Practice question

Interaction classifications include complementary 9:7, duplicate dominant 15:1, dominant epistasis 12:3:1, recessive epistasis 9:3:4 and inhibitory 13:3, all requiring two nuclear non-allelic genes influencing same trait via pathway. Loss of entire chromosome represents aneuploidy involving dosage imbalance of hundreds of loci due to nondisjunction, not specific pairwise masking between defined loci. Mitochondrial mutations, genomic imprinting and duplication modulate expression but remain conceptually distinct mechanisms. Chromosome loss fails definition of interaction because phenotype reflects massive gene loss rather than epistatic relationship between two loci.