问题 探究题

为了探究外界因素对种子萌发的影响,某同学在四只培养皿内分别铺上相同的纸巾,再在上面分别放上等量饱满的、大小相似的大豆种子,然后放在不同的条件下培养,结果如下表。

培养皿编号
场所阳光下阳光下黑暗中阳光下
温度(℃)2020205
纸巾干湿状态潮湿干燥潮湿潮湿
发芽率90%090%0
 

请据表回答:

(1)上表的实验设计共包含了      组对照实验。

(2)在培养皿中放入一定数量的种子而不是1粒种子,其目的是                   

(3)通过上述实验,应得出的结论是        会影响种子的萌发。

(4)幼苗是由种子的       发育而来,若加入适量的营养液继续培养,几周后幼苗生长最好的是       组。

答案

(1)3   (2)避免因样本太少导致结论可靠性降低

题目分析:(1)根据分析可知此实验甲、乙两组的变量是水分,甲、丙两组的变量是光照,甲、丁两组的变量是温度,乙、丙两组变量是水分和光照,乙、丁两组变量是温度、水分,丙、丁两组变量是温度、光照,因此上述表格中有3组对照试验,变量分别是水分、光照、温度。

(2)培养皿放入一定数量种子,因为这样可以减少其他因素的影响而导致的误差.因此用多粒种子做实验是为了可增加实验的可靠性,排除偶然性,增强实验的准确性。

(3)甲组种子温度适宜20度、潮湿(有适量的水),有充足的空气,因此种子萌发;乙组种子由于缺少一定量的水分所以不萌发;丙组种子尽管处在黑暗中,种子照样萌发;丁组种子由于温度太低不萌发.根据实验结果,得出的结论是水分和温度会影响种子的萌发,光照不影响种子的萌发.

(4)种子萌发时,吸水膨胀,种皮变软,呼吸作用逐渐增强,储存在子叶或胚乳内的营养物质逐步分解,转化为可被细胞吸收利用的营养物质,输送给胚芽、胚轴、胚根.种子的胚根首先突破种皮,向地生长,并发育为幼苗的根,随后胚轴的细胞也相应生长和伸长,发育成根与茎的连接部分,胚芽发育成幼苗的茎和叶,与此同时,贮存养料的胚乳或子叶由于营养物质被消耗而逐渐萎缩,可见胚是发育幼苗的结构,甲组种子具有种子萌发的外界条件:适宜的温度、适量的水分和充足的空气,因而能够萌发,还具有植物进行光合作用的条件光,因而若加入适量的营养液继续培养,能够很好的生长。

选择题
完形填空
完形填空
     We often talk about ourselves as if we have permanent genetic defects(缺陷)that can never be
changed."I'm impatient.""I'm always behind.""I always put things off!"You've surely heard them.Maybe
you've used them to describe yourself.
     These comments may come from stories about us that have been __1__ for years-often from as far
back as childhood.These stories may have no __2__ in fact.But they can set low expectations for us.As a child,my mother said to me,"Marshall,you have no mechanical skills,and you will never have any
mechanical skills for the rest of your life."How did these expectations __3__ my development?I was never __4__ to work on cars or be around __5__.When I was 18,I took the US Army's Mechanical Aptitude
Test.My scores were in the bottom for the entire nation!
     Six years later,__6__,I was at California University,working on my doctor's degree.One of my
professors,Dr. Bob Tannbaum,asked me to write down things I did well and things I couldn't do.On the
positive side,I __7__ down,"research,writing,analysis,and speaking."On the __8__ side,I wrote,"I have no mechanical skills."
     Bob asked me how I knew I had no mechanical skills.I explained my life __9__ and told him about my __10__ performance on the Army test.Bob then asked,"Why is it that you can solve __11__ mathematical problems,but you can't solve simple mechanical problems?"
     Suddenly I realized that I didn't __12__ from some sort of genetic defect.I was just living out
expectations that I had chosen to __13__.At that point,it wasn't just my family and friends who had been
__14__ my belief that I was mechanically hopeless.And it wasn't just the Army test,either.I was the one
who kept telling myself,"You can't do this!"I realized that as long as I kept saying that,it was going to
remain true.On the contrary,if we don't treat ourselves as if we have incurable genetic defects,we can
__15__ well in almost anything we choose.
( )1. A. said        
( )2. A. basis      
( )3. A. lead        
( )4. A. encouraged  
( )5. A. means      
( )6. A. therefore  
( )7. A. settled    
( )8. A. passive    
( )9. A. experiences
( )10. A. unexpected
( )11. A. complex    
( )12. A. arise      
( )13. A. believe    
( )14. A. weakening  
( )15. A. do        
B. spoken        
B. plot          
B. improve      
B. demanded      
B. tools        
B. somehow      
B. turned        
B. active        
B. trips        
B. poor          
B. advanced      
B. separate      
B. suspect      
B. strengthening
B. go            
C. spread      
C. cause      
C. affect      
C. hoped      
C. facilities  
C. instead    
C. took        
C. negative    
C. roads      
C. excellent  
C. common      
C. suffer      
C. adopt      
C. abandoning  
C. work        
D. repeated  
D. meaning    
D. change    
D. agreed    
D. hammers    
D. however    
D. got        
D. subjective
D. paths      
D. average    
D. primary    
D. come      
D. receive    
D. accepting  
D. get