Anaerobic Respiration

Based on availability of oxygen, cellular respiration may be divided into two types: anaerobic and aerobic respiration. Anaerobic respiration means in the absence of oxygen; while aerobic means in the presence of oxygen.

Anaerobic Respiration: The process of cellular respiration that takes place in the absence of oxygen is called anaerobic respiration. So, we can say that partial oxidation of food in the absence of oxygen, resulting in the release of some amount of energy, is called anaerobic respiration.

There is incomplete breakdown of respiratory substrate and thus little energy is relased.

$dpi{100} fn_jvn Glucose:(6;Carbon)xrightarrow[In;Cytoplasm]{Glycolysis}Pyruvic ;Acid :(3;Carbon)$

$Pyruvic :Acid overset{In: absence: of; oxygen}{rightarrow}Alcohol:+Carbon:dioxide:+:Energy$

Glucose $large (C_6H_1_2O_6)$ has six carbon atoms joined to each other by covalent bonds. Hydrogen and oxygen atoms are also attached to these carbon atoms. In anaerobic respiration of glucose, some hydrogen atoms are removed, resulting in its oxidation. At the end of a series of reaction, glucose gets converted into two molecules of pyruvate, which contains three carbon atoms.

The oxidation of glucose in a series of reactions leading to the formation of pyruvate is called glycolysis. Glycolysis means ‘splitting of sugar’. It takes place in all organisms, in the cytoplasm of the cell. It is the first stage of respiration – both aerobic and anaerobic.

After glycolysis, its product (pyruvate) gets converted into different compounds depending on the presence or absence of oxygen.

After glycolysis, further anaerobic reactions produce different products like lactic acid or ethanol (ethyl alcohol) in different situation. This step completes the anaerobic respiration of glucose. Anaerobic respiration resulting in the formation of lactic acid and ethanol is called ‘fermentation’. Examples are: lactic acid fermentation and alcohol fermentation.

Sample Questions

(More Questions for each concept available in Login)

Question : 1

Which of the following are correct ? (a) The process of cellular respiration that takes place in the absence of oxygen is called anaerobic respiration. (b) Glycolysis means ‘splitting of sugar’. It takes place in all organisms, in the cytoplasm of the cell. (c) Anaerobic respiration results in the formation of lactic acid and ethanol is called ‘fermentation’.
A. Only (a) and (b) is correct .	B. Only (b) and (c) is correct .	C. Only (a) and (c) is correct .	D. All of these .
Right Option : D
View Explanation

Question : 2

Anaerobic respiration is also termed as _______________
A. Fermentation	B. Imbibition	C. Transportation	D. All of the above
Right Option : A
View Explanation

Question : 3

Fermentation is a kind of anaerobic respiration done by bacteria and fungi .In it, food substrate lies outside the cell in a liquid medium and is oxidised to form organic acids of alcohol. This process is used in the manufacture of wine. The process used in manufacture of wine is a kind of _____________
A. Aerobic respiration	B. Anaerobic respiration	C. Process in which no energy is released	D. None of the above
Right Option : B
View Explanation