问题
单项选择题
某植物种群AA基因型个体占30%,aa基因型个体占20%,该种群的A和a基因频率分别是()。
A.30%、20%
B.45%、55%
C.50%、50%
D.55%、45%
答案
参考答案:D
解析:种群中,AA基因型个体占30%,aa基因型个体占20%,Aa占1-(30%+20%)=50%。A的基因频率为30%+50%/2=55%。a的基因频率为1-A=1-55%=45%。
某植物种群AA基因型个体占30%,aa基因型个体占20%,该种群的A和a基因频率分别是()。
A.30%、20%
B.45%、55%
C.50%、50%
D.55%、45%
参考答案:D
解析:种群中,AA基因型个体占30%,aa基因型个体占20%,Aa占1-(30%+20%)=50%。A的基因频率为30%+50%/2=55%。a的基因频率为1-A=1-55%=45%。
One Monday morning,news got around in the schoolyard about a fire over the weekend.Soon Mr.Johnson,my teacher,came to explain that the Art class would be ____ due to the fire.He also warned us not to approach the Art room because it could be ____. During the morning break,Kirn and I decided to take a ____.A first hand observation would make us heroes at lunch.At the appointed time,Kirn and I ____ the Art room,ignoring the consequence I would face ____ I got caught.We stood on tiptoes looking hard ___ the door window,trying in vain to see ____ was forbidden.Suddenly a firm __ on our shoulders stopped us. Turning around,I found a teacher staring angrily at us.In those seconds millions of ___ flashed through my mind.My father would beat me hard.____ than that,my mom might be so mad that she might not stop him.My spirits ____ even lower while realizing how ____ Mr.Johnson would be. When Kirn and I were led back to our classroom,I could found ____ to hide and wanted to melt into the ____.However,Mr.Johnson had a different ___ to teach. Slowly,he bent down to look me in the ____,and I was met with a look of concern rather than anger.He spoke softly as he explained why he was ____ in my decision to go where I may have got hurt.He cared more about my ____ than the fact that I’d broken a rule.My heart was ___ with regret,and I discovered that he still loved me even after I disappointed him.The rest of the day,he didn’t even mention it in class publicly,___ did he tell my parents.It was the first time I felt the power of being given an unexpected second chance.
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