Question

In Drosophila melanogaster, round eyes (rai+) are dominant to raisin eyes (rai). Round eyes are found in wild-type flies, while raisin eyes are the result of a mutant allele. If a heterozygous parent is crossed with a homozygous recessive parent, then what are the correct genotypic ratios for the F1 progeny?

A. 4:0, round eyes
B. 3:1, raisin eyes:round eyes
C. 1:1, round eyes:raisin eyes
D. 4:0, raisin eyes

Answer 1

Answer:

The correct genotypic ratios for the F1 progeny is 1 round eyes : 1 raisin eyes (Option c)

Explanation:

Available data:

• round eyes (rai+) are dominant to raisin eyes (rai)

• round eyes are found in wild-type flies,

• raisin eyes are the result of a mutant allele

Cross: A heterozygous parent (rai+ rai) is crossed with a homozygous recessive parent (rai rai)

Parental)  rai+ rai     x     rai rai

Gametes) rai+   rai       rai    rai

Punnet square)   rai+        rai

                rai     rai+ rai    rai rai

                rai     rai+ rai    rai rai

F1) Progeny genotype: 2/4= 1/2 rai+ rai, round-eyed individuals

                                      2/4=1/2 rai rai, raisin-eyed individuals

The correct genotypic ratios for the F1 progeny is 1 round eyes : 1 raisin eyes