Molecular oxygen (O2) refers to two oxygen atoms bonded together. It's what we breathe in from the air around us for our cells to perform respiration.
Respiration: The process by which cells break down simple food molecules such as glucose and release energy they contain.
Oxidation Reaction: A chemical reaction where a substance loses electrons or gains oxygen; often involves burning or rusting.
Hemoglobin: An iron-containing protein in red blood cells that transports molecular oxygen from lungs to tissues throughout the body.