Question

PART 1

You will want to solve this problem as a Punnett square and use that to answer the questions below. You may select multiple answers for the genotypes, and just one answer for the phenotypic ratio.

Predict the genotypes of the F1 offspring and phenotypic ratios of these offspring that would result from the following fruit fly crosses:

Cross B: a cross between a sepia-eyed male and a white-eyed female (male genotype = X^w+Y se se ; female genotype = X^wX^w se⁺se⁺ )

PART 2

What is the number of each phenotype would you predict in the offspring of F₁xF₁ crosses of B that you described above if you looked at 16 offspring?

Note: You will have to think carefully about what phenotype is going to show in the case of X^wX^wse se and X^wYse se (double homozgyous recessive male or female)

Write only the numbers of predicted offspring in each box, for example: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16. Do not use any words, spaces, or punctuation - just a number. All of your blanks together should add up to 16.

__: WT (Red eyed) males

__: Sepia eyed males

__: White eyed males

__: WT (Red eyed) females

__: Sepia eyed females

__: White eyed females

Answer 1

Cross B: sepia eyed male and white eyed female

Genotypes P1:    Xw+ Y se se                        X                            Xw Xw se+ se+

Gametes:             Xw+ se ; Y se                                                  Xw se+

F1 Cross              

Gametes	Xw se+	Xw se+
Xw+ se	Xw+ Xw se+ se Red eyed female	Xw+ Xw se+ se Red eyed female
Y se	Xw Y se+ se White eyed male	Xw Y se+ se White eyed males

Phenotypic ratio: Red eyed Females: White eyed males (1:1)

F2 cross               Xw+ Xw se+ se                                  X                            Xw Y se+ se

Gametes	Xw+ se+	Xw+ se	Xw se+	Xw se
Xw se+	Xw+ Xw se+ se+ Red female	Xw+ Xw se se+ Red female	Xw Xw se+ se+ White female	Xw Xw se+ se White female
Xw se	Xw+ Xw se+ se Red female	Xw+ Xw se se Sepia female	XwXw se+ se White female	XwXw se se White female
Y se+	Xw+ Y se+ se+ Red male	Xw+ Y se+ se Red male	Xw Y se+ se+ White male	Xw Y se+ se White male
Y se	Xw+ Y se+ se Red male	Xw+ Y se se Sepia Male	Xw Y se+ se White male	Xw Y se se White male

The double recessive homozygous will be white as white mutation prevents formation of any color pigment

Phenotypic ratios                                          

3: WT males

1: Sepia eyed males

4: white eyed males

3: WT red eyed females

1: sepia eyed female

4: white eyed females