问题 填空题

请利用前面所学过的知识,设计实验,验证“水是绿色植物合成有机物必须的原料”

分析:实验的惟一变量是______,如何控制变量是这个实验成败的关键.

(1)先将生长旺盛的盆栽天竺葵放到______.

(2)选取两个大小相似的两个叶片作对照,其中叶片A______;另一叶片B______然后移到光下照射几小时.

(3)几小时后,摘下这两个叶片,并作如下处理:放到酒精中______漂洗叶片-加碘液-冲洗掉碘液-观察叶片变化.

实验现象:叶片A______;叶片B______.

实验结论:______.

答案

答:如何设计实验验证水是绿色植物合成有机物必须的原料呢?首先,我们要确定该探究实验的变量是水;其次要考虑如何控制实验变量.

(1)去除其它因素对实验的影响.首先考虑如何将叶片内原有的淀粉运走耗尽,可以采取暗处理的方法,即放在黑暗处一昼夜.

(2)其次要考虑如何设计以水为变量的对照实验,因为叶肉细胞进行生理活动需要的水由叶脉中的导管输送,因此可以考虑用切断叶脉的方法来控制实验变量.

(3)用酒精对实验叶片进行脱色处理后滴加碘液,观察实验现象:叶片A不变蓝,叶片B变蓝色.

(4)比较叶片A和叶片B的实验现象,我们可以得出结论:水是光合作用的原料.

故答案为:水

(1)黑暗处一昼夜

(2)于叶片基部切断主叶脉;不作处理

(3)隔水加热后

不变蓝;变蓝

水是绿色植物合成有机物必须的原料

单项选择题
阅读理解

Kerry and Alice were both artists in Britain. They taught drawing and painting at Cambridge University. Although they were friends, each thought oneself to be the better painter.

One day, Kerry promised marriage to Alice. Surprised and pleased by the offer, the girl was not sure whether she would spend her future as a wife or a painter. After a moment she replied as follows, "Each of us must paint a picture. If yours is superior to mine, you can make me your wife. If not, please drop the question." Then it was decided to give it the following day.

The next morning. Alice hung her picture on the gate. It showed a bunch of flowers and won high praise from everyone who passed by. In fact, a crowd collected in front of her masterpiece and fixed eyes on it.

Several hours passed. Then Kerry was seen coming along to the gate with what appeared to be a beautiful leather suitcase in his hand. When he finally stopped before Alice, the girl artist brushed like a rose and agreed to marry him without any hesitation. Why?

小题1:What did Alice think Kerry's offer?

A.She liked Kerry, but she didn't expect him to promise marriage to her.

B.She didn't want to marry anybody.

C.She didn't like it at all.

D.She thought the offer wasn't polite.小题2:In the sentence "If yours is superior to mine, you can make me your wife"。 "superior to" here means ____.

A.not so better than

B.better than

C.so good as

D.as good as小题3:Which of the following is true?

A.Kerry didn't accept Alice's suggestion.

B.Kerry wasn't sure of his painting so he dropped his offer.

C.Kerry did go the next day, but he failed to take a picture

D.Kerry agreed to Alice's suggestion.小题4:Alice's picture won high praise because ____.

A.it was true to nature

B.the flowers were red

C.it showed so large a bunch of flowers

D.people felt it strange to hang it on the gate小题5:The "leather suitcase" was in fact ____.

A.a real one

B.a painting drawn by Kerry

C.a box with a picture in it

D.made up of leather