18)
in the carbon cycle, carbon is transferred from animals to decomposers in all of the following ways except
a) as waste.
b) in dead carcasses.
c) as carbon dioxide.
d) in scraps of discarded food.

19)
which nutrient cycle is most affected by the over-use of ammonia fertilizers on commercial farms, as well as by the accumulation of waste on cattle farms and feed lots?
a) water
b) carbon
c) nitrogen
d) phosphorus

20)
which pollutant would probably not directly harm most plants, despite having a negative impact on human populations and the environment?
a) motor oil from automobile runoff
b) acid rain from smoke stack emissions
c) carbon dioxide from automobile exhaust
d) salt pollution from fertilizers and erosion

21)
when deforestation occurs in an area, what immediate effect does this have on the water cycle?
a) more water is returned to the atmosphere.
b) there is less runoff water, but more transpiration.
c) more precipitation is formed, because there is more evaporation.
d) more runoff water is created, and less is returned to the atmosphere.