<span>Psychiatrist is a qualified medical doctor with post postdoctoral degree in Psychiatry. He studies Pharmacology, medicines and has authority to prescribe Antidepressant drugs. Against that Psychologist is qualified to take care of patients psychology. He helps patient by offering extensive psychotherapy and reduces patient's mental and behavioral suffering but psychologist is not authorized to prescribed antidepressant drugs.</span>
During the early days of the Earths life there was no oxygen but there was plenty of CO2 which the autotrophs took and used as food while discarding the excess which was the oxygen.
