Why did God make plants our oxygen source?
Well, for starters, pure oxygen is fatal to all animals. Oxygen is an extremely reactive element, and an overabundance would saturate the body beyond the needs of the cells. We don’t completely understand the mechanisms behind oxidative stress, but it’s apparent that the oxygen starts reacting with hydrogen in cell walls, forming hydoxyl. Hydroxyl is remarkably good at breaking up lipids, which is an important structural element of cell membranes. So pure oxygen = damaged cell membranes. Too much pure oxygen for too long = lots of dead cells. Enough dead cells = death. That’s why breathing gear, such as scuba equipment, mixes oxygen with nitrogen (or for greater depths, a nitrogen/helium mix called helidox), which is far more abundant in the atmosphere. Another reason is call absorptive atelectasis (I honestly don’t know if I spelled that right, but it’s close). Basically, the oxygen replaces nitrogen around the aveoli (the sacs in your lungs where gasses diffuse into the blood stream)
