Here's why:

* Anaerobic means "without oxygen."

* Respiration refers to the process of converting food into usable energy (ATP).

Key points about anaerobic respiration:

* It is less efficient than aerobic respiration (which uses oxygen).

* It produces less ATP per glucose molecule.

* It can lead to the production of byproducts like lactic acid (in humans) or ethanol (in yeast).

Some organisms, like certain bacteria, rely solely on anaerobic respiration. Other organisms, including humans, can switch to anaerobic respiration temporarily when oxygen is scarce, like during intense exercise.