Colorblindness is a sexed-linked recessive trait, while normal color vision is d
ID: 58794 • Letter: C
Question
Colorblindness is a sexed-linked recessive trait, while normal color vision is dominant.
A. If two parents with normal vision have a colorblind son, what are the parent’s genotypes?
B. What are the chances that their daughter will be colorblind?
a. XBXb x XbY; b. 100%
a. XbXb x XBY; b. 50%
a. XBXB x XbY; b. 25%
a. XBXb x XBY; b. 0%
a. XBXb x XBY; b. 75%
A.a. XBXb x XbY; b. 100%
B.a. XbXb x XBY; b. 50%
C.a. XBXB x XbY; b. 25%
D.a. XBXb x XBY; b. 0%
E.a. XBXb x XBY; b. 75%
Explanation / Answer
A. Since color blindness is an X linked trait, this indicates that if both parents are normal, the father is genotypically wildtype while the mother is a carrier. Hence the correct genotypes would be XBY and XbXB
B. IF they have a daughter the chances that she would be color blind is 0%. Since she will get a normal X from her father, even if she gets the defective allele from her mother, she will only be a carrier but not suffer.
Hence the correct option would be D.