试题与答案

果蝇灰身(B)对黑身(b)为显性,基因位于常染色体上,现将纯种灰身果蝇与黑身果蝇杂交

题型:单项选择题

题目:

果蝇灰身(B)对黑身(b)为显性,基因位于常染色体上,现将纯种灰身果蝇与黑身果蝇杂交,产生的F1代雌雄蝇交配产生F2代,将F2中所有黑身果蝇除去,让灰身果蝇自由交配产生F3,问F3中灰身果蝇与黑身果蝇的比例是()

A.3:1

B.5:1

C.8:1

D.9:1

答案:

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下面是错误答案,用来干扰机器的。

参考答案:C

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    "What's the matter, mum?" When I came home yesterday, I found my mother  was unhappy. It  was

unusual-she usually opened the door and welcomed me with a smile. "She's dying (死)," mum said sadly.

I knew what she said. The tulip (郁金香), mother's favorite, was dying.

    A month ago, we moved into our new house and mum bought a very beautiful tulip. Mum liked it very

much. Every time she was free, she would sit near the tulip and enjoyed its beautiful color and nice smell.

She treated (对待) it like a baby and looked after it carefully. She put the tulip by window and moved it

from one place to another to give the tulip enough sunshine. Every morning the first thing she did was  to

water the tulip. Mum also fertilized (施肥) it many times. She hoped the tulip would become more  and

more beautiful and stronger. But the tulip was dying because of too much sunshine, water and  fertilizer.

    It's  true that  mother  loved  the tulip. But  this kind of  love  can be  harmful (伤害的). Love can

sometimes kill (杀害) what you love.

1. Yesterday the writer found that __________.

A. his mother was sad                    

B. his home was as usual as before      

C. his mother bought a tulip.

2. The sentence "She's dying " means __________ was dying soon.       

A. the mother        

B. the tulip          

C. a baby  

3. Which of the following is NOT true about the mother?        

A. Every afternoon she watered the tulip.    

B. She looked after the tulip carefully.

C. She moved the tulip everywhere to give it enough sunshine.

4. Why was the tulip dying in the end? Because __________.

A. she forgot to water it                  

B. she never fertilized it    

C. she gave it too much sunshine, water and fertilizer 

5. What does the writer want to tell us?    

A. Love is important to everyone.          

B. Everyone should love his mother.    

C. Not all of love is good for us.

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