<span>Women's mean hemoglobin levels are about 12% less than the mean hemoglobin levels of men. This sex-related difference is observed in many species of animals, such as birds and reptiles. It's believed this difference exists in humans between males and females because men have larger bones, which means they would have more blood cells producing bone marrow. Additionally, men's kidneys have a larger diameter than women's kidneys, which would lead to increased red blood cell production.</span>
In humans gene flow usually comes about through the actual migration of human populations, either voluntary or forced. Although gene flow does not change allele frequencies for a species as a whole, it can alter allele frequencies in local populations.
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Explanation:
The flow of the river is dependent upon the position along the stream in terms of the gradient. Near the top of a high gradient, the flow will be less than that near the bottom. Likewise, the steeper the river's gradient, the faster the flow of water (due to the pull of water down the gradient by gravity).
A vaccine can help keep people healthy and protect them from a certain virus. For example people in the United States get the flu shot when they get this shot the vaccine wont magically get rid of the virus but rather help them fight it off and protect them in the future if they keep up to date getting the vaccine
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