A color-blind woman marries a man who is not color-blind. All of their sons are color-blind, but none of their daughters are color-blind. Color-blindness is likely...?
Answer choices:
1.the result of having too few chromosomes.
2.the result of having an extra chromosome.
3.a sex-linked trait.
4.a recessive trait.
MY ANSWER:3.a sex-linked trait.
Right.
Thanks!
You're welcome.
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what is the awnser??
Your answer is correct. Color-blindness is indeed a sex-linked trait. To understand why, let's first understand the biology behind it.
Color-blindness is caused by a mutation in the genes that are responsible for the perception of colors, usually the red and green color receptors. These genes are located on the X chromosome. Since women have two X chromosomes, if one of them contains the mutation, the other X chromosome usually compensates for it, resulting in normal color vision. However, men only have one X chromosome, which means they have a higher chance of inheriting color-blindness if the X chromosome they receive from their mother contains the mutation.
In this case, if a color-blind woman (who has one affected X chromosome) marries a man who is not color-blind (who does not have the mutation on his X chromosome), all of their sons will receive the affected X chromosome from their mother and the Y chromosome from their father. Since the Y chromosome does not have the gene for color vision, the sons will be born color-blind. On the other hand, none of their daughters will be color-blind because they receive one normal X chromosome from their mother (the one without the mutation) and one X chromosome from their father, which also does not have the mutation.
Therefore, based on this pattern of inheritance, we can conclude that color-blindness is a sex-linked trait.