Part 1 of 2 -
100.0/ 100.0 Points
Question 1 of 40 5.0/ 5.0 Points As demonstrated by the Keeling curve, carbon dioxide concentration in the atmosphere was expected to reach __________ ppm by 2010. But, in fact, carbon concentration exceeded that level in 2013 and is still rising.
A. 250 B. 300 C. 350 D. 400
Question 2 of 40 5.0/ 5.0 Points When ecologists are examining, for example, the ways that energy is distributed over a food chain or the rate at which nutrients are recycled, they are engaged in __________ in order to understand how the whole system works.

Question 3 of 40 5.0/ 5.0 Points The actual location of some natural space inhabited by particular flora and fauna is called a/an:
Question 4 of 40 5.0/ 5.0 Points In which of these semi-arid grasslands did people first domesticate horses?

Question 5 of 40 5.0/ 5.0 Points Which of the following statements characterizes temperate grasslands?
A. The rainy season lasts for six to eight months. B. During the parched dry season, fires, intended and natural, turn vegetation to ash. C. We find perennial grasses as well as flowering plants called forbs. D. We find stands of trees separated by grasses.
Question 6 of 40 5.0/ 5.0 Points Which of these planets is in the so-called “Goldilocks Zone”?
