Question

Alleles of the gene that determines seed coat patterns in lentils can be organized in dominance series: marbled > spotted = dotted (codominant alleles) > clear A lentil plant homozygous for the marbled seed coat pattern allele was crossed to one homozygous farther spotted *tern allele. In another cross, homozygous dotted lentil plant was crossed to one homozygous for clear. An Fl plant from the first cross was then mated to an Fl plant from the second cross. a.What phenotypes in whet proportions are expected from this mating between the two F1types? b. What ere the expected phenotypes of the Fl plants from the two original parental crosses?

Answer 1

Answer:

a.The phenotypic proportions obtained after having the genotypes are 50% marbled seeds, 25% spotted and dotted seeds since they are codominant, 25% spotted seeds.

b. Taking into account the F1 genotypes in the previous point, the expected phenotypes for the first crossing are 100% marbled seeds and for the second crossing 100% dotted seeds.

Explanation:

Let's suppose:

Marbled allele: M

Spotted allele: S

Dotted allele: D

Allele for Clear: C

a. Because both crosses were between homozygous parents, the entire F1 genotype is the same.

For the first crossing the descendants have the MS genotype, and for the second crossing the descendants have the DC genotype. It is enough to make a Punnett square to obtain the different combinations of genotypes between the crossing of MS and DC.