Final answer:
The number of heterozygous gene pairs in the gamete 'AaBbCC' is 2.
Step-by-step explanation:
A heterozygous gene pair refers to a pair of genes where the two alleles (versions of a gene) are different. In the given gamete 'AaBbCC', there are three genes being considered: gene A, gene B, and gene C.
Each gene has two alleles, represented by the uppercase and lowercase letters. So, to determine the number of heterozygous gene pairs, we count the number of genes where the allele combination is different. In this case, there are two heterozygous gene pairs: Aa and Bb.