Greenhouse gases _____
a. help keep Earth's surface warm enough for life
b. are released by natural and human activities
c. are at higher levels than they were 100 years ago
d. all of these
D
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The ability to isolate and produce many copies of specific ____________________ molecules had a great impact on
many areas of genetic research. Fill in the blank(s) with the appropriate word(s).
Organisms whose sole source of carbon for growth is CO2 are called ________.
A. autotrophs B. consumers C. saprophytes D. lithotrophs E. decomposers
Which event occurred first?
a. evolution of vascular plants b. evolution of modern humans c. oxygen accumulation in the Earth's atmosphere d. evolution of prokaryotes e. evolution of reptiles
A dance that recruits other bees into foraging more
than 100 meters distant from the hive is indicated by a. A. b. B. c. C. d. D. e. E.