问题 探究题

(8分)某生物小组以天竺葵为材料进行了有关光合作用的实验探究,实验过程如下图所示,请回答问题:

(1)该实验的正确操作顺序是__________________________。(填图中序号)

(2)图中③是把叶片放入盛有______________的小烧杯里隔水加热,使叶片里的________________溶解到这种液体里。

(3)图中④的目的是__________________________________。

(4)图中②叶片先用清水漂洗,然后滴加碘液染色,来检验是否有光合作用的产物______________生成。本实验中叶片上被黑纸遮盖部位_____________(变蓝、不变蓝),未被黑纸遮盖部位__________________(变蓝、不变蓝),说明光合作用需要________________。

答案

(1)①④③② (2)酒精 叶绿素(3)把叶片中的淀粉全部转运和消耗(4)淀粉 不变蓝 变蓝 光

题目分析:(1)该实验的方法步骤:暗处理→遮盖后,光照射→几小时后摘下叶片→酒精脱色→漂洗,加碘液→冲洗观察叶色现象,所以顺序是①④③②;

(2)把叶片放入盛有酒精的小烧杯中,隔水加热,目的是用酒精溶解叶片中的叶绿素,叶片变成黄白色,便于观察到淀粉遇碘变蓝的颜色反应,装有酒精和叶片的小烧杯,一定要隔水加热,这是因为酒精是易燃、易挥发的物质,直接加热容易引起燃烧发生危险,使用水对酒精进行加热,起到控温作用,以免酒精燃烧发生危险;

(3)暗处理:把盆栽的天竺葵放到黑暗处一昼夜,目的是让天竺葵在黑暗中把叶片中的淀粉全部转运和消耗,这样实验中用碘液检验的淀粉只可能是叶片在实验过程中制造的,而不可能是叶片在实验前贮存;

(4)分析现象,得出结论:叶片见光(未遮盖)部分,遇碘变蓝,说明叶片见光部分进行光合作用,产生淀粉,叶片遮光部分,遇碘不变蓝,说明光是绿色植物制造有机物不可缺少的条件。

单项选择题

The girls in this sixth grade class in East Palo Alto, California, all have the same access to computers as boys. But researchers say, by the time they get to high school, they are victims of what the researchers call a major new gender (性别) gap in technology. Janice Weinman of the American Association of University Women says, "Girls tend to be less comfortable than boys with the computer. They use it more for word processing rather than for problem solving, rather than to discover new ways in which to understand information."

Girls often feel ______.
A. bored with computer games
B. comfortable using computers
C. it hard to use computers in word processing
D. worried about using computers

After re-examining a thousand studies, the American Association of University Women researchers found that girls make up only a small percentage of students in computer science classes. Girls consistently rate themselves significantly lower than boys in their ability and confidence in using computers. And they use computers less often than boys outside the classroom.An instructor of a computer lab says he’s already noticed some differences. Charles Cheadle of Cesar Chavez School says, "Boys are not so afraid they might do something that will harm the computer, whereas girls are afraid they might break it somehow."
Six years ago, the software company Purple Moon noticed that girls’ computer usage was falling behind boys. Karen Gould says, "The number one reason girls told us they don’t like computer games is not that they’re too violent, or too competitive. Girls just said they’re incredibly boring."
Purple Moon says it found what girls want, characters they can relate to and story lines relative to what’s going on in their own lives. Karen Gould of Purple Moon Software says, "What we definitely found from girls is that there is no intrinsic (固有的) reason why they wouldn’t want to play on a computer; it was just a content thing."
The sponsor of the study says it all boils down to this: the technology gender gap that separates the girls from the boys must be closed if women are to compete effectively with men in the 21st century.

判断题