Under what circumstances would a food pyramid be a more useful model than a food chain?

Which of the following matches the organisms described with the correct domain? a. bacteria--unicellular, eukaryotic organisms with cell walls that do not contain peptidoglycanb. archaea--multicellular, eukaryotic organisms that do not have cell wallsc. eukarya--single-celled and multicellular organisms, with a defined nucleus and a variety of nutritional sourcesd. bacteria--unicellular, eukaryotic organisms that always lack cell walls

Moving down the ramp from 6 meters to

There are fewer than 100 naturally occurring elements in the universe, but there are millions of different unified substances. explain how this can be true.