题干

桦尺蛾的黑色(A)对浅色(a)是显性.1870年,某一区域的桦尺蛾以浅色为主,浅色占70%,杂合子占所有个体的20%.由于工业污染,该区域的桦尺蛾毎年浅色个体减少10%,黑色个体增加10%.30年后该区域的桦尺娥个体以黑色为主,几乎看不到浅色个体,以下叙述不正确的是(  )

A:该区域的桦尺蛾个体间存在体色的差异,体现的是遗传多样性

B:30年期间桦尺蛾种群形成了新物种

C:1871年该区域的桦尺蛾群体中,隐性基因(a)的基因频率为77%

D:种群基因频率的改变是通过环境对生物个体的选择实现的

上一题 下一题 0.0难度 选择题 更新时间:2018-04-06 09:59:05

答案(点此获取答案解析)

B

同类题3

阅读下列短文,从每题所给的四个选项中,选出最佳选项。

    Everyone gathered around and Paddy read out loud, slowly, his tone growing sadder and sadder. The little headline said: BOXER RECEIVES LIFE SENTENCE.

Frank Cleary, aged 26, professional boxer, was today found guilty of the murder of Albert Cumming, aged 32, laborer, last July. The jury (陪审团) reached its decision after only ten minutes, recommending the most severe punishment the court could give out. It was, said the judge, a simple case. Cumming and Cleary had quarreled violently at the Harbour Hotel on July 23rd and the police saw Cleary kicking at the head of the unconscious Cumming. When arrested Cleary was drunk but clear-thinking…

    Cleary was sentenced to life imprisonment with hard labour. Asked if he had anything to say, Cleary answered, “Just don't tell my mother.”

     “It happened over three years ago,” Paddy said helplessly. No one answered him or moved, for no one knew what to do. “Just don't tell my mother,” said Fee numbly. “And no one did! Oh, God! My poor, poor Frank!” Paddy wiped the tears from his face and said. “Fee dear, pack your things. We'll go to see him.”

    She half-rose before sinking back, her eyes in her small white face stared as if dead. “I can't go,” she said without a hint of pain, yet making everyone feel that the pain was there. “It would kill him to see me. I know him so well— his pride, his ambition. Let him bear the shame alone, it's what he wants. We’ve got to help him keep his secret. What good will it do him to see us? ”

    Paddy was still weeping, but not for Frank, for the life which had gone from Fee’s face, for the dying in her eyes. Frank had always brought bitterness and misfortune, always stood between Fee and himself. He was the cause of her withdrawal from his heart and the hearts of his children.

    Every time it looked as if there might be happiness for Fee, Frank took it away. But Paddy's love for her was as deep and impossible to wipe out as hers was for Frank.

    So he said, “Well, Fee, we won't go. But we must make sure he is taken care of. How about if I write to Father Jones and ask him to look out for Frank?”

    The eyes didn't liven, but a faint pink stole into her cheeks. “Yes, Paddy, do that. Only make sure he knows not to tell Frank we found out. Perhaps it would ease Frank to think for certain that we don't know.”