Question

Blue eye colour in human is recessive to brown eye colour. The expected children of a marriage between a blue eyed woman and a brown eyed man who had a blue eyed mother will be

• A. All black eyed
• B. All blue eyed
• C. All brown eyed
• D. One blue eyed and one brown eyed

Answer 1

The correct option is D One blue eyed and one brown eyed

Blue eye colour (b) in human is recessive to brown eye colour (B), thus "b" will express itself in homozygous condition only (bb). The dominant "B" allele can express itself in both homozygous and heterozygous conditions. The man had a blue eyed mother (bb); thus phenotype of the man is "Bb" as he has received one "b" allele from the blue eyed mother. The expected children of a marriage between the blue eyed woman (bb) and a brown eyed man (Bb):
Parent generation : Bb (man) X bb (woman)

Gametes : Bb ----> bb	B	b
b	Bb (Brown)	bb (Blue)
b	Bb (Brown)	bb (Blue)

Children = 1 Blue : 1 Brown. Correct option is D.