Structure of a ribosome

Ribosomes are macromolecular machines, found within all living cells, that perform biological protein synthesis. Ribosomes link amino acids together in the order specified by the codons of messenger RNA molecules to form polypeptide chains.

Explanation:

Plants breathe in the carbon dioxide that humans and animals let out of their body when they breathe out, and when plants breathe the CO2 in, the let out oxygen which humans and animals breathe in and it keeps going in a cycle. Because of the cycle the oxygen and CO2 in the atmosphere stays stable