About how often do earth's magnetic poles reverse?
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a. every 22 years
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b. every 100 million years
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c. every billion years
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d. every 250,000 years

Read the following scenario to answer the following question. in some zoos, rare crosses between a male lion and a female tiger have produced hybrid offspring called "ligers." male ligers are sterile but some female ligers are fertile. in the wild, lion and tiger ranges do not naturally overlap, making such a cross unlikely. furthermore, the solitary behavior of tigers and the social organizations of lions create behavioral differences. applying the biological species concept, the sterility of ligers reveals that a. lions are probably a subspecies of tigers b. tigers and lions are the same species c. a new species called "ligers" is forming d. tigers and lions are separate species

What makes a dominant allele different from a recessive allele

Is there any solid scientific evidence that humans have been cloned?