What is the primary sink for nitrogen for living organisms?

Which bacteria are responsible for converting nitrogen gas into ammonia?

What is the process by which ammonia is converted into nitrite and then nitrate in the soil?

Which process returns nitrogen gas to the atmosphere?

Which component of the nitrogen cycle involves lightning?

What happens to excess nitrogen in aquatic ecosystems?

Which organisms play a major role in the nitrogen cycle by breaking down organic matter?

What is the process by which carbon dioxide is released into the atmosphere from burning fossil fuels?

Which of the following is NOT a greenhouse gas?

What is the process by which carbon is removed from the atmosphere?

What is the primary way in which humans contribute to the increase of carbon dioxide in the atmosphere?

Which of the following is the largest carbon sink?

What is the name of the process by which carbon is released from dead organisms into the environment?

Which of the following human activities contributes to deforestation?

What is the primary driving force of the hydrologic cycle?

What is the process of water evaporating from plant leaves called?

What is the process of water changing from a gas to a liquid called?

What is the process of water seeping into the soil called?

What is the process of water falling from clouds called?

What is the process of water flowing over the land surface called?

What is the name for the area where all the water that is underground is stored and moves slowly through layers of rock and soil?

What is the process of ice turning directly into water vapor called?

Which of the following biomes is characterized by long, cold winters and short, cool summers?

Which biome is characterized by low precipitation, high temperatures, and sparse vegetation?

Which biome is characterized by moderate temperatures and abundant rainfall, and is home to the largest variety of species?

Which biome is characterized by permafrost and low-growing vegetation such as mosses and lichens?

Which biome is characterized by tall grasses and occasional trees, and is home to large grazing animals such as bison?

Which biome is characterized by coniferous forests and long, cold winters?

Which biome is characterized by a mix of coniferous and deciduous trees, and experiences all four seasons?

Which biome is characterized by grasses and low shrubs, and is found in areas with low precipitation such as the African plains?

What is an aquifer?

What is ecology?

What is a biotic factor?

What is an abiotic factor?

What is a food chain?

What is a dichotomous key used for?

What does 'dichotomous' mean?

Which state has the highest population density in the U.S.?

Which type of growth results in a sigmoidal (S-shaped) curve?

Which growth model is more realistic for a population that is near its carrying capacity?

What shape does the graph of exponential growth have?

What is a limiting factor?

Which of the following is an example of a biotic limiting factor?

What is the carrying capacity of an ecosystem?

Which of the following is an example of a density-dependent limiting factor?

Which of the following is an example of a density-independent limiting factor?