Difference Between Respiration and Photosynthesis

Respiration vs Photosynthesis

These are the two of the most important processes of life. Without any of either respiration or photosynthesis, the world would be a miserable place without life. These two fascinating processes are different from each other in many ways, and those are concisely and precisely discussed in this article. Primarily, one of these processes converts the unusable energy into food while the other process makes serviceable form of energy from that stored food. In addition, both processes involve carbon dioxide but in different places. Therefore, it is always interesting to study respiration and photosynthesis.


Respiration is a biochemical process that converts food into energy with oxygen, and it takes place inside the cells of all living beings. In respiration, the biochemical energy of food is converted into adenosine triphosphate (ATP) and carbon dioxide using oxygen. Carbon dioxide is the waste product and the main product of ATP is the usable form of energy for organisms. Therefore, respiration could be stated as the main mean of obtaining energy that will be useful to maintain all the biological processes. Hence, it could be stated that food is burnt inside cells to produce energy through respiration. Sugars (glucose), amino acids, and fatty acids are amongst the highly used respiratory substrates in respiration. It is important to notice that the respiration process could be either aerobic or anaerobic depending on the involvement of oxygen in the process. Aerobic respiration process uses oxygen as the final electron acceptor while anaerobic respiration makes use of other chemicals such as sulphur compounds to generate energy. The entire process of respiration involves four major steps known as glycolysis, oxidative decarboxylation of pyruvate, citric acid cycle (Krebs cycle), and oxidative phosphorylation. After all the processes been taken place, there would be a net amount of 38 ATP molecules produced from one glucose molecule (C6H12O6). However, due to leaky membranes and efforts spent in moving some molecules during the process, the net production limits to around 30 ATP molecules from one glucose molecule.


Photosynthesis is the biochemical process that converts the energy of sunlight into organic compounds using carbon dioxide. Carbon dioxide (CO2) reacts with water (H2O) in the presence of sunlight to form glucose (C6H12O6) and oxygen (O2). Photosynthesis occurs in the chloroplast of the cells of plant, green algae, and many species of bacteria. Because of the photosynthesis, the global CO2 level is maintained at a low level, and it improves the O2 level of the atmosphere. However, the recent anthropogenic activities have detrimental effects on the photosynthetic purification of CO2 in the atmosphere. The green colour of the chlorophyll in the chloroplast is responsible for capturing sunlight at the desired level for the process of activation of electrons. There are two major steps in photosynthesis known as light reaction and dark reaction; light reaction involves Z-scheme and water photolysis while the dark reaction involves Calvin cycle and carbon concentrating mechanisms. The efficiency of the entire process of the photosynthesis is estimated to be varying around 3 – 6%. However, it depends mainly on the level of carbon dioxide in the atmosphere, light intensity, and temperature.


What is the difference between Respiration and Photosynthesis?

• Respiration is taking place in all the living beings, but photosynthesis occurs mainly in plants and other organisms with chloroplasts.

• Oxygen is released in photosynthesis while it is consumed in respiration.

• Carbon dioxide is released in respiration while it is consumed in photosynthesis.