What phenotypic ratio would you expect as a result of a test cross between a dihybrid organism and one that is homozygous recessive for alleles at two independent loci?

¼ or 25% will be dihybrid organisms, ¼ will be heterozygous at first locus and recessive homozygous at other locus , ¼ of them will be recessive homozygous at first locus and heterozygous at other locus, and ¼ of them will be homozygous recessive for alleles at two independent loci.

Explanation:

A dihybrid organism is one that is heterozygous at two different genetic loci. So if we name one gene with D and other gene with R, dihybrid organism will have genotype DdRr.

If we cross that organism with the one that is homozygous recessive for alleles at two independent loci ddrr:

P: DdRr  x ddrr