Human Heredity 11th Edition by Michael Cummings

Exercise 23

The following hypothetical pathway in which substance A is converted to substance C by enzymes 1 and 2. Substance B is the intermediate produced in this pathway:
An individual is heterozygous for a recessive mutation in enzyme 1 and heterozygous for a recessive mutation in enzyme 2. This individual marries an individual with the same genotype. List the possible genotypes of their children. For every genotype, determine the activity of enzymes 1 and 2, assuming that the mutant alleles have 0% activity and that each normal allele has 50% activity. For every genotype, determine if compound C will be made. If compound C is not made, list the compound that will be in excess.