Q. In a family father had a trait but mother did not. All their sons and daughter had this trait. The same trait was found in some grand daughters, through daughter were married to the normal persons. Choose the correct pedigree chart for the condition
A) [image:5_image17.png]
B) [image:5_image18.png]
C) [image:5_image19.png]
D) [image:5_image20.png]
Explanation
Criss-cross Inheritance It is a type of sex-linked inheritance, where a parent passes the traits to the grand child of the same sex through offspring of the opposite sex, that is, father passes the traits to grandson through his daughter (diagynic), while the mother transfers traits to her grand daughter through her son (dia-andric). It was first studied by Morgan (1910) in case of eye colour in Drosophila. Criss-cross inheritance is applicable to most sex-linked disorders in humans, e.g., red green colour blindness, haemophilia
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.