問題詳情
14. John and Mary are planning to start a family. John was married once before, and he and his first wife had a child with cysticfibrosis. The brother of his current wife, Mary, died of cystic fibrosis. What is the probability that John and Mary will have ababy with cystic fibrosis? (Neither John, Mary, nor their parents have cystic fibrosis.)
(A)1/4
(B)1/6
(C)1/8
(D) 1/12
(E)1/16
參考答案
答案：B
難度：非常困難0.125
統計：A(19),B(5),C(4),D(0),E(2)
用户評論
【生物生理生化-認同按讚】評論
cystic fibrosis是體隱(aa才發病)由體目敘述可知John的基因是Aa,為帶原者Mary的父母是Aa配Aa所以Mary有1/3的機率是AA,2/3的機率是Aa(不會是aa)John和Mary小孩是aa的機率:1(John是Aa的機率)x2/3(Mary是Aa的機率)x1/4(AaXAa,小孩是aa的機率)=1/6