Question

If a color blind woman marries a normal visioned man, their sons will be:

• A. all normal visioned
• B. one-half colour blind and one-half normal
• C. three-fourths colour blind and one-fourth normal
• D. all colour blind

Answer 1

Answer: (D)

all colour blind

Answer 2

Color blindness is an X-linked recessive condition, which means it is associated with the X chromosome. In males, the presence of just one copy of the affected gene on their single X chromosome (XcY) is enough to manifest the disorder. Females, with two X chromosomes (XX), will exhibit the condition only if they possess two copies of the affected gene (XcXc). However, if they are heterozygous for this trait (XcX), having one X chromosome with the affected gene and one with the normal allele, they will themselves be free from the condition but can transmit it as carriers. In the context of the question, where the female is color blind (XcXc) and the father has normal vision (XY), all their sons will inherit the condition (XcY) since they receive one X chromosome from their mother, which carries the affected gene, and one Y chromosome from their father.

So, the correct option is (D): all colourblind