When a heterozygous plant with round seeds is mated to a plant with wrinkled seeds what fraction of the progeny are homozygous? 2/3 or 1/4 or 3/4 or 1/2 Solution 1/2 of the progeny will be homozygous because in heterozygous condition the genotype will be Rr and wrinkled seed will have rr genotype because it is expressed only in recessive condition.so when a cross is made between both then half of the progeny will be homozygous recessive (rr) and half will be heterozygous (Rr)..