It is speculated that one of the first kinds of organic molecules formed on primitive Earth was
A. amino acid.
B. ammonia.
C. oxygen.
D. protein.
A. amino acid.
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The streptomycetes form spores on their substrate mycelia.
Answer the following statement true (T) or false (F)
In the Beadle and Tatum study, it was important that Neurospora was haploid because:a
it is easier to grow haploid molds in the laboratory. b. haploid molds have simpler nutritional requirements than do diploid molds. c. a mutation that arises is not masked by a normal allele on a homologous chromosome. d. haploid Neurospora will always mutate. e. diploid Neurospora will always mutate.
Tropical climates are warmer than temperate climates because
A. temperate climates are closer to the poles and the polar surfaces cause a reduction in heat gain. B. tropical climates have more vegetation and thus can absorb more heat. C. tropical climates receive the sun's rays at an almost perpendicular angle; since Earth is a sphere, the temperate climates receive the sun's rays at a much steeper incidence thus spreading the radiation over a broader area. D. tropical climates receive the sun's rays at a much steeper incidence thus spreading the radiation over a broader area and causing the tropics to be warmer while the temperate climates receive the sun's rays at an almost perpendicular angle, which causes some areas to be warm and other areas to be cold. E. temperate climates have more mountains and thus more snow causing the landmasses to warm slower.
The oldest fossil organisms presently known have been dated at approximately how many years old?
A) more than 4.5 billion B) less than 1.7 billion C) 4.5 billion D) 1.7 billion E) 3.4 billion