6. The region of the Earth where life exists is known as:
7. Epidemic diseases include all of the following except:
8. Decreased death rate and the accelerated rate of human population growth are related to: I. improved sanitation and health II. increased food supply III. control of disease-spreading organisms
9. Which of the following cycles involves the movement of water from the surface of the Earth through the atmosphere back to the surface of the Earth?
10. The substance with the greatest significance for the global carbonate-silicate cycle is:
11. According to the Environmental Science text, an ecosystem: