What is the chief characterristic of vertebrates?

The term facultative anaerobe refers to an organism that

Which organelle plays a role in intracellular digestion?

American scientist, linus pauling, was one of many scientists racing to discover the molecular structure of dna. pauling initially thought that the molecule was a triple helix. later, james watson and francis crick unveiled their double helix model, which turned out to be an accurate description of the molecule's shape. why did watson and crick succeed when pauling failed?