Chapter 4, Problem 23P

Three strains of green-seeded lentil plants appear to have the same phenotype. The strains are designated ${\text{G}}_{\text{1}}$, ${\text{G}}_{\text{2}}$, and ${\text{G}}_{\text{3}}$. Each green-seeded strain is crossed to a pure-breeding yellow-seeded strain designated Y. The ${\text{F}}_{\text{1}}$ of each cross are yellow; however, self-fertilization of ${\text{F}}_{\text{1}}$ plants produces ${\text{F}}_{\text{2}}$ with different proportions of yellow- and green-seeded plants as shown below.

For what number of genes are variable alleles segregating in the ${\text{G}}_{\text{1}}$ * Y cross? The ${\text{G}}_{\text{2}}$ * Y cross? In the ${\text{G}}_{\text{3}}$ * Y cross? Explain your rationale for each answer.

b. Using the allele symbols A and a, B and b, and D and d to represent alleles at segregating genes, give the genotypes of parental and ${\text{F}}_{\text{1}}$ plants in each cross.

c. For each set of ${\text{F}}_{\text{2}}$ progeny, provide a genetic explanation for the yellow: green ratio. What are the genotypes of yellow and green ${\text{F}}_{\text{2}}$ lentil plants in the ${\text{G}}_{\text{2}}$* Y cross?

d. If green-seeded strains ${\text{G}}_{\text{1}}$ and ${\text{G}}_{\text{3}}$ are crossed, what are the phenotype and the genotype of F1 progeny?

e. What proportion of the ${\text{F}}_{\text{2}}$ are expected to be green? Show your work.

f. If strains ${\text{G}}_{\text{2}}$ and ${\text{G}}_{\text{3}}$ are crossed, what will be the phenotype of the ${\text{F}}_{\text{1}}$?

g. What proportion of the ${\text{F}}_{\text{2}}$ will have yellow seeds? Show your work