The zone of life on Earth; sum total of all ecosystems on Earth.

A term that describes a nonliving factor in an ecosystem.

A species that is found in its originating location and is generally restricted to that geographic area.

An organism that obtains nutrients by consuming dead and decaying organic matter which allows nutrients to be accessible to other organisms.

Chemical or physical factor that limits the existence, growth, abundance, or distribution of an individual organism or a population.

The artificial cultivation of food, fiber, and other goods by the systematic growing and harvesting of various organisms.

An area that provides an organism with its basic needs for survival.

A complex arrangement of interrelated food chains illustrating the flow of energy between interdependent organisms.

An organism that obtains energy by feeding on other organisms or their remains.

The position of an organism in relation to the flow of energy and inorganic nutrients through an ecosystem (e.g., producer, consumer, and decomposer).

Different populations of organisms interacting in a shared environment.

The lowest taxonomic level of biological classification consisting of organisms capable of reproduction that results in fertile offspring.

A set of interacting or interdependent components, real or abstract, that form an integrated

whole. An open system is able to interact with its environment. A closed system is isolated from its environment.

A system composed of organisms and nonliving components of an environment.

A relationship between two organisms (i.e., mutualism, in which both organisms benefit; parasitism, in which one organism benefits and the other organism is harmed; and commensalism, in which one organism benefits and the other organism does not benefit or is harmed).

An organism that uses a primary energy source to conduct photosynthesis or chemosynthesis.

A species normally living outside a distribution range that has been introduced through either deliberate or accidental human activity; also can be known as introduced, invasive, alien, non-indigenous, or exotic.

A group of individuals of the same species living in a specific geographical area and reproducing.

The total surroundings of an organism or a group of organisms.

A group of students measured a ten-square-meter section of a pond ecosystem and recorded observations. Which statement is a testable hypothesis?

Which description is the best example of a population?

A researcher observing an ecosystem describes the amount of sunlight, precipitation, and type of soil present. Which factors is the researcher most likely describing?

Scientists observed that the populations of top-level consumers in a particular ecosystem were rapidly decreasing. Further studies revealed that there was also a decline in producer productivity. Which other changes did the scientists most likely observe in the ecosystem?

A student studying the biosphere makes a list of biotic and abiotic characteristics of various biomes. Which characteristic is considered a biotic factor?

Which example describes a mutualistic relationship between organisms?

Most of the water on Earth is located in the oceans and has a salinity of about 3.5%. Which statement best explains why rain is fresh water and has a very low salinity?

Why are nonnative species often considered a disturbance in an ecosystem?

A student wrote several observations in a field notebook. Which term best classifies all of the student’s observations?

A species of snapping turtles has a tongue that resembles a worm. The tongue is used to attract small fish. Which best describes the interaction between the fish and the snapping turtle?

Which sequence correctly describes the flow of energy between organisms in the marine food web?

Which statement correctly describes how nitrogen in the soil returns to the atmosphere?

Agricultural runoff can carry fertilizers into lakes and streams. This runoff can cause algae populations to greatly increase. Which effect does this change in the algae population sizes most likely have on affected lakes and streams?

Which energy transfer most likely occurs between organisms in the food web to the right?

A farmer observed that an increase in a field’s soil nitrogen content was followed by an increase in producer productivity. What does this observation most likely indicate about the relationship between nitrogen and the producers in the field?

In Pennsylvania, a nonnative plant called stiltgrass out-competes native plants in many forest ecosystems. Which statement best describes how the spread of stiltgrass negatively affects native herbivores?