Introduction

Respiration is the cellular energy-yielding process that occurs across the life domains (bacteria, archaea, eukaryota).

Aerobic respiration, as opposed to anaerobic respiration, occurs in the presence of oxygen, accounts for most respiration that takes place, and produces up to 15 times more ATP molecules.

Its overall reaction is:
glucose + oxygen –> carbon dioxide + water + heat energy

You can notice that it is essentially the reverse of photosynthesis. Of course not all organisms obtain their respiration substrate (e.g. glucose/food) by making it themselves as plants do, yet all carry out respiration. Don’t make the mistake of associating plants with photosynthesis, and non-plants with respiration. They are different processes. Plants photosynthesise and respire at the same time, we eat plants and respire at the same time.

Similarly, don’t confuse respiration with ventilation. In the context of biology, ventilation is the movement of air through our respiratory system i.e. breathing, while respiration is the process by which our cells produce energy (ATP).