A diploid plant species has a chromosome number of 2n=4. A particular plant is heterozygous for three genes: gene A (alleles A and a), gene B (alleles B and b), and gene C (alleles C and c). Genes A and B are located on the same chromosome (chromosome 1) and are linked, with the plant's genotype on chromosome 1 being AB/ab. Gene C is on a different chromosome (chromosome 2), and the plant is heterozygous Cc. During meiosis, crossing over occurs between the A and B loci on chromosome 1.
Explain how crossing over and random orientation of homologous chromosomes contribute to the genetic variation of the gametes produced by this plant. In your answer, compare the number of genetically different gamete genotypes that can be produced if crossing over does NOT occur on chromosome 1 with the number if crossing over does occur.