2.Black Americans are, on the whole, about twice as likely as White Americans to develop high blood pressure. This likelihood also holds for westernized Black Africans when compared to White Africans. Researchers have hypothesized that this predisposition in westernized Blacks may reflect an interaction between western high-salt diets and genes that adapted to an environmental scarcity of salt. Which of the following statements about present-day, westernized Black Africans, if true, would most tend to confirm the researchers’ hypothesis? (A) The blood pressures of those descended from peoples situated throughout their history in Senegal and Gambia, where salt was always available, are low. (B) The unusually high salt consumption in certain areas of Africa represents a serious health problem. (C) Because of their blood pressure levels, most White Africans have markedly decreased their salt consumption. (D) Blood pressures are low among the Yoruba, who, throughout their history, have been situated far inland from sources of sea salt and far south of Saharan salt mines. (E) No significant differences in salt metabolism have been found between those people who have had salt available throughout their history and those who have not. 答案是A,我选了D。题干我能看懂,意思就是黑人基因是适应少盐的环境的,但是到了西方接触了多盐的食物就得了高血压。A说那些来自多盐地方的人的后代血压低。这个为什么能加强结论? 该选项说明了基因确实在调整人对环境的适应性。因为Senegal和Gambia都是非洲国家,他们的初始基因和Black American一样,证明了Black American的基因不是一开始就没法适应多盐的食物。 |
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