6. aa and cc ; two lower-case letters indicate the expression of a recessive trait because there is no dominant trait to mask it. (Dominant alleles are capitalized).
7. 1 pp (lower case = recessive)
7.2 Pp, PP; because the white flower is pp, the flower's recessive trait is white. White will only be expressed in the absence of a P, the dominant gene. If a P is in the genotype, it will mask the p allele' causing the flower to be purple.