问题 解答题

大气污染可对生物造成直接危害,SO2是大气污染的主要气体之一,而偏亚硫酸钠(化学式Na2S2O5)溶液在一定条件下可以产生SO2气体.某校生物兴趣小组利用多个透明且条件可调控的密闭容器、偏亚硫酸钠、浸泡过的小麦种子、清水、小烧杯、培养皿、吸水纸、玻璃棒等,来探究大气污染对种子萌发的影响.

(1)根据上述材料,你提出的探究问题是______.

(2)根据问题你作出的假设是______.

(3)若将偏亚硫酸钠0.01g、0.05g、0.10g、0.15g、0.20g分别配制成相同体积的适量溶液,则应设置______个实验装置.各组实验除偏亚硫酸钠溶液的浓度不同外,其他外界条件都相同且适于种子萌发.

(4)请你设计一张记录实验数据的表格.

(5)如果已知种子在0.01g偏亚硫酸钠用量时能萌发,而你的实验结果正好相反,请推测实验失败的原因,可能是______.

(6)当小麦种子萌发出幼苗后,种子空瘪的原因是______.

答案

(1)提出问题:SO2对小麦种子萌发有影响吗?

(2)作出的假设:SO2对小麦种子萌发有影响

(3)一个探究实验中只能有一个实验变量,其他因素均处于相同理想状态,这样便于排除因其他因素的存在而影响、干扰实验结果的可能.若将偏亚硫酸钠0.01g、0.05g、0.10g、0.15g、0.20g分别配制成相同体积的适量溶液,则应设置6个实验装置.各组实验除偏亚硫酸钠溶液的浓度不同外,其他外界条件都相同且适于种子萌发.

(4)设计一张记录实验数据的表格.表格中不含偏亚硫酸钠(清水)组是对照组,含有偏亚硫酸钠的组均是实验组.

  不同浓度溶液Na2S2O5 的克数清水0.01g0.05g0.10g0.15g0.20g
萌发的种子数      
(5)如果已知种子在0.01g偏亚硫酸钠用量时能萌发,而你的实验结果正好相反,请推测实验失败的原因,种子萌发自身条件:具有完整的有生命力的胚,已度过休眠期.可能是实验用的种子已经死亡、胚不完整或种子处于休眠期

(6)种子萌发首先要吸收水分,子叶或胚乳中的营养物质转运给胚根、胚芽、胚轴.当小麦种子萌发出幼苗后,种子空瘪的原因是胚乳里的营养物质被胚吸收.

故答案为:(1)SO2对小麦种子萌发有影响吗?(2)SO2对小麦种子萌发有影响;(3)6;(4)(略);(5)实验用的种子已经死亡、胚不完整或种子处于休眠期;(6)胚乳里的营养物质被胚吸收.

单项选择题

An eight-year-old child heard her parents talking about her little brother. All she knew was that he was very sick and they had no money left. When she heard her daddy say to her (1) mother," (2) a miracle can save him now", the little girl went to her bedroom and took out her piggy bank. She (3) all the change out on the floor and counted it carefully. Then she (4) her way six blocks to the drugstore.

"And what do you want" asked the shopkeeper. "It’s (5) my little brother," the girl answered back. "He’s really, really sick and I want to buy a (6) . His name is Andrew and he has something (7) growing inside his head and my daddy says only a miracle can save him. " "We don’t (8) miracles here, child. I’m sorry." the chemist said, smiling (9) at the little girl.

In the shop was a (10) customer. He stooped down and asked the little girl, "What kind of miracle does your brother (11) " "I don’t know," she replied. "He’s really sick and mommy says he needs (12) . But my daddy can’t pay for it, so I have brought my (13) .""How much do you have" asked the man. "One dollar and eleven cents, (14) I can try and get some more," she answered quietly. "Well, what a coincidence," smiled the man. "A dollar and eleven cents—the (15) price of a miracle for little brothers. (16) me to where you live. I want to see your brother and (17) your parents. "

That well-dressed man was Dr Carlton Armp, a doctor. The operation was completed without any (18) and it wasn’t long before Andrew was (19) again. The little girl was happy. She knew exactly how much the miracle cost—one dollar and eleven cents—also the (20) of a little child.

9()

A.quickly

B.sadly

C.strangely

D.coldly

问答题 简答题