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Respiration – Introduction, Types, Steps & Importance

Aug 24, 2022

Physiological Metabolism Respiration 


Energy flow in ecosystem 

The food chain and food web facilitate the movement of energy. Plants collect sunlight with the aid of chloroplasts during the process of energy flow in the ecosystem. A portion of it is turned into chemical energy during the process of photosynthesis. When herbivores eat (primary consumers) plants as food, this energy is stored in various organic products and passed on to the primary consumers in the food chain. The chemical energy contained in plant products is then converted into kinetic energy, and chemical energy is degraded by heat conversion.  

The flow of energy in the ecosystem is one of the most important variables in survival of a large number of creatures. Solar energy is the principal source of energy for practically all species on Earth. It is amusing to learn that we only receive around half of the sun’s effective radiation on Earth. When we say effective radiation, we mean radiation that plants can employ to perform photosynthesis. 

Energy flow 
Energy flow 


The process of breathing in oxygen and exhaling carbon dioxide is generally referred to as respiration. However, the phrase is more strictly used to describe the chemical process that organisms employ to extract energy from food, which often entails the consumption of oxygen and the emission of carbon dioxide.  

Because respiration releases energy, it is the chemical inverse of photosynthesis, which utilizes the sun’s energy to create organic molecules. Because the vast majority of species need the oxygen produced by photosynthesis for respiration. Photosynthesis and respiration are ecologically linked.  

Respiration is a series of chemical processes that allow all living things to create the energy they need to survive. It is a biological process in which air flows between the external environment and the species’ tissues and cells. During respiration, oxygen is inhaled, and carbon dioxide gas is exhaled. A metabolic process occurs when an entity obtains energy by oxidizing nutrients and thereby releasing waste. 


The process of respiration necessitates the use of glucose to initiate the reactions that result in the conversion of energy and the subsequent production of carbon dioxide and water as byproducts. 


Respiration in plants  

  • Plants’ leaves, stems, and roots all participate in the respiration process. 
  • There is a very little amount of gas exchange that occurs at each portion. As a result, each component meets its own energy requirements. Stomata are small holes in the leaves that allow gaseous exchange to occur. 
  • Plants respire 24 hours a day, while photosynthesis happens only when there is light. 
  • The quantity of carbon dioxide emitted during the day is substantially lower than the amount of oxygen created by photosynthesis. 
  • It is not recommended to sleep under the tree at night since the extra carbon dioxide generated during respiration may induce suffocation. 

Respiration in roots  

  • It is the first phase in the nitrogen cycle. Atmospheric nitrogen (N2), which is accessible in an inert state, is transformed into the useful form -ammonia in this process (NH3). 
  • The inert form of nitrogen gas is deposited into soils from the atmosphere and surface waters during the nitrogen fixation process, mostly by precipitation. Later, the nitrogen undergoes a series of modifications that result in the separation of two nitrogen atoms, which mix with hydrogen to produce ammonia (NH4+). 
  • Diazotrophs is a symbiotic bacteria that complete the nitrogen fixation process. 
  • Other essential participants in this process are Azotobacter and Rhizobium. These bacteria have a nitrogenized enzyme that can mix gaseous nitrogen with hydrogen to produce ammonia. 
Respiration in roots 

Respiration in stem  

  • In the case of the stem, air diffuses into the stomata and passes through various regions of the cell to respire.  
  • The stomata also disperse the carbon dioxide emitted during this time. 
  • In woody or higher plants, lenticels are known to undertake gaseous exchange.  
 Respiration in stems

 Respiration in leaves  

  • Leaves have stomata, which are minute holes. 
  • Gaseous exchange happens by diffusion through stomata.  
  • Each stoma is regulated by guard cells. 
  • Gas exchange occurs as the stoma between the inferior of leaves and the atmosphere closes and opens.  
Respiration in leaves 

Types of respiration  

We classify respiration into two types based on the presence or absence of oxygen: 

  1. Aerobic Respiration 
  2. Anaerobic Respiration 
Types of respiration 

Aerobic respiration  

  • Aerobic respiration refers to respiration that happens in the presence of oxygen since ‘air’ contains oxygen.  
  • Aerobic respiration involves the use of oxygen to break chemical bonds in glucose, releasing large amounts of energy. It is an important source of energy for plants. 
  • All creatures that obtain energy through aerobic respiration cannot live in the absence of oxygen. This is due to the lack of oxygen; they cannot obtain energy from the food they ingest.  
  • Aerobic respiration requires more energy since it involves the entire breakdown of glucose while using oxygen.  
Aerobic respiration 

Anaerobic respiration  

  • Anaerobic respiration takes place within the cytoplasm of prokaryotic organisms such as yeast and bacteria.  
  • In this case, less energy is liberated due to incomplete oxidation of food in the absence of oxygen.  
  • Anaerobic respiration generates ethyl alcohol and carbon dioxide. 
Anaerobic respiration 

Steps involved in respiration in plant 

The process of respiration in plants consists of two fundamental steps: 

  • Glycolysis: The conversion of glucose into pyruvic acid via a sequence of enzyme processes during plant respiration. These reactions occur in the cytoplasm. This chain of processes is known as glycolysis. 
  • The Krebs’s cycle: This process involves the conversion of pyruvic acid into carbon dioxide, water, and energy. Pyruvic acid generated during glycolysis enters mitochondria. Several enzymes catalyze the processes, which result in the creation of CO2 and water. The Krebs cycle is a set of enzyme processes.  
Respiration in plants 

Importance of respiration  

  • Plants, like other creatures, breathe. Plants get their energy from respiration, which is a process in which glucose meal breaks down in the presence of oxygen to produce carbon dioxide and water, releasing energy. 
  • The plant uses this energy to carry out its numerous life activities. Plants, like other species, must respire in order to survive. Plant respiration varies from that of mammals. In other words, each part of a plant can takes in oxygen from the air, use it to make energy, and release carbon dioxide on its own.  


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