The diagram shows the amount of phosphorus measured in teragrams (1 teragram = 1×10^12) grams), in the various reservoirs of the phosphorus cycle. Which of the following is the best explanation for why there is such a small amount of phosphorus that moves into aquatic systems?
According to the diagram, the movement of phosphorus between biological organisms and soil is in a steady state in an undisturbed system. Which of the following best explains the reason for this steady movement?
Based on the diagram, which of the following reservoirs contains the most phosphorus?
The diagrams above show an area that was once a pasture that has since undergone changes to the vegetation over time. Which of the following changes in the hydrologic cycle is most likely to occur as a result of the change in vegetation in the area?
Which letter correctly identifies the part of the hydrologic cycle that is most directly affected by impervious building materials, such as concrete and asphalt?
Which letter correctly identifies a process of the hydrologic cycle in which the phase of water is changed from a liquid to a gas?
Which of the following best describes gross primary productivity in an ecosystem?
Which of the following best describes the net primary productivity of an ecosystem?
Scientists calculated the net primary productivity at two different forest sites. Both forests have the same gross primary productivity. Forest A has a net primary productivity of 1,650kcal/m^2/year, and forest B has a net primary productivity of 1,110kcal/m^2/year. Which of the following statements is best supported by the data?
Which of the following best describes the movement of energy in an ecosystem?
The table above shows the balanced chemical equations that represent three processes that are part of the nitrogen cycle. Which of the following is exemplified by the equations above?
Which of the following best explains why terrestrial trophic pyramids usually do not have levels higher than tertiary consumers?
In a given ecosystem, producers convert solar energy into 15,000kcal of chemical energy stored in organic compounds. Which of the following is the most likely amount of energy available to secondary consumers?
Algae in an aquatic food chain convert solar energy into 93,000 kilocalories of plant tissue. Which of the following values best represents the amount of energy available for primary consumers in the food chain?
Algae in an aquatic food chain convert solar energy into 93,000 kilocalories of plant tissue. Which of the following values best represents the amount of energy available for secondary consumers in the food chain?
The X in a cell indicates that the organism is eaten by the consumer in the first column.
Based on the data in the table, which of the following pairs of organisms has two ecological relationships, both competition and predation?
Which of the following categories of organisms, which are required for the cycling of matter in an ecosystem, is missing from the table?