One way that bacteria and fungi are important to the environment is that they

• are a major food source in many ecosystems.

• produce oxygen.

• use the sun’s energy to make their own food.

• break down dead organisms.

Estuaries are very productive ecosystems because they receive fresh nutrients from

• lakes and ponds.

• streams and springs.

• rivers and oceans.

• marshes and swamps.

Which of the following is not an environmental function of wetlands?

• trapping carbon that would otherwise be released into the air

• absorbing and removing pollutants from water

• controlling floods

• increasing runoff

The process of two species changing genetically in response to long-term interactions with each other is

• artificial selection.

• selective breeding.

• coevolution.

• resistance.

The group that does not receive the experimental treatment in an experiment is the

• control group.

• variable.

• data.

• experimental group.

The term biomass refers to the total

• mass of all living things on Earth.

• dry mass of the organisms in a given area.

• unused material excreted as waste.

• producer-to-consumer ratio.

Plants play a crucial role in the carbon cycle because they

• do not release carbon dioxide during cellular respiration.

• are chemically converted into fossil fuels when burned.

• allow carbon to enter an ecosystem through photosynthesis.

• have special bacteria that live in their root systems.

Which two biogeochemical cycles depend directly on photosynthesis?

• the hydrologic cycle and the oxygen cycle

• the oxygen cycle and the carbon cycle

• the carbon cycle and the phosphorus cycle

• the nitrogen cycle and the phosphorus cycle

Which of the following describes soil and temperature in an ecosystem?

• biotic factors

• selection factors

• abiotic factors

• unnecessary factors

Food webs are models that show

• networks of feeding relationships.

• only primary consumers in an ecosystem.

• stored energy in food chains.

• one sequence of producers and consumers.