Question

Red-green color blindness is caused by an X-linked recessive gene. In a family, the mother is a carrier of this gene while the father does not have the gene. What are the possible effects on their children? Select one of the options below as your answer:
A. Half of the daughters are normal and half of the daughters are color-blind.
B. Half of the boys are normal and half of the boys are color-blind.
C. Half of the boys are color-blind and half of the girls are color-blind.

Answer 1

The correct answer is option B, Half of the boys are normal and half of the boys are color-blind

When a  mother carries certain X – linked recessive traits, she passes on this X-linked traits to her son and he will inherit the color vision issue have trouble distinguishing reds and greens While a daughter can be just as carrier of the trait of colorblindness and will have this form of colorblindness only when both her father and mother pass along the X-linked gene. Thus, more men than women are color blind.  

The cross for the above situation is shown below –  

XXr  x XY

XXr – Color deficiency carrier mother

XY – Father without any color deficiency

Off springs produced will be  

XX – unaffected daughter

XXr – Carrier daughter

XY – Unaffected son

XrY – Affected son

Answer 2

B. half of the boys are normal and half of the boys are color-blind. ( boys are most likely to get color blond than girls, the girls can also be carrier like the mother)