Question: Why can we not survive without oxygen?

Roisin Jones answered on 11 Nov 2016:

Basically, oxygen is essential to us because our bodies use it in our cells to convert energy from nutrients in the food we consume into a molecule called ATP, which is the chemical that our body uses to transport energy for all our vital bodily functions. If we ran out of energy, our bodies wouldn’t be able to do important things, like breathing and keeping our hearts beating, so we would die, hence the importance of oxygen!