首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Women live longer than men because they are spoiled for choice. That is the startling conclusion of an international group of sc
Women live longer than men because they are spoiled for choice. That is the startling conclusion of an international group of sc
admin
2010-05-26
102
问题
Women live longer than men because they are spoiled for choice. That is the startling conclusion of an international group of scientists who say they have found the cause of female longevity.
They say females have two separate cell lines in their bodies, while men have only one. Women in old age can "choose" the more robust (强壮的) of these lines and survive for many more years.
Why there should be such a persistent cross-cultural gap between the life spans of the sexes has baffled scientists until now. In a paper in the journal Blood, and reported in the current issue of New Scientist, researchers at Odense University in Denmark and Ulleval University Hospital in Norway point to a key difference in the sex-determining chromosomes (染色体) found in the cells of men and women.
Every cell in a woman’s body has two X chromosomes, one inherited from her mother and the other from her father. In each cell, one of these two X chromosomes is switched off. This means that a woman is a mosaic (混合体) of two cell lines: one derived from her father’s X chromosome, the other from her mother’s. By contrast, every cell in a man’s body has an X and a Y chromosome, neither of which is turned off. He has only one cell line. This difference could be crucial in determining the long-term health of men and women, scientists concluded, and so they decided to examine cells taken from young women.
They found an even division between their two different lines. However, when they looked at elderly females they found their bodies now favoured one set of cells at the expense of the other line. "This suggests that one of the cell lines is ’better’ than the other," say the researchers. In other words, women’s bodies may select the more vigorous of the two cell lines and allow it to predominate the twilight of their years, giving them a crucial advantage over men, who have no chance of choosing the healthier of two sets of cells.
The difference in the sex-determining chromosomes is that______.
选项
A、a woman inherits X chromosomes from her mother while a man from his father
B、a woman inherits Y chromosomes from her mother while a man from his father
C、a woman has an X and a Y chromosome while a man has two of them
D、a woman has two X chromosomes while a man has an X and a Y chromosome
答案
D
解析
转载请注明原文地址:https://kaotiyun.com/show/fcV7777K
0
大学英语四级
相关试题推荐
____________(众所周知),abalanceddietandexercisekeeponefitandhealthy.
A、Hewaspresidentwhenthecitywaspurchased.B、HeledtheAmericanforcesinanearbybattle.C、HedesignedJacksonSquarein
Toooftenyoungpeoplegetthemselvesemploymentquitebyaccident,notknowingwhatliesinthewayofopportunityforpromotio
Thepartoftheenvironmentalmovementthatdrawsmyfirm’sattentionisthedesignofcities,buildingsandproducts.Whenwed
Thepartoftheenvironmentalmovementthatdrawsmyfirm’sattentionisthedesignofcities,buildingsandproducts.Whenwed
Forthispart,youareallowed30minutestowriteacompositiononthetopicElectronicGames:ABlessingoraCurse?Youshoul
Theappealofadvertisingtobuyingmotivescanhavebothnegativeandpositiveeffects.Consumersmaybe【B1】______tobuyapr
StudyinginSydney,Australia—anOverviewforInternationalStudentsAustraliahasbeenapopularchoiceforthousandsofi
WhenIwasachildIhadviolinlessonsforsixorsevenyears.Musicgavemealotofpleasures【M1】______andI
WhenIwasachildIhadviolinlessonsforsixorsevenyears.Musicgavemealotofpleasures【M1】______andI
随机试题
A公司于2009年6月在上海证券交易所上市。2013年4月,A公司聘请B证券公司作为向不特定对象公开募集股份(以下简称“增发”)的保荐人。B证券公司就本次增发编制的发行文件有关要点如下:(1)A公司近3年的有关财务数据如下:A公司于2010年度以资本
中麻黄鳞叶特征是
女性患者,40岁,间断头痛1年,以晨起时重,近1个月病情加重伴呕吐。查体:双眼底视乳头水肿,左眼外展不全,右侧肢体肌力Ⅳ级,右侧Babinski征阳性。该患者最可能的诊断是
核象右移是指占白细胞分类总数3%以上为中性粒细胞,其核分叶为
局部浸润麻醉最常用的药物是
不属于丁级测绘资质业务范围的是()。
施工过程质量控制中,不包括()。
A注册会计师负责审计X公司2014年财务报表。了解X公司采购业务流程中后发现以下与付款业务相关的内部控制,其中可能表明采购业务内部控制存在缺陷的是()。
抗生素的发明和使用,使病菌一度不再是人类的致命威胁。但是,在人类使用抗生素治疗疾病的同时,病菌的耐药性也在增加,由于滥用抗生素,出现了目前难以控制的“超级病菌”。上述事实表明()。
Whenmymother’shealthwasfailing,Iwasthe"bad"sisterwholivedfarawayandwasn’tinvolved.Mysisterhelpedmyparents.
最新回复
(
0
)