Question

cross a carrier female with a colorblind male. what is the phenotype ratio of the offspring?
○ 1 normal vision daughter: 1 colorblind daughter: 1 normal vision son: 1 colorblind son
○ 2 normal vision daughters: 2 normal vision sons
○ 2 normal vision daughters: 1 normal vision son: 1 colorblind son
○ 1 normal vision daughter: 1 colorblind daughter: 2 normal vision sons

Explanation:

Step1: Define genotypes

Carrier female: $X^CX^c$; Colorblind male: $X^cY$

Step2: Set up Punnett square

$$\begin{array}{c|cc} & X^C & X^c \\ \hline X^c & X^CX^c & X^cX^c \\ Y & X^CY & X^cY \\ \end{array}$$

Step3: Assign phenotypes

• $X^CX^c$: Normal vision daughter
• $X^cX^c$: Colorblind daughter
• $X^CY$: Normal vision son
• $X^cY$: Colorblind son

Step4: Count phenotype ratio

1 normal daughter : 1 colorblind daughter : 1 normal son : 1 colorblind son

Answer:

1 Normal Vision Daughter: 1 Colorblind Daughter: 1 Normal Vision Son: 1 Colorblind Son