A human-based study that compares a group of smokers to non-smokers to determine the effects of smoking is
a. an epidemiological study.
b. a case study.
c. not likely to be funded.
d. not going to tell about future risks.
Answer: A
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What adaptation has allowed humans to increase their chances of survival and reproduction through gripping and using tools?
A. walking upright on two legs B. physical strength C. complex brain D. opposable thumbs E. five digits on each hand
What electronegativity difference is associated with a nonpolar covalent bond?
A) exactly 0 B) less than 0.5 C) between 0.5 and 1.9 D) greater than 1.9
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A. They provide significant free oxygen. B. They serve as natural barriers. C. They protect coastlines from erosion. D. They provide habitats for one-quarter of all marine organisms. E. They provide one-tenth of the global fish catch.
During which of the following processes is oceanic crust recycled?
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