6. The respiratory system is responsible for gas exchange in the body. It takes oxygen into the body and releases carbon dioxide. Which of the following identifies the
structural hierarchy of organization that makes up the respiratory system in order of
increasing complexity?

when atoms of different types of elements join together, they make molecules called compounds. water consists of compound molecules made up of 2 hydrogen atoms and 1 oxygen atom. this is why it's called h2o. water will always have 2 times the number of hydrogen atoms as oxygen atoms.

lesson summarykaryotypes a genome is the full set of all the genetic information that an organism carries in its dna. chromosomes arebundles of dna and protein found in the nucleus of a eukaryotic cell.