Question

question 7 of 10
color - deficient vision is a sex - linked recessive trait in humans. parents with
the following genotypes have a child:
$x^{r}x^{r}×x^{r}y$
what is the probability that the child will have color - deficient vision?
a. 1.00
b. 0.00
c. 0.50
d. 0.25

Explanation:

Step1: Analyze the gametes

The female \(X^{R}X^{r}\) can produce two types of gametes: \(X^{R}\) and \(X^{r}\). The male \(X^{r}Y\) can produce two types of gametes: \(X^{r}\) and \(Y\).

Step2: Create a Punnett square

	\(X^{R}\)	\(X^{r}\)
\(Y\)	\(X^{R}Y\) (normal male)	\(X^{r}Y\) (color - deficient male)

Step3: Calculate the probability

There are 4 possible genotypes for the offspring. The color - deficient genotypes are \(X^{r}X^{r}\) and \(X^{r}Y\). So the number of color - deficient offspring is 2 out of 4. The probability \(P=\frac{2}{4}= 0.5\)

Answer:

C. 0.50