Question

How do fermentation and anaerobic respiration differ?

Answer 1

Hint: The type of respiration where energy is generated by the breakdown of the sugar molecules in the absence of oxygen is called anaerobic respiration.
The metabolic process that extracts energy from the carbohydrates by the action of enzymes in the absence of oxygen is called fermentation.

Complete answer:
The differences between fermentation and anaerobic respiration are-

Fermentation	Anaerobic Respiration
It is a type of metabolic reaction used to convert sugars like carbohydrates into- carbon dioxide and ethanol.	It is a type of cellular respiration where energy is generated through the breakdown of sugar molecules.
It occurs in the absence of oxygen but is induced by low oxygen concentrations.	It occurs completely in the absence of oxygen.
It uses various microorganisms and enzymes, hence, an extracellular process.	It occurs within the cytoplasm of the cell, hence, an intracellular process.
It is assumed to be the oldest metabolic process used by organisms to produce energy.	It is assumed to have evolved from fermentation in the process of evolution.
The amount of energy produced is less- 4 ATP molecules through glycolysis.	The amount of energy produced is more- 38 ATP molecules through glycolysis, citric acid cycle, and electron transport chain.
The final electron acceptor is- pyruvate, acetaldehyde, or any other organic molecule.	The final electron acceptor is- sulphate, nitrate, or sulphur. The process becomes aerobic if the terminal electron acceptor is oxygen.
Glycolysis is the major step occurring in this process.	Glycolysis is followed by the citric acid cycle and electron transport chain.
The substrates and the enzymes are obtained from the extracellular medium.	The substrates and the enzymes are exclusively intracellular.
It occurs in the microorganisms like- yeast, molds, or bacteria.	It occurs in the yeast or bacterial cells, human cells that respire without oxygen, etc.

Note: Fermentation and anaerobic respiration are evolutionary old processes as the earlier conditions on the atmosphere were anaerobic. Aerobic respiration evolved after the emergence of oxygen in the atmosphere. It is performed by higher organisms and is more energy-efficient.
Fermentation can also occur in the human cells in the absence of oxygen during fatigue. The end product in this process is lactic acid.