试题与答案

某植物块根的颜色由两对自由组合的基因共同决定,只要基因R存在,块根必为红色,rrY或

题型:填空题

题目:

某植物块根的颜色由两对自由组合的基因共同决定,只要基因R存在,块根必为红色,rrY或rrYy为黄色,rryy为白色;在基因M存在时果实为复果型,mm为单果型。现要获得白色块根、单果型的三倍体种子。

请写出以二倍体黄色块根、复果型(rrYyMm)植株为原始材料,用杂交育种的方法得到白色块根、单果型三倍体种子的主要步骤。

答案:

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题型:阅读理解

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     John has to get up at 4:30 every morning to delivers his papers. It takes him longer to deliver the papers on Sundays. The papers on Sundays are much bigger than those on weekdays.

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    C. He's a teacher.

    D. He's a postman

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    A. 50

    B. 80

    C. 40

    D. 2

3. About 40 customers take the papers _____.

    A. on Sundays

    B. on weekdays

    C. on weekdays and Sundays

    D. every day

4 John gets up ______ every day.

    A. early

    B. late

    C. at six thirty

    D. at three forty

5. It takes John longer to deliver the papers on Sundays because _____.

    A. he has t o deliver many more papers.

    B. he is always too tired to deliver the papers.

    C. the papers are much bigger

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