Final answer:
In an epistatic interaction between genes, one gene is suppressive/epistatic while the other is hypostatic/masked.
Step-by-step explanation:
In an epistatic interaction between two separate genes, one is suppressive/epistatic while the other is hypostatic/masked.
Epistasis refers to an antagonistic interaction between genes, where one gene interferes or masks the expression of another. The gene that does the suppressing or interfering is called epistatic, while the gene that is suppressed or masked is called hypostatic.
For example, in the shepherd's purse plant, the genes A and B control seed shape. When both genes are homozygous recessive (aabb), the seeds are ovoid. If either of the dominant alleles for these genes is present, the result is triangular seeds. Here, the dominant allele for A and B are epistatic, while the recessive allele is hypostatic.