The permanent gases whose percentages do not change from day to day are nitrogen<span>, </span>oxygen<span> and</span>argon<span>. </span>Nitrogen<span> accounts for 78% of the atmosphere,</span>oxygen<span> 21% and </span>argon<span> 0.9%. Gases like </span>carbon dioxide<span>, nitrous oxides, </span><span>methane</span>
Thymine and cytosine are classified as "Pyrimidines" and have one ring of carbon and nitrogen atoms for each base.
A DNA evidence provides the strongest support for the current Eubacteria phylogeny.
