问题 单项选择题

患者,男性,55岁,1年前出现动作不灵活,动作困难和缓慢,左上肢震颤,静止时明显,动作时减轻,入睡后消失

根据病人情况,患者可能的病因是

A.遗传

B.多巴胺受体减少

C.乙酰胆碱(Ac的兴奋性减弱

D.迷走神经的兴奋

E.农业毒素

答案

参考答案:B

阅读理解

阅读理解。

Wendy: What do you want to be when you grow up?

Arnold: A police officer. I want to ride around in a police car and catch bad guys all day,

Wendy: Won't you be scared?

Arnold: No, because I'll have my police dog with me. And I'll have a partner. Hey, you can be my partner!

Wendy: No,thanks.

Arnold: That's OK. I'll still call you on my police radio.

Wendy: Cool! But you'd better call me before 9:00 pm.  That's my bed time.

Arnold: So, what do you want to be?

Wendy: I don't know, maybe a nurse ...or a pilot ...or a scientist.

Arnold: You want to do all of those things?

Wendy: No, only one. I'm just not sure which one.

Arnold: Still, you'll have to go to college.

Wendy: That's fine. My mom and dad went to the same college in Miami. I want to go there, too.

Arnold: Don't you hate school?

Wendy: No, I think it's all right. How about you?

Arnold: Yeah, I guess it's not too bad. Hey, do you think I can go to college?

Wendy: If you try hard, you can do anything you want.

1. Arnold is _____ about his future dream.

    A. not sure          

    B. quite sure    

    C. undecided    

    D. confused

2. Wendy doesn't want Arnold to          .

    A. be a police officer    

    B. have a dog    

    C. go to sleep      

    D. call her late at night

3. What job is Wendy uninterested in?

    A. A police officer.        

    B. A nurse.      

    C. A scientist.      

    D. A pilot.

4. Why does Wendy want to go to school in Miami?

    A. It's a good school.                

    B. Her parents went there.

    C. It's near her house.                

    D. Arnold wants to go there.

5. Which of the following is TRUE?

    A. Wendy doesn't want to go to college.      

    B. Arnold doesn't like school.

    C. Wendy's mom and dad went to different schools.    

    D. Wendy isn't sure about her future.

单项选择题

阅读以下文字,完成1~4题。

人类生命的信息是怎样传递的呢对它的研究关系到生命本质、疾病的发生及防治等一系列重大问题的解决。生命的维系和生命的活动正常进行的根本条件,是细胞间以各种方式进行的通信。细胞间的通信要通过细胞问的信息传递来完成,即由信息细胞释放第一个信使、经细胞外液去影响和作用于其他信息接收细胞。第一信使并不直接参与细胞的物质和能量代谢,而是将信息传递给第二信使,转而调节细胞的生理活动和新陈代谢。

第一信使是指激素、神经递质、细胞因子及生长因子等胞外小分子信息物质,起着传递生命信息指令的作用。

第二信使是指环磷酸腺苷(Camp)和环磷酸鸟苷(Cgmp),为生命信息的转换机构,把第一信使效应的信号由细胞膜进一步传向细胞内,起到接收和放大的作用。

第一信使首先作用靶细胞膜上相应的受体,并与其结合,再经G蛋白等信号转换机构的作用,将外来的化学信号转换成细胞内的调节信号,以维持细胞的正常生活功能。

G蛋白家族起着将受体的信息传递给效应物的作用,直接参与对离子道的调节。离子道是镶嵌在膜上的跨膜蛋白质,为细胞代谢和生命活动之门。跨膜传递激发的酶促反应引起膜电位的改变,导致离子道的开放或关闭,从而影响离子物质的通过。

当第一信使配体与相应受体结合后,诱发受体分子构象改变,G蛋白把受体和环化酶偶联在一起,并控制该酶活性,进而影响第二信使的生成。第二信使作为细胞新的信号,激活相应的蛋白激酶,再通过蛋白质磷酸化等一系列酶促反应,调控细胞的活动。

第二信使系统不仅执行了传递激素等信息的使命,而且构成了这种信息的二级放大系统,使被处理的信息成万倍地扩大,以至几个分子的第一信使小分子物质就可以使细胞产生显著的生理效应。

下列对“第二信使”的传输机理,理解正确的一项是()。

A.第二信使作为生命信息的转换机构,将接收到的第一信使,由细胞膜传向细胞内

B.第二信使作为生命信息的转换机构,将外来的信号转换成细胞内的调节信号,从而调节细胞的生理活动

C.第二信使作为细胞新的信号,转变成相应的蛋白激酶,促使蛋白质磷酸化,进而调控细胞的活动

D.第二信使在接收激素等信息以后,又将该信息改变并放大,使被改变的信息成万倍地扩大