$1.$ Pedigrees

a$.$ If this pedigree shows a recessive disorder caused by homozygosity of the a allele, what are the genotypes of the parents in this pedigree?

I$-1($use letters$)$:

I$-2($use letters$)$:

b$.$ Circle the individuals in the second generation who MUST be heterozygous.

c$.$ If this pedigree shows a dominant disorder caused by the dominant A allele, what are the genotypes of the parents in this pedigree?

I$-1($use letters$)$:

I$-2($use letters$)$:

d$.$ Circle the individuals in the second generation who MUST be heterozygous.

e$.$ What type of mutation could have caused this dominant disease? Why do you think so$?$