问题 选择题

在生物化学反应中,当底物与酶的活性位点形成互补结构时,可催化底物发生变化,如下图Ⅰ所示。竞争性抑制剂与底物竞争酶的活性位点,非竞争性抑制剂和酶活性位点以外的其他位点结合,从而抑制酶的活性,如下图Ⅱ、Ⅲ所示。癌症化疗时应用的烷化剂(如二氯二乙胺)能够阻止参与DNA复制的酶与DNA相互作用。下列图示与此机制相符的是

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A.Ⅰ

B.Ⅱ

C.Ⅲ

D.Ⅰ、Ⅱ、Ⅲ

答案

答案:C

阅读理解

Since we are social beings,the quality of our lives depends in large measure on our interpersonal relationships.One strength of the human conditions is our possibility to give and receive support from one another under stressful (有压力的) conditions.Social support consists of the exchange of resources among people based on their interpersonal ties.Those of us with strong support systems appear better able to deal with major life changes and daily problems.People with strong social ties live longer and have better health than those without such ties.Studies over types of illnesses,from depression to heart disease,show that the presence of social support helps people defend themselves against illness,and the absence of such support makes poor health more likely.

Social support cushions stress in a number of ways.First,friends,relatives and co­workers may let us know that they value us.Our self­respect is strengthened when we feel accepted by others in spite of our faults and difficulties.Second,other people often provide us with informational support.They help us to define and understand our problems and find solutions to them.Third,we typically find social companionship supportive.Taking part in free­time activities with others helps us to meet our social needs while at the same time distracting (转移注意力) us from our worries and troubles.Finally,other people may give us instrumental support—money aid,material resources,and needed services—that reduces stress by helping us resolve and deal with our problems.

小题1:Interpersonal relationships are important because they can________.

A.deal with life changes

B.smooth away daily problems

C.make people live more easily

D.cure types of illnesses小题2:The researches show that people’s physical and mental health________.

A.has much to do with the amount of support they get from others

B.lies in the social medical care systems which support them

C.depends on their ability to deal with daily worries and troubles

D.is related to their courage for dealing with major life changes.小题3:Which of the following is closest in meaning to the underlined word “cushions”?

A.takes place of    

B.makes up of

C.lessens the effect of 

D.gets rid of小题4:Helping a sick neighbor with some repair work in spare time is an example of________.

A.instrumental support

B.informational support

C.social companionship

D.the strengthening of self­respect小题5:What is the subject discussed in the text?

A.Effects of stressful conditions.

B.Kinds of social support.

C.Ways to deal with stress.

D.Interpersonal relationships.

单项选择题 A1/A2型题