Question

1. cross a homozygous red eyed female with a white eyed male. write the genotypes and phenotypes.
2. cross a heterozygous red eyed female with a red eyed male. write the genotypes and phenotypes.

Explanation:

(Question 4):

Step1: Define allele notation

Let $X^R$ = red eye allele (dominant), $X^r$ = white eye allele (recessive); males are $X^Y$, females are $X^X$.

Step2: Parental genotypes

Homozygous red-eyed female: $X^RX^R$; white-eyed male: $X^rY$

Step3: Set up Punnett square

$$\begin{array}{c|cc} & X^R & X^R \\ \hline X^r & X^RX^r & X^RX^r \\ Y & X^RY & X^RY \\ \end{array}$$

Step4: Identify offspring genotypes/phenotypes

All female offspring: $X^RX^r$; all male offspring: $X^RY$. All have red eyes.

(Question 5):

Step1: Parental genotypes

Heterozygous red-eyed female: $X^RX^r$; red-eyed male: $X^RY$

Step2: Set up Punnett square

$$\begin{array}{c|cc} & X^R & X^r \\ \hline X^R & X^RX^R & X^RX^r \\ Y & X^RY & X^rY \\ \end{array}$$

Step3: Identify offspring genotypes/phenotypes

Genotypes: $X^RX^R$, $X^RX^r$, $X^RY$, $X^rY$. Phenotypes: Red-eyed females ($X^RX^R$, $X^RX^r$), red-eyed male ($X^RY$), white-eyed male ($X^rY$).

Answer:

Question 4:

• Parental Genotypes: Female = $X^RX^R$, Male = $X^rY$
• Offspring Genotypes: All females $X^RX^r$, All males $X^RY$
• Offspring Phenotypes: 100% red-eyed (all females and males)

Question 5:

• Parental Genotypes: Female = $X^RX^r$, Male = $X^RY$
• Offspring Genotypes: $X^RX^R$, $X^RX^r$, $X^RY$, $X^rY$
• Offspring Phenotypes: 50% red-eyed females, 25% red-eyed males, 25% white-eyed males (75% red-eyed, 25% white-eyed total)