Define keywords: anaerobic respiration, oxygen debt, fermentation

Anaerobic respiration is respiration using electron acceptors other than molecular oxygen (O2). Although oxygen is only not the final electron acceptor, the process still uses a respiratory electron transport chain.

Oxygen debt is a cumulative deficit of oxygen available for oxidative metabolism that develops during periods of intense bodily activity and must be made good when the body returns to rest

Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In the context of food production, it may more broadly refer to any process in which the activity of microorganisms brings about a desirable change to a foodstuff or beverage.[1] The science of fermentation is known as zymology.

Explanation:

In aerobic organisms undergoing respiration, electrons are shuttled to an electron transport chain, and the final electron acceptor is oxygen. Molecular oxygen is a high-energy [2] oxidizing agent and, therefore, is an excellent electron acceptor. In anaerobes, other less-oxidizing substances such as nitrate (NO3-), fumarate, sulphate (SO42-), or sulphur (S) are used. These terminal electron acceptors have smaller reduction potentials than O2, meaning that less energy is released per oxidized molecule. Therefore, anaerobic respiration is less efficient than aerobic.