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
医学
A、To show that enzymes are very effective. B、To point out that enzymes can sometimes fail to work. C、To explain what enzymes are
A、To show that enzymes are very effective. B、To point out that enzymes can sometimes fail to work. C、To explain what enzymes are
admin
2013-12-06
49
问题
Let’s begin today by discussing enzymes. Enzymes are what make many of the body’s biochemical reactions possible. Actually biochemical reactions can take place without them, but at much lower rates. In fact an enzyme may cause a reaction to proceed billions of times faster than it would otherwise. Before I go on to the biochemical specifics of how this works, let me provide a figurative example. I think it will help illustrate the power of enzymes more clearly. Now, suppose you got a bag and you put a bunch of locks in it, just small padlocks. Then you put in all the keys that go with the locks. And you closed the bag and shook it hard. No matter how long you shook, chances are very small that any key would get inserted in any of the locks. But if you took them all out of the bag and this time used your hands to insert the keys in the locks, you could combine them much quicker.
Enzymes act like your hands, quickly allowing chemical reactions that would otherwise take much longer. Now, there are two reasons that enzymes are so effective at enabling biochemical reactions. First, enzymes greatly reduce the amount of energy required to start the reactions, and with less energy needed the reactions can proceed a lot faster than they could without the enzyme. The second reason is that a small amount of an enzyme is needed to enable the biochemical reaction. That’s because the chemical structure of the enzyme itself does not become altered as if enables the reaction. So a single enzyme can be used to start the same biochemical reaction over and over again.
Questions 21 - 25 are based on the passage you have just heard.
21. What is the passage mainly about?
22. What point does the professor make about an enzyme when it is involved in a biochemical reaction?
23. What do enzymes do to help start a biochemical reaction?
24. Why does the professor talk about locks and keys?
25. What is enzymes?
选项
A、To show that enzymes are very effective.
B、To point out that enzymes can sometimes fail to work.
C、To explain what enzymes are made of.
D、To describe different types of enzymes.
答案
A
解析
从“In fact an enzyme may cause a reaction to proceed billions of times faster than itwould otherwise.”可知教授举挂锁和钥匙的例子是为了说明酶的高效。
转载请注明原文地址:https://kaotiyun.com/show/twU3777K
本试题收录于:
医学博士外语题库考研分类
0
医学博士外语
考研
相关试题推荐
Ihadneverbeeninthepublicwardofahospitalbefore,anditwasmyfirstexperienceofdoctorswhohandleyouwithoutspeak
I’mintheunusualpositionofbeingbothacomputerscientistandaprofessionalmusician.Onthecomputerside,I’mbestkno
Youfeelgenerallydepressedandunabletoconcentrate.Your【C1】______ofdailyactivitymaychange;youfindyourself【C2】______a
A、Inthemainlab.B、Atacomputerterminal.C、Inasmalllab.D、Beforethebulletinboard.D录音开头讲到这里是thecomputerlaborientati
A、Sheconvincedthemantotakemedicineashismajor.B、Sheaskedthemantogiveatalkonmedicine.C、Shepersuadedthemann
A、Theycontractedthediseasebybeingwiththeinfectedpeople.B、Theycontractedthediseasebybreathingthecontaminateddus
Thereisanewtypeofsmalladvertisementbecomingincreasinglycommoninnewspapersclassifiedcolumns.Itissometimesplaced
A、Jack’scarwasaccidentallylost.B、Jackwasrunoverinacaraccident.C、Jacksurvivedacaraccident.D、Jackfelloutofa
A、Bloodpoisoning.B、Apenicillin.C、Aheartattack.D、Ancaraccident.Abloodpoisoning意为“败血病”。
Becauseheworeastrangecollectionofclothesandoftentalkedtohimself,hisneighborconsideredhimeccentric.
随机试题
儿茶酚胺症引起的代谢紊乱不包括()
应具有药学专业技术职称的是应是执业药师或有药师以上专业技术职称的是
下列哪项不是围婚期保健的目的?
纵向界面管理的方法有()。
联合试运转费一般根据不同性质的项目按需要试运转车间的()计算。
按写作年代的先后顺序排列下面的课文,正确的顺序是《扁鹊见蔡桓公》、《三峡》、《范进中举》、《活板》。()
社会保障制度是通过()的办法筹集资金,国家对生活水平达不到最低标准者实行救助,对暂时或永久失去劳动能力的人提供基本生活保障,逐步增进全体社会成员的物质和文化福利,保持社会安定,促进经济增长和社会进步。
新的社会阶层是在改革开放以来社会变革中出现的,符合社会主义初级阶段社会生产力发展的要求。新的社会阶层出现的必然性是
假定你是学校英语角的会员Helen,本周五该英语角将要举行一个小型聚会。现在要求你写一个邀请函,邀请该英语角的创办者Jam教授来参加本次聚会。日期:3月12日内容包括:1.感谢他成立了英语角,给同学们提供了良好的口语练习环境;2.邀请他在本周五晚上
InsideasmallchamberataKentStateUniversitylaboratory,hamsterssleep,eat,playandrestwhilefluidflowsinandoutof
最新回复
(
0
)