Weegy: Until the early Proterozoic there were only negligible amounts of free oxygen in the atmosphere.
User: The Cenozoic Era is best described as the era in which
A. a mass extinction event occurred.
B. dinosaurs emerged.
C. mammals began to dominate the land.
D. multicellular life diversified.
Weegy: The Cenozoic Era is best described as the era in which mammals began to dominate the land.
User: A major consequence of ozone depletion is that
A. more harmful UV rays will reach the earth's surface.
B. solar energy will become ineffective.
C. acid rain will increase.
D. certain parts of the earth will become over-vegetated.
Weegy: A major consequence of ozone depletion is that more harmful UV rays will reach the earth's surface.
User: Which of the following is a nonrenewable resource?
A. Tree
B. Carbon
C. Gold
D. River
Weegy: Gold is a nonrenewable resource.
User: If population size temporarily exceeds the environmental _______, deaths will increase until the population size returns to previous levels.
A. density
B. carrying capacity
C. growth factor
D. reclamation
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