Aerobic Respiration

Oct 17, 2022, 16:45 IST

Respiration is one of the most important chemical processes that all living organisms, including plants, animals, and humans, perform to release the energy needed for life processes. The process of respiration occurs both in the presence and absence of oxygen.

For example, humans undergo the process of respiration by inhaling the oxygen gas and exhaling the carbon dioxide gas. Many other living organisms, including both plants and animals, undergo the process of respiration to obtain energy for their metabolic activities.

Respiration is of two types:

  • Aaerobic respiration
  • Anaerobic respiration.


The process of producing a cellular energy in the presence of oxygen is known as Aerobic Respiration”.

What is Aerobic Respiration?

An aerobic respiration is a biological process in which food glucose is converted into energy in the presence of oxygen. The chemical equation of aerobic respiration is given below –

Glucose (C6H12O6) + Oxygen 6(O2) → Carbon-dioxide 6(CO2) + Water 6 (H2O) + Energy (ATP)

The above chemical equation states energy is released by splitting glucose molecules using oxygen gas. At the end of a chemical reaction, energy, water molecules, and carbon dioxide gas are released as byproducts or end products. The energy of 2900 kJ is released while splitting the glucose molecule. This energy is used to produce ATP molecules - adenosine triphosphate, which the system uses for various purposes.

The process of aerobic respiration occurs in all multicellular organisms, including animals, plants, and other living organisms. During the process of respiration in plants, gaseous oxygen enters the plant cells through stomata located in the skin of the leaves and stem of the plant. Using the process of photosynthesis, all green plants synthesize their food and release energy.

Steps of Aerobic Respiration

The complete process of an aerobic respiration occurs in four different stages:

  1. Glycolysis

The primary step of an aerobic respiration is glycolysis and then takes place in the cytosol of the cell. During the process of glycolysis, glucose molecules are broken down into two molecules of ATP and two molecules of NADH, which are later used in the process of aerobic respiration.

  1. Formation of Acetyl Coenzyme A

The second step of aerobic respiration is the formation of acetyl coenzyme A. During this process, pyruvate is oxidized in the mitochondria and a 2-carbon acetyl group is formed. The newly formed 2-carbon acetyl group binds with coenzyme A to form acetyl coenzyme A.

  1. Citric Acid Cycle

The third step of aerobic respiration is the citric acid cycle, also called the Krebs cycle. In this phase of aerobic respiration, oxaloacetate combines with acetyl-coenzyme A to form citric acid. The citric acid cycle goes through a series of reactions and produces 2 molecules of carbon dioxide, 1 molecule of ATP and the reduced forms of NADH and FADH.

  1. Electron transport chain

This is the final step in aerobic respiration. In this phase, a large number of ATP molecules are produced by the transfer of electrons from NADH and FADH. One glucose molecule creates a total of 34 ATP molecules.

Key Points on Aerobic Respiration

  • An aerobic respiration uses oxygen to break down glucose, amino acids, and fatty acids to produce ATP.
  • Pyruvate is then converted to acetyl CoA in the mitochondrial matrix.
  • The Krebs cycle also occurs twice per glucose molecule.
  • The protein complexes are also arranged on the inner mitochondrial matrix so that electrons pass from one reacting molecule to another. This is called the electron transport chain.
  • ATP synthase also produces ATP from ADP and inorganic phosphate.

Frequently Asked Question (FAQs)

Q1. Do aerobic respiration require oxygen?

Ans. There are two types of respiration, i.e., aerobic and anaerobic respiration. One that takes place in the presence of oxygen is called aerobic respiration, Whereas aerobic respiration requires the presence of oxygen to produce energy from food.

Q2. What affects aerobic respiration?

Ans. The temperature, light, and materials of respiration, such as carbohydrates, fats, proteins, etc., affect the rate of aerobic respiration.

Q3. How is the energy released in aerobic respiration?

Ans. Glucose is oxidized to release energy, which is stored in ATP molecules.

Q4. Which gas is used for respiration?

Ans. Oxygen

Q5. In which process oxygen is not required?

Ans. Glycolysis, which is the first step in all types of cellular respiration is anaerobic and does not require oxygen.

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