Final answer:
Hox genes are homologous genes found in bilaterian animals that control the anterior to posterior patterning of the body plan.
Step-by-step explanation:
Hox genes are homologous genes found in bilaterian animals that are responsible for the anterior to posterior patterning of the body plan. They control the development of various body segments, the number and placement of appendages, and head-tail directionality. Hox genes serve as master control genes and can turn on or off other genes by encoding transcription factors. They are highly conserved across the animal kingdom and their positions on chromosomes reflect the anterior-posterior axis of the animal's body.