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
During the Second World War, doctors tried to save severely burned pilots with grafts of donated skin. The grafted skin looked g
During the Second World War, doctors tried to save severely burned pilots with grafts of donated skin. The grafted skin looked g
admin
2017-11-08
36
问题
During the Second World War, doctors tried to save severely burned pilots with grafts of donated skin. The grafted skin looked good for a few days, but then withered and died. Studies led by Peter Medawar—who won a 1960 Nobel Prize for his work—found that grafts of an individuals own skin did work, while those of a donor did not. We now know that the donor skin grafts failed because the recipient’s immune system recognized the grafted skin as foreign and killed it. The same process leads to the rejection of donated organs. But how does our immune system learn what is self and what is foreign?
As immunologist Daniel Davis explains in The Compatibility Gene, it is all down to specific genes—formally known as the major histocompatibility complex genes. Although our appearance, lifestyle and career path may make us feel unique, we are actually always one of a group: it is only our compatibility genes that define us as true individuals. Davis provides a well-written and easy-to-read account of the sometimes complicated biology behind the crucial genes that affect our lives so profoundly.
From early on in the evolution of life, individual cells—and later multicellular organisms— developed the ability to recognize that which was the same as them, and that which was different. Davis recounts how, when we are growing as fetuses, our compatibility genes train the immune system to recognize our own cells and tissues as "self" and so, in healthy people, they know what not to attack. Our cells are identified by the presence of unique surface molecules, coded for by the compatibility genes.
Meanwhile, our immune systems make antibodies. These are randomly generated in a kind of lottery, which means they will be able to attack a great diversity of molecules, especially those of pathogens. By chance, though, a few of these antibodies will also match the compatibility-gene molecules on our own cells. Leaving such antibodies around would be suicide—literally. To stop this, Darwinian-style selection comes into play within the immune system, eliminating any cells that produce antibodies matching "self".
Which of the following is the explanation of "our immune systems make antibodies"?
选项
A、Immune systems can recognize the grafted skin as foreign.
B、Immune systems have the ability to attack a great diversity of pathogens.
C、Immune systems are able to recognize that which was the same as them, and that which was different.
D、Immune systems make compatibility genes define us as true individuals.
答案
B
解析
根据题干将该题定位至文章最后一段。根据最后一段第二句These are randomly generated in a kind of lottery,which means they will be able to attack a great diversity of molecules,especially those of pathogens,可以选出正确选项B。其他三个选项都与题干无关。
转载请注明原文地址:https://jikaoti.com/ti/wqUFFFFM
0
大学英语四级
相关试题推荐
A、Heusedtobeherdoctor.B、Therearebetterdoctorsthanhimintown.C、It’sdifficulttomeethim.D、Heisagooddoctor.D男
A、Itisapopularsport.B、Ithasalonghistory.C、Itisrarelytriedasecondtime.D、Itisanadventurousactivity.D短文开篇即提到现
A、Alicedidn’tseemtobenervousduringherspeech.B、Aliceneedsmoretraininginmakingpublicspeeches.C、Themancanhardly
Inmanycountriesseatbeltsarenowcompulsoryforthedriverandthefrontseatpassengeratleast.Doctorsbelievethats
A、Readthepapers.B、Sortoutletters.C、Goforajog.D、Haveameeting.C男士说早餐前他会先去慢跑,C可直接从对话中听到,故为答案。
HowsciencegoeswrongScientificresearchhaschangedtheworld.Nowitneedstochangeitself.A)Asimpleideaunderli
HowsciencegoeswrongScientificresearchhaschangedtheworld.Nowitneedstochangeitself.A)Asimpleideaunderli
HowsciencegoeswrongScientificresearchhaschangedtheworld.Nowitneedstochangeitself.A)Asimpleideaunderli
ConradHiltonreallywantedtobeabanker.Instead,hesuccessfullychangedthe【C1】_____purchaseofaTexaslow-endhotelinto
随机试题
某男,27岁。淋雨后出现寒战、高热、咳嗽、咯吐铁锈色痰。应首先考虑的是
A.变质性炎症B.浆液性炎症C.增生性炎症D.化脓性炎症E.出血性炎症流行性脑脊髓膜炎属于
保险合同的法定条款有哪些?
当衬里采用树脂胶泥衬砌块材时,应先在设备或管道表面涂刷()封底料一遍。
在计算机领域通常用MIPS来描述()
—Thegamelastnightwassogood.—Yeah!Ourschoolteamwon______twopoints!
小张去机票代理处为单位团购机票10张。商务舱定价每张1200元,经济舱定价每张700元,由于买的数量较多,代理商就给予了优惠,商务舱按定价的9折付钱,经济舱按定价的6折付钱,如果他付的钱比按定价少31%,那么小张共买经济舱票的张数是()。
王某担任某县高二英语教师期间通过了硕士研究生入学考试,学校以王某服务期未满、学校英语教师不足为由不予批准王某在职学习。王某欲以剥夺其参加进修权利为由提出申诉,受理申诉的机构应当是()。
唐朝受理行政案件的司法机关是()。
设随机变量X在1,2,3,4四个数字中等可能取值,随机变量Y在1~X中等可能地取一整数值.P{X=Y}.
最新回复
(
0
)