Why does the the amount of oxygen in the atmosphere stay almost the same for long periods of time?​

oxygen, (as well as carbon dioxide) remain nearly constant in the atmosphere by the process of photosynthesis (in plants). carbon dioxide remains relatively consistent because of respiration (in animals ect).

the match lol

the sugar-phosphate backbone forms the structural framework of nucleic acids, including dna and rna. this backbone is composed of alternating sugar and phosphate groups, and defines directionality of the molecule.