问题 单项选择题

骨骼肌收缩过程中作为钙受体的蛋白是

A.肌球蛋白
B.肌动蛋白
C.肌钙蛋白
D.原肌球蛋白

答案

参考答案:C

解析:①横桥头部具有ATP酶活性,在肌肉处于舒张状态时,横桥结合的ATP被分解,分解产物ADP和无机磷酸仍留在头部,此时的横桥处于高势能状态,其方位与细肌丝垂直,并对细肌丝中的肌动蛋白有高度亲和力,但并不能与肌动蛋白结合,因为肌丝上肌钙蛋白与原肌球蛋白的复合物遮盖了肌动蛋白的活化位点。②当胞质内Ca2+浓度升高时,肌钙蛋白与Ca2+结合并发生构象变化,这种变构导致肌钙蛋白与肌动蛋白的结合减弱,使原肌球蛋白向肌动蛋白双螺旋沟槽的深部移动,从而暴露出肌动蛋白的活化位点,使肌球蛋白头部与肌动蛋白结合。③肌动蛋白与横桥头部的结合造成横桥头部构象的改变,使头部向桥臂方向摆动45°,并拖动细肌丝向M线方向滑动,从而将横桥头部贮存的能量(来自ATP的分解)转变为克服负荷的张力和(或)肌丝滑动引起的肌节缩短。在横桥头部发生变构和摆动的同时,ADP和无机磷酸便与之分离。④在ADP解离的位点,横桥头部结合一个ATP分子,结合ATP后,横桥头部对肌动蛋白的亲和力明显降低,遂使它与肌动蛋白解离。⑤解离后的横桥头部迅速将与其结合的ATP分解为ADP和无机磷酸,并恢复垂直于细肌丝的高势能状态。如果此时胞质内Ca2+浓度较高,横桥头部便又可与下一个新的肌动蛋白活化位点结合,重复上述收缩过程。

阅读理解

You finish a workout and feel great. Then you get up the next morning and your exercised muscles feel sore. You find it hard to lift your arms and brush your teeth, or bend down to pick up a book. What has happened?

Scientists call this soreness 24 to 48 hours after your exercise “delayed onset (延迟发作) of muscle soreness”, or DOMS. It is caused by microscopic damage to muscle fibers, which releases chemicals. The chemicals irritate (刺激) nerve fibers and cause pain.

Muscle soreness is a good sign. It means that you have challenged your muscles and are getting stronger. Everyone experiences it, even the best athletes. But it can be avoided by using the right exercise methods. Here are some tips:

* Warm up before you work out. This is helpful to avoid muscle soreness, but more importantly to avoid injury. It starts circulation to the muscles and warms the muscles and tendons, getting them ready for exercise.

* Stretch after your workout. After exercising, make sure you stretch your muscles for 15 to 20 seconds before they cool down. They will be warm and elastic (弹性的) so they will stretch well.

* Don’t do too much too soon. Whether it’s jogging, running, whatever workout routine you are starting, just do half of the exercise volume the first week to introduce your muscles to the exercises.

If you are already feeling muscles soreness, here are some ways to help relieve it.

* Get a massage (按摩). Lightly massage the sore muscle and gradually increase the depth of the massage. It might be painful in the beginning but it will gradually ease the muscle soreness.

* Take a hot bath. Nothing beats a long soak in a hot bath for muscle soreness. The heat will increase circulation and provide a soothing (舒缓) effect.

* Flush your muscles. Run hot (as hot as you can bear) water over the sore muscles for two minutes and then immediately switch to cold water for 30 seconds. Repeat this process five times. This has the effect of opening and closing your blood vessels (血管). It will flush the acid (酸物质) from them and ease the soreness.

* Exercise gently. Go for a slow walk and breathe deeply. This helps reduce muscle soreness by increasing blood flow to the sore muscles.

72. What is the purpose of this article?

A. To tell readers to exercise more for fitness.

B. To warn readers of the side effects of exercise.

C. To give readers advice on how to avoid and relieve muscle soreness.

D. To introduce good forms of exercise.

73. The article suggests that before exercise we should ______.

A. stretch our muscles                   B. have a massage

C. have a hot shower                   D. warm up our muscles

74. From this article we can conclude that muscle soreness is caused by ______.

A. damaged muscle fibers               B. damaged nerve fibers

C. a bad circulation to the muscles        D. exercise injuries

75. Judging from the article, which of the following statements is TRUE?

A. Only beginners get muscle soreness.

B. Muscle soreness means you have physical problems and should stop exercising.

C. Muscle soreness is a good sign because it means that the muscles are getting stronger.

D. Muscle soreness can be relieved by increasing the amount of exercise.

阅读理解与欣赏

阅读下面文字,完成下面的题。 

应   聘

李桂芳

  ①母亲陪着儿子来人才市场应聘。看那儿人山人海的,母亲就有了许多焦虑。无论如何她得帮儿子找到工作。 

  ②儿子大学毕业后,已经在家待了半年。他的同学陆陆续续找到了称心如意的工作,可儿子老是不慌不忙的,说工作迟早会有的。为这,母亲真有些生气了,所以今天非得亲自陪着儿子来应聘不可。 

  ③终于看中了一份待遇不错的推销工作,儿子的条件也挺适合的。母亲便努力地挤进密密匝匝的人群里去,好不容易帮儿子要到了一张应聘报名表。儿子接过表格,三两下就填完了。母亲接过一看,字迹很是潦草,就生气地说,你怎么这样,不能把字写好点儿吗?儿子不耐烦地说,我就那水平。 

  ④母亲无奈地再次挤到了前台,又要了一张表格。看看拥挤的人流,害怕挤出去难以再挤进来交表,便靠着工作台,拿笔填起来。母亲的字写得很漂亮,她的书法作品曾在中学时得过奖。一个工作人员见她正专心地填表,凑过来,看了看说,不是你应聘吧?母亲被身后的人流推得歪来倒去的,好不容易站稳了,连忙说,不是的,我是给我儿子填的。那人说,你儿子本人呢?母亲不好意思地笑了笑说,他力气小,挤不进来。工作人员看了母亲写的字说,你的字写得不错嘛。母亲赶紧说,我儿子写得还要好呢。 

  ⑤因为表格交在前面,不多时就叫到了儿子的名字,母亲赶紧大着嗓门儿朝后面叫儿子的名字。儿子好半天才挤到前面,边挤边抱怨说,让你别忙,你忙什么呀?母亲朝他使使眼色,把他拉到工作人员面前。 儿子被叫到另外一间小屋进行面试,母亲赶忙跟了进去。工作人员问儿子,你为什么要来应聘这份工作?刚才还和母亲顶嘴的儿子,此时突然紧张起来,好半天才挤出一句话说,我需要找份工作。母亲赶忙帮他圆场说,我儿子从小就伶牙俐齿的,这会儿是紧张了点儿。他适合做这个推销工作的。你别看这孩子长得瘦,很能吃苦的。小时候吧,家里的一切家务活儿他都承包了,街坊四邻一个劲儿夸他能干呢。 

  ⑥工作人员又问了一个问题,你觉得做推销工作需要具备怎样的素质?儿子想了半天,大冷的天,额上冷汗直冒,半天才张嘴说,我觉得只要能吃苦就行。母亲嗔怪地看了儿子一眼,连忙接过他的话头说,这孩子,刚才在路上还给我说得头头是道呢,这会儿就忘了?母亲对工作人员说,搞推销,一直是我儿子的梦想,所以,一直以来他都有意识地在培养这方面的能力。他平时就跟我说,推销人员应该有以下素质:一是有一副好口才,能为产品做详细生动的口头广告;二是有吃苦精神,能走街串巷,不怕麻烦地上门服务;三是有良好的交际能力,能和各色各样的人打交道,广泛地推销产品……母亲一口气说了十点,毫不停歇,好多竟是工作人员从没听过的有价值的新观点。

  ⑦听完母亲的介绍,在场的人都面露微笑。母亲一看他们的微笑,心里就跟喝了蜜似的甜。她知道儿子的工作终于有希望了,于是欢天喜地地领着儿子回家等候通知。 

  ⑧三天后,母亲终于等来了那家公司的电话,她非常高兴,儿子也十分兴奋。然而,听过电话,母亲却呆了…… 

                       (选自《儿童文学》2011年第8期)

1.文中的母亲在应聘中帮儿子做了哪几件事?请简要概括。

答:                                                                                    

2.结合上下文,品析下列句中加粗词的表达效果。

(1)儿子好半天才挤到前面,边挤边抱怨说……

答:                                                                                   

(2)母亲嗔怪地看了儿子一眼,连忙接过他的话头……

答:                                                                                    

3.文中应聘的结果可能有以下三种,选择你认为最有可能出现的一种,并说说理由。

A.被录取的是母亲

B.儿子没被录取

C.儿子和母亲都被录取了

答:_________________________                ________

4.你对“母亲陪儿子去应聘”这种现象有什么看法?请结合内容阐述理由。

答: