3.5: True Respiration
The common misconception about plants is that their only energy-related metabolic process is photosynthesis:
CO\(_2\) + H\(_2\)O + energy \(\longrightarrow\) carbohydrates + O\(_2\)
However, as most eukaryotes, plants have mitochondria in cells and use aerobic (oxygen-related) respiration to obtain energy:
carbohydrates + O\(_\mathbf{2}\) \(\longrightarrow\) CO\(_\mathbf{2}\) + H\(_\mathbf{2}\)O + energy
Typically, plants spend much less oxygen in respiration than they make in photosynthesis. However, at nights plants do exactly the same as animals, and make only carbon dioxide!