Answer:
9:3:3:1
Explanation:
If alleles of two genes separate randomly during anaphase-I of meiosis, some new combinations of the alleles are formed in the gametes. A heterozygous genotype for two loci (let's support TtRr) produces a total of four types of gametes in 1:1:1:1 ratio (TR, Tr, tR, and tr). The random fusion of these gametes from two double heterozygous parents (TtRr x TtRr) gives a phenotype ratio of 9:3:3:1. Here, 9/16 F2 progeny exhibit dominant phenotype for both loci while 1/16 exhibits recessive phenotype for both the genes. Rest 3/16 and 3/16 F2 progeny express dominant trait for one gene and recessive for the other.
