All living things need oxygen to stay alive.Most plants and animals obtain oxygen from the air.When you breathe in, your lungs take in air and the oxygen is extracted.When you breathe out, you breathe out air which contains a gas called carbon dioxide.Carbon dioxide is a waste product.
All living beings require air especially oxygen for most of the living organisms.Carbon-dioxide is also required in plants to produce carbohydrates for energy requirements.In animals, oxygen is required.Oxygen is taken in the body and then supplied to various parts. IT is then taken in mitochondria in the cell.The F1 particles in the mitochondria produce energy using oxygen in the form of ATP and because of this the whole mechanism of the cell runs. So, conclusion is that all this is required for living beings for energy, energy, energy....Hope it helps