Q. A couple whose sons are colourblind with AB blood group, identify the parents from the following.
A) Mother colourblind with A blood group, and father normal with blood group-B
B) Mother normal with blood group-A, and father colourblind with blood group-B
C) Mother colourblind with blood group-B, and father normal with blood group-B
D) Mother normal with blood group-A, and father colourblind with blood group-B
Explanation
Colour blindness is caused by recessive sex-linked gene carried by X-chromosome. So, in male, one recessive gene is sufficient for its expression, i.e., ൫X େY൯ but female needs two recessive gene൫X େXେ ൯ for the expression of colour blindness. Mother will colourblind with A blood group and father normal with blood group-B as− So, all the sons will be colourblind with AB blood group.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.