Which of the following molecules are believed to have been absent from the primitive reducing atmosphere?
A. nitrogen (N2)
B. oxygen (O2)
C. carbon dioxide (CO2)
D. water vapor (H2O)
E. hydrogen (H2)
Answer: B
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Why would the Sabin oral polio vaccine need to be eliminated as we get closer and closer to eradication of the polio virus?
A. Since it is a live, attenuated viral vaccine, there's always the chance it could revert back into a pathogenic state by mutation. This would introduce new strains still capable of causing the illness into human populations, thwarting elimination. B. The Sabin vaccine is cheaper than the Salk (killed virus) vaccine, but it isn't as effective at producing a protective response. We'll need to shift to the more effective Salk vaccine worldwide eventually to complete the eradication process. C. The Salk vaccine is far cheaper than the Sabin vaccine. To effectively eradicate polio, we'll need to shift all of our resources into the cheapest and easiest to deliver vaccine possible. That is the Salk vaccine. D. The Sabin vaccine can only be administered to human beings. We need to vaccinate bird populations as well to effectively control the spread of polio. Birds are a natural reservoir for the virus.
Testosterone is secreted by the _____
a. testes c. prostate gland b. hypothalamus d. pituitary gland
Which of the following is not an invasive species?
A) cheatgrass B) purple loosestrife C) ring-necked duck D) Asian longhorned beetle
If a bacterium with the ability to survive the effects of an antibiotic "pops up" in a population, it most likely
A. resulted from spontaneous mutation. B. increased in number before the antibiotic began to be used. C. was introduced from another species. D. was created by the antibiotic.