptive genetic traits produce more living offspring than do individuals without such traits. See natural selection.
domesticated species
Wild species tamed or genetically altered by crossbreeding for use by humans for food (cattle, sheep, and food crops), pets (dogs and cats), or enjoyment (animals in zoos and plants in gardens). Compare wild species.
ecological niche
Total way of life or role of a species in an ecosystem. It includes all physical, chemical, and biological conditions a species needs to live and reproduce in an ecosystem. See fundamental niche, realized niche.
endemic species
Species that is found in only one area. Such species are especially vulnerable to extinction.
evolution
See biological evolution.
extinction
Complete disappearance of a species from the earth. This happens when a species cannot adapt and successfully reproduce under new environmental conditions or when it evolves into one or more new species. Compare speciation. See also endangered species, mass depletion, mass extinction, threatened species.
fossils
Skeletons, bones, shells, body parts, leaves, seeds, or impressions of such items that provide recognizable evidence of organisms that lived long ago.
fundamental niche
The full potential range of the physical, chemical, and biological factors a species can use if there is no competition from other species. See ecological niche. Compare realized niche.
gene mutation
See mutation.
gene pool
The sum total of all genes found in the individuals of the population of a particular species.
gene splicing
See genetic engineering.
generalist species
Species with a broad ecological niche. They can live in many different places, eat a variety of foods, and tolerate a wide range of environmental conditions. Examples are flies, cockroaches, mice, rats, and human beings. Compare specialist species.
genetic adaptation
Changes in the genetic makeup of organisms of a species that allow the species to reproduce and gain a competitive advantage under changed environmental conditions. See differential reproduction, evolution, mutation, natural selection.
genetic engineering
Insertion of an alien gene into an organism to give it a beneficial genetic trait. Compare artificial selection, natural selection.
genetically modified organism (GMO)
Organism whose genetic makeup has been modified by genetic engineering.
geographic isolation
Separation of populations of a species for long times into different areas.
invertebrates
Animals that have no backbones. Compare vertebrates.
macroevolution
Long-term, large-scale evolutionary changes among groups of species. Compare microevolution.
mass depletion
Widespread, often global period during which extinction rates are higher than normal but not high enough to classify as a mass extinction. Compare background extinction, mass extinction.
mass extinction
A catastrophic, widespread, often global event in which major groups of species are wiped out over a short time compared with normal (background) extinctions. Compare background extinction, mass depletion.
microevolution
The small genetic changes a population undergoes. Compare macroevolution.
mutation
Random change in DNA molecules making up genes that can alter anatomy, physiology, or behavior in offspring. See mutagen.
natural rate of extinction
See background extinction.
natural selection
Process by which a particular beneficial gene (or set of genes) is reproduced in succeeding generations more than other genes. The result of natural selection is a population that contains a greater proportion of organisms better adapted to certain environmental conditions. See adaptation, biological evolution, differential reproduction, mutation.
niche
See ecological niche.
realized niche
Parts of the fundamental niche of a species that are actually used by that species. See ecological niche, fundamental niche.
recombinant DNA
DNA that has been altered to contain genes or portions of genes from organisms of different species.
reproductive isolation
Long-term geographic separation of members of a particular sexually reproducing species.
specialist species
Species with a narrow ecological niche. They may be able to live in only one type of habitat, tolerate only a narrow range of climatic and other environmental conditions, or use only one type or a few types of food. Compare generalist species.
speciation
Formation of two species from one species because of divergent natural selection in response to changes in environmental conditions; usually takes thousands of years. Compare extinction.
subpopulation
Individuals of a species that live in a habitat patch.
theory of evolution
Widely accepted scientific idea that all life forms developed from earlier life forms. Although this theory conflicts with the creation stories of many religions, it is the way biologists explain how life has changed over the past 3.6[[endash]]3.8 billion years and why it is so diverse today.
transgenic organisms
See genetically modified organisms (GMOs).
vertebrates
Animals that have backbones. Compare invertebrates.
wild species
Species found in the natural environment. Compare domesticated species.
altitude
See elevation.
arid
Dry. A desert or other area with an arid climate has little precipitation.
biome
Terrestrial regions inhabited by certain types of life, especially vegetation. Examples are various types of deserts, grasslands, and forests.
broadleaf deciduous plants
Plants such as oak and maple trees that survive drought and cold by shedding their leaves and becoming dormant. Compare broadleaf evergreen plants, coniferous evergreen plants.
broadleaf evergreen plants
Plants that keep most of their broad leaves year-round. Examples are the trees found in the canopies of tropical rain forests. Compare broadleaf deciduous plants, coniferous evergreen plants.
climate
Physical properties of the troposphere of an area based on analysis of its weather records over a long period (at least 30 years). The two main factors determining an area's climate are temperature, with its seasonal variations, and the amount and distribution of precipitation. Compare weather.
cold front
Leading edge of an advancing mass of cold air. Compare warm front.
coniferous evergreen plants
Cone-bearing plants (such as spruces, pines, and firs) that keep some of their narrow, pointed leaves (needles) all year. Compare broadleaf deciduous plants, broadleaf evergreen plants.
coniferous trees
Cone-bearing trees, mostly evergreens, that have needle-shaped or scalelike leaves. They produce wood known commercially as softwood. Compare deciduous plants.
deciduous plants
Trees, such as oaks and maples, and other plants that survive during dry seasons or cold seasons by shedding their leaves. Compare coniferous trees, succulent plants.
desert
Biome in which evaporation exceeds precipitation and the average amount of precipitation is less than 25 centimeters (10 inches) a year. Such areas have little vegetation or have widely spaced, mostly low vegetation. Compare forest, grassland.
elevation
Distance above sea level. Compare latitude.
evergreen plants
Plants that keep some of their leaves or needles throughout the year. Examples are ferns and cone-bearing trees (conifers) such as firs, spruces, pines, redwoods, and sequoias. Compare deciduous plants, succulent plants.
forest
Biome with enough average annual precipitation (at least 76 centimeters, or 30 inches) to support growth of various tree species and smaller forms of vegetation. Compare desert, grassland.
front
The boundary between two air masses with different temperatures and densities. See cold front, warm front.
grassland
Biome found in regions where moderate annual average precipitation (25[[endash]]76 centimeters, or 10[[endash]]30 inches) is enough to support the growth of grass and small plants but not enough to support large stands of trees. Compare desert, forest.
greenhouse effect
A natural effect that releases heat in the atmosphere (troposphere) near the earth's surface. Water vapor, carbon dioxide, ozone, and several other gases in the lower atmosphere (troposphere) absorb some of the infrared radiation (heat) radiated by the earth's surface. This causes their molecules to vibrate and transform the absorbed energy into longer-wavelength infrared radiation (heat) in the troposphere. If the atmospheric concentrations of these greenhouse gases rise and they are not removed by other natural processes, the average temperature of the lower atmosphere will increase gradually. Compare global warming. See also natural greenhouse effect.
greenhouse gases
Gases in the earth's lower atmosphere (troposphere) that cause the greenhouse effect. Examples are carbon dioxide, chlorofluorocarbons, ozone, methane, water vapor, and nitrous oxide.
high
An air mass with a high pressure. Compare low.
latitude
Distance from the equator. Compare altitude.
low
An air mass with a low pressure. Compare high.
monsoons
Periods of heavy rains experienced on continents lying north or south of warm oceans.
permafrost
Perennially frozen layer of the soil that forms when the water there freezes. It is found in arctic tundra.
prairies
See grasslands.
rain shadow effect
Low precipitation on the far side (leeward side) of a mountain when prevailing winds flow up and over a high mountain or range of high mountains. This creates semiarid and arid conditions on the leeward side of a high mountain range.
succulent plants
Plants, such as desert cacti, that survive in dry climates by having no leaves, thus reducing the loss of scarce water. They store water and use sunlight to produce the food they need in the thick, fleshy tissue of their green stems and branches. Compare deciduous plants, evergreen plants.
transpiration
Process in which water is absorbed by the root systems of plants, moves up through the plants, passes through pores (stomata) in their leaves or other parts, and evaporates into the atmosphere as water vapor.
warm front
The boundary between an advancing warm air mass and the cooler one it is replacing. Because warm air is less dense than cool air, an advancing warm front rises over a mass of cool air. Compare cold front.
weather
Short-term changes in the temperature, barometric pressure, humidity, precipitation, sunshine, cloud cover, wind direction and speed, and other conditions in the troposphere at a given place and time. Compare climate.
barrier islands
Long, thin, low offshore islands of sediment that generally run parallel to the shore along some coasts.
benthos
Bottom-dwelling organisms. Compare decomposer, nekton, plankton.
coastal wetland
Land along a coastline, extending inland from an estuary, that is covered with salt water all or part of the year. Examples are marshes, bays, lagoons, tidal flats, and mangrove swamps. Compare inland wetland.
coastal zone
Warm, nutrient-rich, shallow part of the ocean that extends from the high-tide mark on land to the edge of a shelflike extension of continental land masses known as the continental shelf. Compare open sea.
coral reef
Formation produced by massive colonies containing billions of tiny coral animals, called polyps, that secrete a stony substance (calcium carbonate) around themselves for protection. When the corals die, their empty outer skeletons form layers and cause the reef to grow. They are found in the coastal zones of warm tropical and subtropical oceans.
cultural eutrophication
Overnourishment of aquatic ecosystems with plant nutrients (mostly nitrates and phosphates) because of human activities such as agriculture, urbanization, and discharges from industrial plants and sewage treatment plants. See eutrophication.
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. Producers return most of these chemicals to the soil and water for reuse. Decomposers consist of various bacteria and fungi. Compare consumer, detritivore, producer.
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. Compare decomposer.
drainage basin
See watershed.
estuary
Partially enclosed coastal area at the mouth of a river where its fresh water, carrying fertile silt and runoff from the land, mixes with salty seawater.
euphotic zone
Upper layer of a body of water through which sunlight can penetrate and support photosynthesis.
eutrophic lake
Lake with a large or excessive supply of plant nutrients, mostly nitrates and phosphates. Compare mesotrophic lake, oligotrophic lake.
freshwater life zones
Aquatic systems where water with a dissolved salt concentration of less than 1% by volume accumulates on or flows through the surfaces of terrestrial biomes. Examples are standing (lentic) bodies of fresh water such as lakes, ponds, and inland wetlands and flowing (lotic) systems such as streams and rivers. Compare biome.
inland wetland
Land away from the coast, such as a swamp, marsh, or bog, that is covered all or part of the time with fresh water. Compare coastal wetland.
intertidal zone
The area of shoreline between low and high tides.
lake
Large natural body of standing fresh water formed when water from precipitation, land runoff, or groundwater flow fills a depression in the earth created by glaciation, earth movement, volcanic activity, or a giant meteorite. See eutrophic lake, mesotrophic lake, oligotrophic lake.
mangrove swamps
Swamps found on the coastlines in warm tropical climates. They are dominated by mangrove trees, any of about 55 species of trees and shrubs that can live partly submerged in the salty environment of coastal swamps.
mesotrophic lake
Lake with a moderate supply of plant nutrients. Compare eutrophic lake, oligotrophic lake.
nekton
Strongly swimming organisms found in aquatic systems. Compare benthos, plankton.
oligotrophic lake
Lake with a low supply of plant nutrients. Compare eutrophic lake, mesotrophic lake.
open sea
The part of an ocean that is beyond the continental shelf. Compare coastal zone.
phytoplankton
Small, drifting plants, mostly algae and bacteria, found in aquatic ecosystems. Compare plankton, zooplankton.
plankton
Small plant organisms (phytoplankton) and animal organisms (zooplankton) that float in aquatic ecosystems.
runoff
Fresh water from precipitation and melting ice that flows on the earth's surface into nearby streams, lakes, wetlands, and reservoirs. See reliable runoff, surface runoff, surface water. Compare groundwater.
surface water
Precipitation that does not infiltrate the ground or return to the atmosphere by evaporation or transpiration. See runoff. Compare groundwater.
ultraplankton
Photosynthetic bacteria no more than 2 micrometers wide.
upwelling
Movement of nutrient-rich bottom water to the ocean's surface. This can occur far from shore but usually occurs along certain steep coastal areas where the surface layer of ocean water is pushed away from shore and replaced by cold, nutrient-rich bottom water.
watershed
Land area that delivers water, sediment, and dissolved substances via small streams to a major stream (river).
wetland
Land that is covered all or part of the time with salt water or fresh water, excluding streams, lakes, and the open ocean. See coastal wetland, inland wetland.
zooplankton
Animal plankton. Small floating herbivores that feed on plant plankton (phytoplankton). Compare phytoplankton.
alien species
See nonnative species.
annual
Plant that grows, sets seed, and dies in one growing season. Compare perennial.
climax community
See mature community.
commensalism
An interaction between organisms of different species in which one type of organism benefits and the other type is neither helped nor harmed to any great degree. Compare mutualism.
competition
Two or more individual organisms of a single species (intraspecific competition) or two or more individuals of different species (interspecific competition) attempting to use the same scarce resources in the same ecosystem.
constancy
Ability of a living system, such as a population, to maintain a certain size. Compare inertia, resilience. See homeostasis.
disturbance
A discrete event that disrupts an ecosystem or community. Examples of natural disturbances include fires, hurricanes, tornadoes, droughts, and floods. Examples of human-caused disturbances include deforestation, overgrazing, and plowing.
ecological succession
Process in which communities of plant and animal species in a particular area are replaced over time by a series of different and often more complex communities. See primary succession, secondary succession.
ecosystem services
Natural services or natural capital that support life on the earth and are essential to the quality of human life and the functioning of the world's economies. See natural resources.
epiphyte
Plant that uses its roots to attach itself to branches high in trees, especially in tropical forests.
exotic species
See nonnative species.
foundation species
Species that plays a major role in shaping communities by creating and enhancing a habitat that benefits other species. Compare indicator species, keystone species, native species, nonnative species.
habitat fragmentation
Breakup of a habitat into smaller pieces, usually as a result of human activities.
host
Plant or animal on which a parasite feeds.
immature community
Community at an early stage of ecological succession. It usually has a low number of species and ecological niches and cannot capture and use energy and cycle critical nutrients as efficiently as more complex, mature communities. Compare mature community.
immigrant species
See nonnative species.
indicator species
Species that serve as early warnings that a community or ecosystem is being degraded. Compare keystone species, native species, nonnative species.
inertia
Ability of a living system to resist being disturbed or altered. Compare constancy, resilience.
interspecific competition
Attempts by members of two or more species to use the same limited resources in an ecosystem. See competition, competitive exclusion principle, intraspecific competition.
intraspecific competition
Attempts by two or more organisms of a single species to use the same limited resources in an ecosystem. See competition, interspecific competition.
invasive species
See nonnative species.
keystone species
Species that play roles affecting many other organisms in an ecosystem. Compare indicator species, native species, nonnative species.
law of tolerance
The existence, abundance, and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by the species. See threshold effect.
mature community
Fairly stable, self-sustaining community in an advanced stage of ecological succession; usually has a diverse array of species and ecological niches; captures and uses energy and cycles critical chemicals more efficiently than simpler, immature communities. Compare immature community.
mutualism
Type of species interaction in which both participating species generally benefit. Compare commensalism.
native species
Species that normally live and thrive in a particular ecosystem. Compare indicator species, keystone species, nonnative species.
nonnative species
Species that migrate into an ecosystem or are deliberately or accidentally introduced into an ecosystem by humans. Compare native species.
parasite
Consumer organism that lives on or in and feeds on a living plant or animal, known as the host, over an extended period of time. The parasite draws nourishment from and gradually weakens its host; it may or may not kill the host. See parasitism.
parasitism
Interaction between species in which one organism, called the parasite, preys on another organism, called the host, by living on or in the host. See host, parasite.
pathogen
Organism that produces disease.
perennial
Plant that can live for more than 2 years. Compare annual.
pioneer community
First integrated set of plants, animals, and decomposers found in an area undergoing primary ecological succession. See immature community, mature community.
pioneer species
First hardy species, often microbes, mosses, and lichens, that begin colonizing a site as the first stage of ecological succession. See ecological succession, pioneer community.
predation
Situation in which an organism of one species (the predator) captures and feeds on parts or all of an organism of another species (the prey).
predator
Organism that captures and feeds on parts or all of an organism of another species (the prey).
predator[[endash]]prey relationship
Interaction between two organisms of different species in which one organism, called the predator, captures and feeds on parts or all of another organism, called the prey.
prey
Organism that is captured and serves as a source of food for an organism of another species (the predator).
primary succession
Ecological succession in a bare area that has never been occupied by a community of organisms. See ecological succession. Compare secondary succession.
resilience
Ability of a living system to restore itself to original condition after being exposed to an outside disturbance that is not too drastic. See constancy, inertia.
resource partitioning
Process of dividing up resources in an ecosystem so that species with similar needs (overlapping ecological niches) use the same scarce resources at different times, in different ways, or in different places. See ecological niche, fundamental niche, realized niche.
secondary succession
Ecological succession in an area in which natural vegetation has been removed or destroyed but the soil is not destroyed. See ecological succession. Compare primary succession.
species equilibrium model
See theory of island biogeography.
species evenness
Abundance of individuals within each species contained in a community.
species richness
Number of different species contained in a community.
succession
See ecological succession, primary succession, secondary succession.
theory of island biogeography
The number of species found on an island is determined by a balance between two factors: the immigration rate (of species new to the island) from other inhabited areas and the extinction rate (of species established on the island). The model predicts that at some point the rates of immigration and extinction will reach an equilibrium point that determines the island's average number of different species (species diversity).
threshold effect
The harmful or fatal effect of a small change in environmental conditions that exceeds the limit of tolerance of an organism or population of a species. See law of tolerance.
tolerance limits
Minimum and maximum limits for physical conditions (such as temperature) and concentrations of chemical substances beyond which no members of a particular species can survive. See law of tolerance.
age structure
Percentage of the population (or number of people of each sex) at each age level in a population.
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. Compare sexual reproduction.
biotic potential
Maximum rate at which the population of a given species can increase when there are no limits on its rate of growth. See environmental resistance.
carrying capacity (K)
Maximum population of a particular species that a given habitat can support over a given period.
dieback
Sharp reduction in the population of a species when its numbers exceed the carrying capacity of its habitat. See carrying capacity.
environmental resistance
All the limiting factors that act together to limit the growth of a population. See biotic potential, limiting factor.
exponential growth
Growth in which some quantity, such as population size or economic output, increases at a constant rate per unit of time. An example is the growth sequence 2, 4, 8, 16, 32, 64 and so on; when the increase in quantity over time is plotted, this type of growth yields a curve shaped like the letter J. Compare linear growth.
intrinsic rate of increase (r)
Rate at which a population could grow if it had unlimited resources. Compare environmental resistance.
J-shaped curve
Curve with a shape similar to that of the letter J; can represent prolonged exponential growth. See exponential growth.
K-selected species
Species that produce a few, often fairly large offspring but invest a great deal of time and energy to ensure that most of those offspring reach reproductive age. Compare r-selected species.
K-strategists
See K-selected species.
linear growth
Growth in which a quantity increases by some fixed amount during each unit of time. An example is growth that increases in the sequence 2, 4, 6, 8, 10, and so on. Compare exponential growth.
logistic growth
Pattern in which exponential population growth occurs when the population is small, and population growth decreases steadily with time as the population approaches the carrying capacity. See S-shaped curve.
population density
Number of organisms in a particular population found in a specified area or volume.
population dispersion
General pattern in which the members of a population are arranged throughout its habitat.
population distribution
Variation of population density over a particular geographic area. For example, a country has a high population density in its urban areas and a much lower population density in rural areas.
population dynamics
Major abiotic and biotic factors that tend to increase or decrease the population size and age and sex composition of a species.
population size
Number of individuals making up a population's gene pool.
r-selected species
Species that reproduce early in their life span and produce large numbers of usually small and short-lived offspring in a short period. Compare K-selected species.
r-strategists
See r-selected species.
reproduction
Production of offspring by one or more parents.
reproductive potential
See biotic potential.
S-shaped curve
Leveling off of an exponential, J-shaped curve when a rapidly growing population exceeds the carrying capacity of its environment and ceases to grow.
sexual reproduction
Reproduction in organisms that produce offspring by combining sex cells or gametes (such as ovum and sperm) from both parents. This produces offspring that have combinations of traits from their parents. Compare asexual reproduction.
survivorship curve
Graph showing the number of survivors in different age groups for a particular species.
age structure
Percentage of the population (or number of people of each sex) at each age level in a population.
birth rate
See crude birth rate.
crude birth rate
Annual number of live births per 1,000 people in the population of a geographic area at the midpoint of a given year. Compare crude death rate.
crude death rate
Annual number of deaths per 1,000 people in the population of a geographic area at the midpoint of a given year. Compare crude birth rate.
death rate
See crude death rate.
demographic transition
Hypothesis that countries, as they become industrialized, have declines in death rates followed by declines in birth rates.
emigration
Movement of people out of a specific geographic area. See migration. Compare immigration.
family planning
Providing information, clinical services, and contraceptives to help people choose the number and spacing of children they want to have.
fertility
The number of births that occur to an individual woman or in a population.
immigration
Migration of people into a country or area to take up permanent residence.
infant mortality rate
Number of babies out of every 1,000 born each year that die before their first birthday.
life expectancy
Average number of years a newborn infant can be expected to live.
migration
Movement of people into and out of a specific geographic area. See immigration, emigration.
population change
An increase or decrease in the size of a population. It is equal to (Births + Immigration) [[minus]] (Deaths + Emigration).
replacement-level fertility
Number of children a couple must have to replace them. The average for a country or the world usually is slightly higher than 2 children per couple (2.1 in the United States and 2.5 in some developing countries) because some children die before reaching their reproductive years. See also total fertility rate.
total fertility rate (TFR)
Estimate of the average number of children who will be born alive to a woman during her lifetime if she passes through all her childbearing years (ages 15[[endash]]44) conforming to age-specific fertility rates of a given year. In simpler terms, it is an estimate of the average number of children a woman will have during her childbearing years.