Final answer:
Woese added comparative gene sequencing, including homologous DNA and RNA sequences, to the morphological data in order to create his new classification system.
Step-by-step explanation:
Woese constructed his new classification system by adding comparative gene sequencing to the morphological data.
He used homologous DNA and RNA sequences to reveal the extensive variability of prokaryotes and justify the separation of prokaryotes into two domains: bacteria and archaea. Comparing physical features alone is insufficient to differentiate between prokaryotes with tremendous biochemical diversity and genetic variability.