MENDEL'S LAWS OF INHERITANCE 



285 



Parents 



Yellow 



Round 



GG WW 



—MB 



Fig. 18.2. The dihybrid cross between yellow-round and green-wrinkled peas. Yellow is 

 dominant to green, and round is dominant to wrinkled. The Fz ratio shows that the segrega- 

 tion of the genes for yellow and green must have been independent of the segregation of the 

 genes for round and wrinkled. 



