Answer:
SsBB x SsBB
or
SsBB x SsBb
Explanation:
SS- short hair
ss - long hair
BB- black hair
bb- white hair
Total the number of offspring produced = 2518+817=3335
Where 2518= short haired, black offspring SSBB or SsBb
817= Longed Hair, black offspring ssBB or ssBb
To get the offspring proportion for short hair black offspring
2518/3335×100 = 75.5%
long-haired, blackoffspring =817/3335×100 = 25%
This gives ratio of 3:1 as against the proposed dihybrid phenotypic ratio of Mendel experiment 9:3:3:1
Now, if you remember a dihybrid cross results in 9:3:3:1 phentoype ratio. That is when both parents are heterozygous for both alleles. So we can rule that out since it doesn't match our 3:1 ratio.
Since all the offspring are black , it means one parent is homozygous dominant for black and the other parent is either homozygous or heterozygous for the black allele.
Since the ratio is 3:1, for the hair length
That leaves us with the short hair. Since the ratio is 3:1, both parents are heterozygous for hair length.
Therefore, the possible parental genotype is
SsBB x SsBB
or
SsBB x SsBb
