22.  A linear depiction of energy flow in an ecosystem is a?

26.  Transpiration is most closely associated with:

50.  Stratospheric ozone is important because it:

37.  The most productive region of a lake is the ____ zone.

29.  The primary reason that Earth experiences seasons is because of the:

13.  Habitat is best described as:  

44.  Today, the major danger to species is:

41.  Building roads, parking lots, building and bridges all contribute to:

21.  Approximately what proportion of the radiant energy entering an ecosystem is used in photosynthesis?

11.  A biological community and its abiotic environment together comprise which of the following?