A nonliving factor - light, water, heat, rock, energy, mineral, etc.

Precipitation with a pH less than 5.6 that forms when pollutants mix with water vapor.

Any of a set of possible forms of a gene.

The variety and complexity of species present and interacting in an ecosystem.

The changing of organic matter into useful liquid, gas, or fuel.

The application of scientific/health care theories to develop products (i.e. artificial heart).

A community of living organisms of a single major ecological region.

A living part/factor of the environment.

A group of related objects that have feedback and can modify themselves.

Economic goods or products before they are processed and given a brand name.

The process of mixing decaying leaves, manure, and other matter to fertilize soil.

Those organisms that obtain energy by feeding on other organisms and their remains.

An organism that obtains nutrients by consuming dead organic matter.

To trace the outline; to draw, to sketch; to depict or picture.

To remove salts and other chemicals from sea or saline water.

Divided (or dividing) into two parts or classifications.

A community of living organisms and their interrelated environment.

The branch of biology dealing with the development of living things from a fertilized egg.

A species that is in danger of extinction.

The application of scientific and mathematics principles to design products/structures.

The total surroundings influencing each living being's existence (air, water, soil, etc.).

A protein that increases the rate of a chemical reaction without being changed by the reaction; an organic catalyst.

The design of equipment or devices to fit the human body.

A process of change that explains why what we see today is different from what existed in the past.

The complete elimination of a species from the Earth.

Information that has been objectively verified.

A naturally or man-made condition that presents a risk or is a potential danger to life and property (landslides, earthquakes, erosion, etc.).

Water that infiltrates the soil and is located in underground reservoirs.

A solid that may cause or pose a substantial hazard to human health or the environment when improperly, stored, transported, or disposed of.

The tendency for a system to remain in a state of equilibrium by resisting change.

The scientific study of the properties, distribution, and effects of water on the Earth's surface, in the soil and rocks, and in the atmosphere.

An assertion subject to verification or proof as a premise from which a conclusion is drawn; an educated guess.

Burning or reducing to ashes.

A systematic process for using knowledge and skills to acquire and apply new knowledge.

Summarizing statement of observed experimental facts that has been tested many times and is generally accepted as true.

Relating to or living in still water.

Relating to or living in actively moving water.

The policy of constructing or creating man-made habitats, such as wetlands, to replace those lost to development.

The sequential differentiation and segregation of replicated chromosomes in a cell's nucleus that precedes complete cell division.

A description, analogy, or a representation of something that helps to understand it better.

The role played by an organism in an ecosystem.

Contamination that originates from many locations that all discharge into a single area.

Substances that cannot be replaced in this geological age.

A star that suddenly increases in brightness and returns to its original appearance in a few weeks, months, or years.

A group of related objects that do not have feedback and cannot modify themselves.

An organism that is in competition with humans for the same resource.

A variety of pest control methods that includes traps, bait, and poison.

Pollutants discharged from a single identifiable location.

An atom that gives off nuclear radiation; has the same number of protons as other atoms of the same element, but a different number of neutrons.

Collecting and reprocessing a product to make new products.

A naturally occurring raw material or energy that will be replenished through natural ecological cycles or sound management practices.

A strategy to reduce or control the chance of harm to one's health or life.

Relates concepts and ideas to one another by some measurement; a measure of size and/or incremental change.

Search for understanding the natural world using inquiry and experimentation.

The series of changes that occur in an ecosystem with the passing of time.

The ability to keep in existence or maintain.

A system of assumptions, accepted principles, and rules of procedure devised to analyze, predict, or explain the nature or behavior of a specified set of phenomena.

A theory that the various types of animals and plants have their origin in other preexisting types.

Any device used to extend human capability .

The portrayal of the position, relation, size, shape, and elevation of an area.

The physical ways humans move materials, goods, and people.

The role of an organism in nutrient and energy flow within an ecosystem.

The flow of waste materials from generation, collection, and separation to disposal.

The land area from which surface runoff drains into a stream, lake, reservoir, or other body of water.

Lands where water saturation of the soil is the dominant factor (marshes).