题干

已知黑斑蛇与黄斑蛇杂交,子一代既有黑斑蛇,又有黄斑蛇;若再将F1黑斑蛇之间交配F2中有黑斑蛇和黄斑蛇.下列结论中正确的是(    )

A:所有黑斑蛇的亲代中至少有一方是黑斑蛇

B:蛇的黄斑为显性性状

C:F1黑斑蛇的基因型与亲代黑斑蛇的不同

D:F2中黑斑蛇的基因型与F1黑斑蛇的基因型相同

上一题 下一题 0.0难度 选择题 更新时间:2019-05-06 08:45:24

答案(点此获取答案解析)

A

同类题5

完形填空

    Years ago, I lost my sight completely. I would do anything for a 1 . In fact, desperate and 2 , I tried every supplement, experimental trial, diet and anything anyone 3 . All for nothing.

    But now, after 25 years in physical darkness, my life is 4 than ever. The change began one day, many years ago, when I drank my tea 5 , swallowing gulps(一大口) of “poor me” and wondering what my future would 6 . Then, the doorbell rang. Janet came in and brought an idea. “Have you ever thought about working as a(n) 7 ? ” she said, “You speak Spanish. Go for it.”

    Her idea 8 me to make a phone call. And the interpreting company I contacted invited me to take a test. Thank goodness it was 9 .

    “We're so 10 with the results,” the receptionist said the next day, “that we want to send you on your first 11 tomorrow. It's in the Immigration and Naturalization Court.”

    That was the beginning. That was when I began to 12 possibilities when my blindness wouldn't get 13 . The view of my world had changed. Blindness didn't have to label me as

    14 . On the contrary, the blindness improved my ability to 15 information and present a quicker and more 16 interpretation.

    The letters from judges, praising me for my work, 17 me for the hours I'd spent studying, memorizing, and 18 .

    Blindness? Not a barrier any more. 19 , it became a handy 20 to sharpen my creativity. Not only in the courtroom, but at home, in my relationships and in the way I viewed myself.