问题 实验题

下面是动物细胞和细菌的结构模式图。请据图回答:

(1)一个细菌也是一个细胞。图中两种细胞相比较,相同的特点是:都有①     ,能控制物质进出细胞;②细胞质中都没有        ,不能进行光合作用。

(2)图中表示细菌结构的是       图,与动物细胞相比较,主要区别是:细菌没有成形的            

(3)在甲图中,控制生物性状的基因主要存在于图中序号       所示的结构中。

答案

(1)细胞膜;叶绿体(写“叶绿素”不扣分);(2)乙;细胞核;(3)③.

题目分析:由动物细胞和细菌的结构模式图可知:[①]细胞膜、[②]细胞质、[③]细胞核、[④]没有成形的细胞核(DNA集中的区域)、[⑤]细胞壁、[⑥]荚膜.

(1)细菌和动物细胞在结构上的相同点:都有①细胞膜、②细胞质,且细胞质中都没有叶绿体.

(2)细菌和动物细胞在结构上的不同点:细菌细胞有细胞壁,没有成形的细胞核,而动物细胞没有细胞壁,有成形的细胞核.因此,甲图是动物细胞结构模式图,乙图是细菌结构模式图.

(3)细胞核内含染色体,染色体中有 DNA,DNA是遗传信息的载体,一个DNA分子上有许多个基因.基因是染色体上具有控制生物性状的DNA片段.

单项选择题

The history of African—Americans during the past 400 years is traditionally narrated (1) an ongoing struggle against (2) and indifference on the part of the American mainstream, and a struggle (3) as an upward movement is (4) toward ever more justice and opportunity.

Technology in and of (5) is not at fault; it’s much too simple to say that gunpowder or agricultural machinery or fiber optics (6) been the enemy of an (7) group of people. A certain machine is put (8) work in a certain way—the purpose (9) which it was designed. The people who design the machines are not intent on unleashing chaos; they are usually trying to (10) a task more quickly, cleanly, or cheaply, (11) the imperative of innovation and efficiency that has ruled Western civilization (12) the Renaissance.

Mastery of technology is second only (13) money as the true measure of accomplishment in this country, and it is very likely that by (14) this under-representation in the technological realm, and by not questioning and examining the folkways that have (15) it, blacks are allowing. (16) to be kept out of the mainstream once again. This time, however, they will be (17) from the greatest cash engine of the twenty-first century. Inner-city blacks in particular are in danger, and the beautiful suburbs (18) ring the decay of Hartford, shed the past and learn to exist without contemplating or encountering the tragedy of the inner city.

And blacks must change as well. The ways that (19) their ancestors through captivity and coming to freedom have begun to loose their utility. If blacks (20) to survive as full participants in this society, they have to understand what works now.

14()

A.totolerate

B.tolerate

C.tolerated

D.tolerating

填空题 案例分析题