题干

如图所示为患甲、乙、丙、丁四种单基因遗传病的家系图.已知甲病为伴性遗传病,Ⅱ﹣9不携带丙病的

致病基因,控制丙病的基因与控制乙病的基因位于两对同源染色体上,丁病在自然人群中男女患病概率

相同.下列相关叙述正确的是  (  )

A:在自然人群中,甲病男性患者多于女性患者

B:丙病可能是红绿色盲,母亲患丙病,儿子也应患丙病

C:乙病应为常染色体隐性遗传病,控制乙病的基因与控制丁病的基因独立遗传

D:丁病很可能是常染色体隐性遗传病,因该家族丁病的发病率较高

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答案(点此获取答案解析)

B

同类题3

Read the passage and fill in the blanks with the proper words(在短文的空格内填入适当的词,使其内容通顺,每空格限填一词,首字母已给)
    A thousand years ago, Hong Kong was covered by a thick forest. As more and more people came to live in Hong Kong, these trees were cut down and burnt. Now there is no forest left, though there are still some small areas covered with trees. We call these “woods”.
    Elephants, tigers and many o____  animals were living in the thick forest. When people came to live in Hong Kong, the animals began to die out. Early farmers grew rice and r____  pigs and chickens in the valleys. They cut down the trees and burnt them. They needed fire to keep t____  warm in winter, to cook their food and to drive away the dangerous animals. Elephants quickly d____  because there was not enough food for them. So did most of the wolves and tigers.
    You might think that there are no longer any animals in Hong Kong e____  in the zoos, but there are still about 36 different animals living there. One of the most lovely of Hong Kong's animals is the barking deer. There are beautiful little animals w____  a rich brown coat and a white patch under the tail. They look like deer but they are much smaller. They are less than two feet high. They make a noise rather like a dog barking. In Hong Kong the barking deer has only one r____  enemy- men. People hunt these little animals though it is illegal(犯法的). There are now not many barking deer left. So it is important for people to protect these wild animals.