Question

Color blindness is a sex-linked recessive trait. A mother with normal color vision and a colorblind father have a colorblind daughter. Which of the following statements is correct?

Answer 1

The most common type of color blindness is a sex-linked trait, meaning the gene is carried on the chromosomes that determine sex. In this case, it's carried on the X chromosome.
There are other types of color blindness that are inhereted that are not sex-linked, so it doesn't matter which parent is the carrier.


Males are XY, and therefore can pass either an X or Y to their offspring, making them the actual determinants of the sex of the offspring. Females are XX, and so can only contribute an X. In the case of color blindness, since males only get one X, if that has the gene for color blindess on it, the male will be color blind (in this case, we'll call that one "x" rather than "X". In the case of females, she has two - so if only ONE of her X has the gene, she will be a carrier, but will not have it (Xx). If her father is colorblind (xY), and her mother is a carrier (Xx), she has a 50% chance of being colorblind (she'll either be "xx" or "Xx). If her mother IS colorblind (xx) and her father is too (xY), then there is only one outcome: "xx".


So, if a color blind mother (xx) has children with a non color blind father (XY), there are the possibilites: xX, xY. Her daughters will be carriers, and her sons will be color blind.


If a color blind mother (xx) has children with a color blind father (xY), then these are the possiblities: xx, xY. All children will be color blind.


To sum up, a mother with sex-linked colorblindness will always have color blind sons, and daughters will have a 50% chance of being color blind, depending on if the father is or not.

Answer 2

Not exactly sure where the "following statements" are but I do know that all that is true.

Answer 3

she is right its true