In swamps and bogs with very low dissolved oxygen in water, soils are low in inorganic nutrients required for plant growth because decomposition rates are very low. Microbes have evolved ways to use the available resources found in low oxygen environments. Given this, how should we classify a bacterium that makes ATP by breaking bonds in methane (CH4) and uses carbon in CO2 to make sugars?

i am going to guess that it is co2.

the oxygenated blood then leaves the lungs through pulmonary veins, which return it to the left heart, completing the pulmonary cycle. this blood then enters the left atrium, which pumps it through the mitral valve into the left ventricle. from the left ventricle, the blood passes through the aortic valve to the aorta.

deoxygenated blood leaves through the right ventricle through the pulmonary artery. from the right atrium, the blood is pumped through the tricuspid valve (or right atrioventricular valve), into the right ventricle.