What do researchers use to directly measure the rate of productivity?
a. Carbon-12
b. Biomass
c. Carbon-14
d. Chloroplasts
ANS: C
Scientists "tag" carbon by radioactivity. The c-14 behaves the same way normal c-12 does, but it can
easily be tracked through photosynthesis. Information can be found in the section Measuring Primary
Productivity.
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Things like open space or clean air can be considered a resource because they are
A. Exhaustible B. Valued by people C. Essential for efficient production D. Hard to find E. Expensive
The ability to feed the growing world population was addressed by the
A) Industrial Revolution. B) Medical Revolution. C) Green Revolution. D) Environmental Revolution.
The gravity model predicts that the optimal location of a service is
A) directly related to the number of people and services in the area and inversely related to the lengths of highways and railways that access it. B) directly related to the range in the area and inversely related to the hinterland. C) directly related to the number of people in the area and inversely related to the distance people must travel to access it. D) directly related to the median of people in the area and inversely related to the meridian of people who travel to access it. E) directly related to the distance people must travel and inversely related to the number of people in the area.
The two most abundant gases in the atmosphere are
A) nitrogen and oxygen. B) water vapor and carbon dioxide. C) nitrogen and water vapor. D) oxygen and carbon dioxide.