Blood Types & genotypes?

1. I forget the notation, but the points needed are that colour-blindness is sex-linked (and recessive) because it's on the X choromosome and O is simply recessive to A.

So the man's only copy of the eye-colour gene is the faulty recessive one, whilst the woman has one faulty version and one good version.

The man must have 2 copies of the 'O' allele to be O type. The woman must have 1 'A' allele and 1 'O' allele to be A type yet able to pass on an 'O' so that her daughter can be O type.

2.a) 50% The child will get an 'O' allele from dad and either an 'A' or a 'B' from mum.

b) The child would do better with dad's blood. O types have neither A nor B antigens on their blood. B types develop anti-A antibodies, and as mum's have both A and B antigens, the child could have a very dangerous reaction to her blood when his/her immune system senses the relevant antigen.

Blood varieties are an occasion of codominance. O is recessive to the two A and B, yet A and B are codominant. So: AO and AA genotypes are A phenotype. BO and BB are B. OO is O. AB is AB.