What is Respiration?


Respiration is stated as the biochemical process that defines the chemical process that takes place within living organisms. This process results in the taking up of the bio molecules and their breakdown that supports in providing energy to the cells within organisms. However, the biochemical process is also known as metabolism as it includes both exothermic as well as endothermic chemical reactions. Therefore, it is understood that without the process of respiration within organisms it is impossible to survive.

Defining Respiration

In defining respiration, it is noticed that it is a process that occurs within a single cell in multicellular organisms thereby providing the energy for survival. This is a metabolic process that results in the formation of ATP or Adenosine. This occurs through the biochemical process, where the molecules of glucose are broken down thereby supporting in performing other functionalities among living organisms. There are two major types of respirations that include, aerobic and anaerobic respiration that occurs in several steps.

Types of Respiration

Figure 1: Aerobic Respiration and Anaerobic Respiration

In the process of respiration there lay two types of respiration processes that involves aerobic and anaerobic respiration.

Aerobic RespirationAnaerobic Respiration
Aerobic respiration is cellular respiration that occurs for producing energy in the presence of oxygen.Anaerobic respiration occurs when oxygen is not present.
In higher organisms, aerobic respiration is noticed and it takes place in both the cells of plants and animals.Anaerobic respiration takes place in lower organisms.
In aerobic respiration, varied gases are exchanged within the process.No exchange of gases is found during anaerobic respiration.
Aerobic respiration takes place in both the sites of mitochondria and cytoplasmAnaerobic respiration occurs only in the cytoplasm.

Table 1: Difference between Aerobic and Anaerobic Respiration

However, other than these, respiration may include external, cellular and internal.

Internal and External Respiration

Figure 2: internal and External Respiration

Both internal and external ways are found within organisms, the method where oxygen is taken from the external environment is referred to as the breathing of external respiration. However, there are a number of ways through which the living organisms take in oxygen from the environment.

Some organisms rely on specific organs for the exchange of gases or have a respiratory system. In mammals, the lungs are the respiratory organ present that exchanges oxygen. In mammals, external respiration takes place with the support of several mechanisms. The contraction and the release of the diaphragm in humans help in the display of the breathing rate.

Figure 3: Internal Respiration

Internal respiration refers to the involvement of blood as well as blood tissues that engages in the transportation of gases. The oxygen present within the lungs tends to diffuse within the air sacks that surround the capillaries containing the used oxygen thereby expelling it in the opposite direction whereas, blood tissues rich in oxygen get transported through the circulatory system within the lungs.

Cellular Respiration

Internal respiration results in obtaining oxygen with the usage of cells, which is referred to as ,cellular respiration. In order to gather energy, food is eaten by the organisms and the biological molecules that constitute the food further get broken down so that body can utilise it. In this process, glucose is broken down into ATP, providing energy to the body.

Stages of Respiration Within an Organism

Figure 4: Stages of Aerobic Respiration

In aerobic respiration, four stages are noticed that provided energy to the body of the organism. The four stages include glycolysis, Krebs cycle, link and lastly, oxidative phosphorylation. All of these supports in breaking down of food materials and proper utilisation of these molecules.

Importance of Respiration

Respiration is crucial for survival within organisms, as the intake of oxygen is necessary for breaking down food. This further supports in conducting of functionalities within organisms that help in the survival of the organisms on earth.


In this tutorial, the focus has been given to extensively explaining the process of respiration. In both higher and lower-level organisms, the process of respiration takes place. Intake of oxygen is necessary as it provides the body with other functionalities, resulting in the breaking down of food materials and the production of ATP.


Q1. What is defined as ATP?

Ans. The full form of ATP is Adenosine triphosphate that supports providing currency for energy within cells. This is primarily composed of several groups and is catered to an organic compound consisting of phosphate, sugar ribose and as well as adenine. Furthermore, it operates as a compound for providing energy to the cells for conducting varied biochemical processes.

Q2. What is meant by fermentation?

Ans. The term, fermentation refers to a series of chemical reactions or varied processes of metabolism that is mostly noticed in bacteria or yeast in order to obtain energy. This energy is required for conducting several biological processes. However, this also known as anaerobic respiration that is used in the production of many food products that includes yoghurt, and alcoholic beverages.

Q3. What is defined as glycolysis?

Ans. The basic stage of cellular respiration is known as glycolysis. This generally follows the biochemical pathway, in which the oxidation of glucose occurs producing a simple organic compound. This reaction of glycolysis takes place in the cell in the region of cytosol.

Updated on: 24-Apr-2023


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