Answer
a) 1 (100%)
b) 1/32
c) 1/8
d) 1/2
Work Step by Step
As with many other seemingly complex problems in this chapter, use the laws of probability combined with the fact that for any gene, common crosses work as follows: ZZ x zz gives all Zz; Zz x Zz gives 1/4 ZZ: 1/2 Zz: 1/4 zz. So, for example, in d), the A and C gene crosses are of the type that only yields heterozygotes (100%), so the overall probability is 1x1x1/2, the last number being the probability of a heterozygote from a Zz x Zz type of cross.