Question

Croaking in frogs is controlled by one gene with a pair of alleles - dominant uttering (R) and recessive muttering (r). Eye color is inherited by epistatic interaction of two genes with the following possible phenotypes: A_B_ - blue eyes; A_bb - purple eyes and aaB_ or aabb - green eyes. The frog geneticist mated two purple utteres with the following results: Part A 9/16 purple, utterers 3/16 purple, mutterers 3/16 green. utterers 1/16 green. mutterers What were the genotypes of the parents? a. AabbRr x AaBbRr b. AabbRr x AAbbRr c. AabbRr x AabbRr d. AAbbRr x AaBbRr e. AabbRr x Aabbrr f. AaBbrr x AabbRr

Answer 1

The cross with the correct genotypes of the parents is AabbRr x AabbRr -option C-.

Step-by-step explanation:

Available data:

• Dominant uttering (R) and recessive muttering (r)

• Eye color is inherited by epistatic interaction

• A_B_: blue eyes; A_bb: purple eyes; aaB_ or aabb: green eyes.

Cross) AabbRr x AabbRr

Gametes) RAb Rab rAb rab

RAb Rab rAb rab

Punnet Square) RAb Rab rAb rab

RAb RRAAbb RRAabb RrAAbb RrAabb

Rab RRAabb RRaabb RrAabb Rraabb

rAb RrAAbb RrAabb rrAAbb rrAabb

rab RrAabb Rraabb rrAabb rraabb

Note) Each parent has two copies of each gamete, which means that these results should be muliplied by four. But in oder to make it understandable, I resumed it, and just put half of the gametes.

Progeny phenotypes) 9/16 purple, utterers R-A-bb

3/16 purple, mutterers rrA-bb

3/16 green, utterers R-aabb

1/16 green, mutterers rraabb

Option a. AabbRr x AaBbRr: Incorrect, as one of the parents has a genotype for blue eyes, A-B-

Option b. AabbRr x AAbbRr: Incorrect, as one of the parents is homozygote for A, so there would not be any green descendant.

Option c. AabbRr x AabbRr: Correct

Option d. AAbbRr x AaBbRr: Incorrect, as one of the parents has a genotype for blue eyes, A-B-

Option e. AabbRr x Aabbrr: Incorrect, as one of the parents is muttering, rr

Option f. AaBbrr x AabbRr: Incorrect, as one of the parents is muttering, rr and has a genotype for blue eyes, A-B-