小麦的粒色受不连锁的两对基因R1和r1、R2和r2控制。R1和R2决定红色,

小麦的粒色受不连锁的两对基因R1和r1、R2和r2控制。R1和R2决定红色,r1和r2决定白色,R对r不完全显性,并有累加效应,所以麦粒的颜色随R的增加而逐渐加深。将红粒(R1R1R2R2)与白粒(r1r1r2r2)杂交得F1,F1自交得F2,则F2的表现型有

A.4种  B.5种  C.9种  D.10种

 

答案

B

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