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、Provide extra energy to start the reaction. B、Raise the temperature of the chemicals. C、Release a chemical needed to start the
A、Provide extra energy to start the reaction. B、Raise the temperature of the chemicals. C、Release a chemical needed to start the
admin
2013-12-14
41
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、Provide extra energy to start the reaction.
B、Raise the temperature of the chemicals.
C、Release a chemical needed to start the reaction.
D、Lower the amount of energy needed to start the reaction.
答案
D
解析
酶可以极大减少发生反应所需的能量。
转载请注明原文地址:https://jikaoti.com/ti/c0NDFFFM
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
Itusedtobethatacorporation’scapitalconsistedoftangibleassetssuchasbuildings,machines,andfinishedgoods.But,
Thetruthmaywellbeself-evidentthatallhumansarecreatedequal,butonethingourMakerdidnotendowuswithequallyist
Weareallmembersofaculture.Howweinterprettherealityaroundus,whatweconsidertobereasonablestatementsandbehavi
A、Theassistantsmustknowtheirnames.B、Theytellwhattheirmajorsare.C、Toomanynon-studentsusethelab.D、Thecomputers
Thedoctorsuggeststhatagoodholidayinthecountryshould______him______nicelyafterhisoperation.
Seanalivedintheinpatienthospiceunitformorethanamonth,farlongerthananyonewouldhavepredicted,sustainedonlyon
Althoughspeechandwritingarethespecialmeansofcommunicatingofhumans,theinterchangealsotakesplaceinmanyotherway
Youcanhavetoomuchofagoodthing,itseems—atleastwhenitcomestophysiotherapyafterastroke.Manydoctorsbelievetha
Surely,itwouldbesensibletogetasecondopinionbeforetakinganyfurtheraction.
A、Anormalbabyrespondedtothestimuliimpassively.B、Anormalbaby’sreactiontothesoundwasphlegmatic.C、Agroupofnurse
随机试题
某企业2008年息税前利润为200万元,企业资产总额为1000万元,资产负债率为40%,负债资金平均年利率为10%。企业没有优先股和租赁费用。要求:(1)计算企业2008年利息费用;(2)计算企业财务杠杆系数。(注:计算结果保留小数点后两位)
男,56岁,左小腿轻度肿胀,有多条蚓状血管团,其内有硬结,症状逐年加重,如不进行治疗,其最严重的后果是
眶距增宽症常见术后并发症不包括以下哪一项
用成本计算估价法计算国产非标准设备原价时,利润的计算基数中不包括的费用项目是()。【2006年真题】
以课程任务为依据进行分类,课程可分为()。
6,7,18,23,38,()。
设周期为4的函数f(x)处处可导,且,则曲线y=f(x)在(-3,f(-3))处的切线为______.
设随机变量X与Y相互独立,且X服从区间[-1,2]上的均匀分布,y的分布律为Y~,则概率P{X<Y}=
在VisualFoxPro中,程序中不需要用PUBLIC等命令明确声明和建立,可直接使用的内存变量是()。
设有订单表order(订单号,客户号,职员号,签订日期,金额),查询2011年所签订单的信息,并按金额降序排序,正确的SQL命令是( )。
最新回复
(
0
)