Problem 4
Describe two ways in which the sudden appearance of oxygen in the atmosphere about 2.5 billion years ago influenced the development of modern life-forms.
Problem 6
Contrast the eastern and western margins of North America during the Cenozoic era in terms of their relationships to plate boundaries.
Problem 7
Explain how prokaryotes, which were the first known living organisms on Earth, could live despite the lack of oxygen.
Problem 10
Between 300 and 250 million years ago, plate movement assembled all the previously separated landmasses together to form the supercontinent Pangaea. The formation of Pangaea resulted in deeper ocean basins and a drop in sea level, causing shallow coastal areas to dry up. Thus, in addition to rearranging the geography of our planet, continental drift had a major impact on life on Earth. Use the accompanying diagrams and the information above to answer the following: a. Which of the following types of habitats would likely diminish in size during the formation of a supercontinent: deep-ocean habitats, wetlands, shallow marine environments, or terrestrial (land) habitats? Explain. b. During the breakup of a supercontinent, what would happen to sea level- would it remain the same, rise, or fall? c. Explain how and why the development of an extensive oceanic ridge system that forms during the breakup of a supercontinent affects sea level.
Problem 11
Suggest a geologic reason why the rift valley system of East Africa is so rich in human ancestor fossils.
Problem 13
If life on Earth originated from simple chemical compounds such as methane and ammonia, or hydrogen sulphide, why don't we observe the origin of new forms of life today?
