问题 解答题

①肠道病毒EV71是人肠道病毒的一种,常引起儿童手足口病、病毒性咽峡炎,重症患儿可出现肺水肿、脑炎.

②炭疽病是由炭疽杆菌引起的一种传染病.牛、马、羊等食草性牲畜最容易得此病,主要症状是高热、黏液紫黑、呼吸困难,常常来不及医治而亡,给农牧业带来严重损失.

请分析资料回答下列问题:

(1)从侵染细胞的不同上看,病毒EV71属于______病毒;病毒EV71结构简单,仅由______和______组成.

(2)病毒EV71必须寄生在其他生物的活细胞内才能生活和繁殖,它是以______方式进行繁殖的.

(3)与牛、马、羊等动物的细胞相比,炭疽杆菌细胞在结构上的主要特点是______.

(4)一般情况下,炭疽杆菌可通过______的方式繁殖后代.用煮沸的方法无法消灭炭疽杆菌,主要是由于炭疽杆菌会产生______.

答案

(1)病毒没有细胞结构,由蛋白质外壳和遗传物质(核酸)组成,肠道病毒EV71是人肠道病毒的一种,属于动物病毒.

(2)病毒必须寄生在活细胞里,靠自己的遗传物质中的遗传信息,利用细胞内的物质,制造出新的病毒.离开了活细胞,通常变成结晶体.

(3)炭疽杆菌是一种细菌,细菌细胞在结构上的主要特点是没有成形的细胞核.

(4)细菌的繁殖方式是分裂繁殖.当环境变的不利于细菌生长时,细菌能够形成一个椭圆形的休眠体,叫做芽孢,芽孢对干旱、低温、高温等恶劣环境有很强的抵抗力,故煮沸的方式无法消灭炭疽杆菌.

故答案为:(1)动物;蛋白质外壳;内部遗传物质

(2)自我复制

(3)无成形的细胞核

(4)分裂;芽孢

单项选择题
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     I am truly saddened about what is going on in my school district, especially in the school where I am

currently working.

     Why are so many students not doing well? Why is there such a huge achievement gap between urban

and suburban students? Just this week, in my school the seventh grade team leader called a meeting to

discuss academic detention (放学后留校). The purpose of the detention is to allow students who are

doing poorly a second chance to redo the work. Now if a student did not understand an assignment I have no trouble allowing that student to redo a test or give some extra credit work, but if a student did poorly

because he/she opted(选择) not to do the work out of sheer laziness, that student should not be given a 

second chance.

     And parents should be held accountable for their children. That is another reason why there is such a

huge achievement gap. All children should be monitored at home in order to achieve great success in

school. Perhaps it might be a great idea for urban school districts to offer free classes to parents on how to help their students at home. Of course this idea is far fetched, after all we do not want to offend the

parents. What we will do instead is to spend a fortune on teacher training because if the kids are not doing well it must be the fault of the teacher. That kind of mindset, if allowed to continue will be a perfect recipe

for greater achievement gaps.

      I started working at my current school in August and I have been in the teaching field for 25 years.

What I believe is that you can lead a horse to water but you can't make that  horse drink. You can't force kids to change bad habits over  night, nor can we afford to lower standards just so a kid can  pass a class.

1. The seventh grade team leader in the author's school called    a meeting to ________.

A. analyse the reason for the huge achievement gap between students

B. find out who is to blame for the huge achievement gap between students

C. talk about giving students who are doing poorly a second  chance to redo the work

D. discuss how to narrow the huge achievement gap between students

2. The author believes that a student can be given a second chance ________.

A. if he did poorly the first time

B. for whatever reason he did poorly the first time

C. if he failed the first time in spite of his efforts

D. if he comes from a suburban area

3. In the last paragraph, the author intends to tell us that ________.

A. a student can make improvement only when he is willing to

B. teachers are to blame if his students are doing poorly

C. the school should force those students to work harder if   they're doing poorly

D. the school should treat different students with different standards