【单选题】现有两个非常大的某昆虫种群,个体间随机交配,没有迁入和迁出,无突变,自然选择对 A 和 a 基因控制的性状没有作用。种群 1 的 A 基因频率为 80% , a 基因频率为 20% ;种群 2 的 A 基因频率为 60% , a 基因频率为 40%. 假设这两个种群大小相等,地理隔离不再存在,两个种群完全合并为一个可随机交配的种群,则下一代中 Aa 的基因型频率是 A . 75% B ....
【单选题】In Amsterdam, the capital of Holland, there is a unique Children Restaurant. It is run wholly by the children. From the manager to the cooks, cashiers, waiters or waitresses and other staff members ar...
A.
can earn only four dollars a day
B.
are fond of working there
C.
will have to work there for over a month
D.
do not need to be trained before they work in the restaurant
【简答题】In Amsterdam, the capital of Holland, there is a unique Children Restaurant. It is run wholly by the children. From the manager to the cooks, cashiers, waiters or waitresses and other staff members ar...