In the absence of a particular human enzyme, the sugar galactose is not metabolized and instead accumulates in the body, adversely affecting the development of the nervous system in infant children. This disorder, known as galactosemia, is due to the expression of an allele, g, which is recessive to the allele for normal enzyme production g+. Through an analysis of their family's genetic history, both phenotypically normal members of a couple are identified as heterozygous for the alleles governing this trait. What is the probability that:

a) their first child will be galactosemic?

b) their third child will be normal for galactosemic utilzation?

c) in a family of five, the first child will be galactosemic and the last four normal?

d) in a family of five, there would be four normal males and one galactosemic female?