There are three domains of life - Archaea, Bacteria, and
Eukarya. All organisms that belong to the domains Archaea or
Bacteria have cell walls. In the domain Eukarya, there are some groups
that have cell walls and others that do not.
Chordata is phylum of the kingdom Animalia which belongs to the domain Eukarya. So, Chordata cannot be a domain.
B12 (cobalamin): Perhaps the most well-known of all the B vitamins, B12 is vital for neurological function, DNA production and red blood cell development. B12 is found naturally in animal sources like meats, eggs, seafood and dairy.
