A woman is a carrier of the X-linked recessive color blindness gene. She has children with a man with normal color vision. Which of the following is true of their offspring? a. All the males will be color blind; b. All the females will be carriers; c. Half the females will be color blind; d. Half the males will be color blind.

Verified step by step guidance

1. Understand the genetics involved: Color blindness is an X-linked recessive trait. This means the gene causing color blindness is located on the X chromosome and is recessive.
2. Analyze the mother's genotype: Since the woman is a carrier and not color blind, her genotype must be XcX, where Xc represents the X chromosome carrying the color blindness gene.
3. Analyze the father's genotype: The man has normal color vision and thus his genotype is XY, where Y represents the Y chromosome which does not carry the color blindness gene.
4. Determine the possible genotypes of the offspring: The mother can pass on either Xc or X, and the father can pass on either X or Y. This results in four possible combinations for their children: XcX, XX, XcY, XY.
5. Conclude the probabilities: From the combinations, XcY represents a color blind male (since Y does not mask the recessive Xc), and XY represents a normal male. Thus, half of the male children (XcY and XY) will be color blind, making option 'd' correct.

Key Concepts

X-linked Inheritance

X-linked inheritance refers to the pattern of genetic transmission of traits located on the X chromosome. In this case, color blindness is an X-linked recessive trait, meaning that males (who have one X and one Y chromosome) are more likely to express the trait if they inherit the affected X chromosome, while females (who have two X chromosomes) can be carriers if they have one affected X chromosome.

Carrier Status

A carrier is an individual who possesses one copy of a recessive allele that does not manifest in their phenotype. In this scenario, the woman is a carrier of the color blindness gene, meaning she has one normal X chromosome and one affected X chromosome. This status allows her to pass the affected allele to her offspring without being color blind herself.

Punnett Square

A Punnett square is a diagram used to predict the genetic outcomes of a cross between two individuals. By setting up a Punnett square for this scenario, we can visualize the potential genotypes of the offspring, helping to determine the likelihood of color blindness in males and carrier status in females based on the parents' genotypes.