问题 单项选择题

下列关于细胞分子组成的阐述错误的是()

A.生物群落与无机环境间的循环物质是指构成细胞的各种化合物

B.中心法则涉及的DNA、RNA、蛋白质分子既具有多样性、又具有特异性

C.多糖一定是非还原糖,单糖、二糖不一定是还原糖

D.叶绿体中的化合物组成比核糖体、染色体复杂得多

答案

参考答案:A

解析:

生物群落与无机环境间的循环物质是指构成细胞的各种元素而不是各种化合物,所以A错误;DNA分子既有多样性又有特异性,由其控制合成的RNA、蛋白质也就有了多样性和特异性;所以B正确;多糖一定是非还原糖,单糖中一些是还原糖,二糖不一定是还原糖如蔗糖,所以C正确;核糖体是由RNA和蛋白质组成,染色体由DNA和蛋白质组成,而叶绿体是光合作用的场所,其含有色素、各种酶、膜成分等,比核糖体和染色体的组成复杂的多,所以D正确。

考点:本题考查细胞的分子组成的内容,意在考查考生对所学知识的理解和掌握

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     For a while, my neighbourhood was taken over by an army of joggers(慢跑者 ) . They  were  there  

all  the  time : early  mornings, noons,and evenings. There were little old ladies in gray sweats, young

couples in Adidas shoes, middle-aged men with red faces. "Come on !" My friend Alex encouraged me

to join him as he jogged by my house every evening. " You'll feel great. "

      Well,  I had nothing against feeling great and if Alex could jog every day, anyone could. So I took up

jogging seriously and gave it a good two months of my life, and not a day more. Based on my experience,

jogging is the most overvalued form of exercise around, and judging from the number of the people who

left our neighbourhood jogging army,l'm not alone in my opinion.

      First of all ,jogging is very hard on the body. Your legs and feet take a  real pounding (重击) running  down  a  road  for  two  or  three miles. I developed foot,leg, and back problems. Then I read about a

nationally famous jogger who died of a heart attack while jogging,

and I had something else to worry about. Jogging doesn't kill hundreds of people, but if you have any

physical weaknesses,jogging will surely bring them out , as they did with me.

     Secondly,  I got no enjoyment out of jogging. Putting one foot in front of the other for forty-five minutes

isn' t my idea of fun. Jogging is also a lonely pastime. Some joggers say, " I love being out there with just

my thoughts. " Well, my thoughts began to bore me, and

most of them were on how much my legs hurt.

      And how could I enjoy something that brought me pain? And that wasn't just the first week : it was

practically every day for two months. I never got past the pain level, and pain isn't fun. What a cruel  way 

 to  do  it !  So  many  other exercises , including  walking , lead

to almost the same results painlessly , so why jog?

       I don't jog any more , and  I  don't think  I  ever will. I'm walking two miles three times a week at a

fast pace, and that feels good. I bicycle to work when the weather is good. I'm getting exercise, and I'm

enjoying it at the same time. I could never say the same for jogging,and I've found a lot of better ways to

stay in shape.

1. From the first paragraph, we learn that in the writer's neighbourhood ___________. 

A. jogging became very popular

B. people jogged only during the daytime

C. Alex organized an army of joggers

D. jogging provided a chance to get together

2. The underlined word "them" ( Paragraph 3) most probably refers to _________.

A. heart attacks                

B. back problems

C. famous joggers                

D. physical weaknesses

3. What was the writer's attitude towards jogging in the beginning? 

A. He felt it was worth a try.

B. He was very fond of it.

C. He was strongly against it.

D. He thought it must be painful.

4. Why did the writer give up jogging two months later? 

A. He disliked doing exercise outside.

B. He found it neither healthy nor interesting.

C. He was afraid of having a heart attack.

D. He was worried about being left alone.

5. F'rom the writer's experience,we can conclude that________. 

A. not everyone enjoys jogging

B. he is the only person who hates jogging

C. nothing other than jogging can help people keep fit

D. jogging makes people feel greater than any other sport

单项选择题