题目内容：

英语翻译
in sweet peas,the synthesis of purple anthocyanin pig-ment in the petals is controlled by two genes,B ans D .the pathway is
white-------(geneB enzyme)------blue------(gene D enzyme)----anthocyanin(purple)
a.what color perals would you expect in a pure-breeding plant unable to catalyze the first reaction?
b.what color perals would you expect in a pure-breeding plant unable to catalyze the second reaction?
c.if the plants in parts a and b are crossed,what color perals will the F1 plants have?
d.what ratio of purple:blue:white plants would you expect in the F2