人教版八年级下册英语周报2020－2021答案

2门1,则证明控制花色的基因具有显性纯合致死效应。22.(13分,除标注外每空2分)(1)aabb1/6(2)花色显性(3)利用红色宽叶植株自交后代发生性状分离,组分离比接近于2:1(3分)【解析】(1)根据F1的性状分离比为6:2:3:1(9:3:3:1的变形)可知,这两对基因的遗传遵循自由组合定律,则亲本基因型为AaBb,子代的表现型和基因型为红色窄叶AaBB、AaBb,红色宽叶Aabb,白色窄叶aBB、aaBb,白色宽叶abb,故F1中纯合子只有aBB和abb,所占比例为1/12+1A12=1/6。(2)由分析可知,A这对等位基因显性纯合时会使」受精卵致死,说明控制花色的基因具有显性纯合致死效应。(3)①为验证(2)中的推测,最简便的方法是让F1中红色宽叶植株自交,统计子代的表现型及比例如果后代出现性状分离比,且红色与白花之比接近

第三节One possible version:Paragraph 1One night afier the museum closes, Maria appears atthe gate of the museum. She enters the building quietlyusing the security code that Max shared with her. Whendealing with a beautiful woman, men can be so stupid,she laughs to herself. She sneaks into the jewelry exhibitand destroys the alarms. Then she walks up to the glasscase protecting the Black Diamond and unlocks it with thekey she stole from Max. She laughs, "The Black Diamondis mineParagraph 2As she holds the diamond in her hands, the lights inhe museum go on. Then an alarm sounds and a team ofThey have caught her! As a police officerhandcuffs Maria, the lead police investigator comes into theroom. Her surprise is so strong that she is unable to speakIt is Max. She yells, How could I have been fooled byyou, a simple police detective? "Max puts his badge backin his pocket and says, "You can think about that in pris-on, and by the way, I speak perfect Italian

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