Is Prana oxygen only? No, oxygen is part of Prana, but prana is much more than that. It is all that we inhale from air, surcharged with the vitality of Solar Energy, plus high energy ionising Cosmic rays, plus ionising radiations from Uranium, Thorium, Potassium and radon/thoron radio-active gases always present in the air, plus all those life giving nuclei present in the air, not yet fully understood.
Prana is also contained in the food we take, prana is also present in the water we drink and the surcharged water, besides providing minerals, is also ionised to some extent, charged by total solar energy spectrum etc. Similarly, all vegetables, fruits and other food stuff are of different colours and hues thus loaded with vast spectrum of energy which imparts vitality to our body; and also by the vitamins and minerals, carbohydrates and protiens present in them.
And, as an illustration of the part played by both positively and negatively charged electrons and ions in life processes, it may be noted that it is the negatively charged male sperm which is able to fertilise the female ovum, to create new life.
And to create ionisation in our body, God has provided potassium as a necesary part of our body cells, and one of the potassium isotopes is K-40 which is radioactive thus able to create ions/electrons useful in life processes, besides production of ions in our body by other processes. For example, glucose, in the process of giving metabolic energy to the body gets first converted into pyrovate (C3H3O6) which is negatively charged product of glucose. This is to cite just one example.
And let us not forget the so much talked about oxidants - the positively charged oxygen molecules, which when let loose, become damaging like a rogue elephant, and we are asked to gulp vitamin 'C' and 'E' - the so called anti-oxidants which neutralise these oxidants. Thus, it is seen, that both negatively and positively charged ions play a very significant part in life processes.
Thus, Prana is a dynamic life sustaining force.