As free oxygen increased in the early atmosphere,
a. most anaerobic organisms perished.
b. some anaerobic organisms survived in seafloor
sediments.
c. organisms evolved pathways for detoxifying
oxygen.
d. the amount of UV radiation reaching the earth
decreased.
e. all of these happened.
Answer: e
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An organism whose decline or removal from a habitat causes many other species numbers to change dramatically is called __________ species.
A. a keystone B. a synergistic C. a nominal D. an introduced
The biosphere
a. is located in the Northern Hemisphere. b. contains organisms with similar needs. c. has environmental conditions of similar temperature, pressure, and salinity. d. supports all of life on earth. e. is restricted to the continents.
To develop an effective simulation model for an ecosystem, a researcher must do all of the following
EXCEPT
a. describe food webs. b. develop relevant equations. c. estimate productivity of all populations. d. identify major species. e. manipulate species richness.
The genome of a virus can be
a. DNA or RNA b. DNA and RNA c. DNA only d. RNA only