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  3. Why past generations regarded women as the weaker sex is a mystery to anyone who has examined the question objectively, for they

Why past generations regarded women as the weaker sex is a mystery to anyone who has examined the question objectively, for they

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问题     Why past generations regarded women as the weaker sex is a mystery to anyone who has examined the question objectively, for they are far stronger than men—outliving them in pretty well every society in the world. Partly that is because men are more violent, and their violence is largely directed at other men. But partly it is physiological. Men seem to wear out faster than women do. Yet no one knows why.
    Madeleine Beekman of the University of Sydney and her colleagues, however, have a hypothesis. They think at least some of the blame lies with subcellular structures called mitochondria (线粒体), which provide the body with its power by burning glucose and using the energy thus released to make a molecule that is biology’s universal fuel.
    Mitochondria are amusing. They are descendants of bacteria that teamed up with the ancestors of animal and plant cells about a billion years ago. They retain their own genes, which is where problems start. To avoid fights between genetically different mitochondria in the same cell, most species have arranged for their mitochondria to come from only one parent—usually the mother so that a male’s mitochondria are stuck in an evolutionary dead end. They can neither evolve in male-specific ways nor be passed on to the next generation.
    Male and female physiologies are sufficiently similar for this not to be a central problem, but Dr. Beekman thinks it may matter at the margins. She observes that one disease, caused by a faulty mitochondrial gene, occurs in only 10% of women whose cellular power-packs include the damaged gene, but in 50% of men whose mitochondria are so hindered. The gene in question, in other words, is less likely to harm a woman than a man. She then lists a lot of other diseases, including ones far commoner that sometimes have a mitochondrial component, and speculates that some of these may prove to be either more common or more serious in men than in women. As far as her literature search can show, this is not something that has yet been looked into.
    Part of the reason for this absence of information may be that few doctors think like evolutionary biologists, so they fail to ask appropriate questions. Dr Beekman’s hypothesis may turn out to be wrong, but sounds remarkably plausible and certainly worth investigating.
Which of the following statements is true about mitochondria?
选项 A、They are mostly located outside cells.
B、They are passed down by the mother.
C、They don’t have any gene of their own.
D、They are likely to cause human diseases.
答案B
解析 文章第三段有they(mitochondria)retain their own genes(保留自己的基因)，后面又in the same cell，说明线粒体在细胞内。该段的…come from only one parent-usually the mother so that a male’s mitochondria are stuck in an evolutionary dead end说明线粒体通常由母亲遗传，而父亲的线粒体被困在死胡同中。
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