An easy way to calculate the amount of energy available at each level is to what?

Starting at the smallest, most simple level and working your way up to the most complex, explain how the following terms are connected. note-these terms are not in order molecules, atoms, organism, tissues, cells, organ systems, organs

Draw the structure of dna nucleotide with adenine as nitrogenous base

How can antibodies "remember" a particular bacterial invader or "antigen" on that invader?