Difference between Photosynthesis and Cellular Respiration

When you go through the concepts of cellular respiration and photosynthesis, you are bound to find some striking similarities. Nonetheless, fundamentally they are quite different from one another.

Before we head straight to the differences between respiration and photosynthesis, let’s become familiar with the concepts. In turn, it will help to differentiate the two more effectively.

What is Photosynthesis?

It occurs only in cells that has chlorophyll and can only take place in the presence of sunlight. The said process uses water and carbon dioxide and produces oxygen and carbohydrates as by-products. 

It is noteworthy that light energy is changed into chemical energy during photosynthesis. Also, hydrogen released through photolysis is absorbed by NADP, which in turn gets reduced into NADPH2. 

It is expressed as 6CO2 + 6H2O –––> C6H12O6 + 6O2

Hence, Calvin Cycle forms an integral part of photosynthesis.

What is Cellular Respiration?

Essentially, it is an ongoing catabolic process. The process uses carbohydrates and oxygen and releases water and carbon dioxide as end products.

Notably, on oxidation, the energy released through carbohydrates and other vital substrates gets absorbed in ATP. Nevertheless, a fraction of energy is lost as heat amidst the process.

Furthermore, during the simultaneous process of oxidative phosphorylation, ATP molecules are produced from the oxidation of carbohydrates. Subsequently, synthesised ATP is used during various stages of the metabolic process.  

Additionally, glycolysis and oxidation of pyruvic acid take place during cellular respiration. It is expressed as C6H12O6 + 6O2 -----> 6CO2 + 6H2O

Are you still wondering - “How are photosynthesis and cellular respiration different?” Check below to know more.

Differences between Photosynthesis and Respiration

It must be noted that despite being a similar process, photosynthesis and respiration takes place in reverse. 

For instance, in photosynthesis, the input, namely, water and carbon dioxide, generate Glucose and oxygen as by-products. On the other hand, in cellular respiration, oxygen and Glucose release water and carbon dioxide as by-products.

Also, in photosynthesis, the sun’s light energy is first converted into chemical energy and is then stored in glucose bonds. Conversely, in cellular respiration, the chemical energy in Glucose is released to yield ATP.

Likewise, both follow a different metabolic process. For instance, photosynthesis follows an anabolic process. In the metabolic process, the carbon dioxide and energy produced from NADPH and ATP is utilised to create Glucose molecules. 

Similarly, cellular respirations follow a catabolic process. Glucose is broken down for the production of ATP, FADH2, NADH and carbon dioxide. 

Look at the table below to check out the fundamental difference between photosynthesis and respiration in a nutshell.



Cellular Respiration


It is concerned with the capture, conversion and storage of energy.

It releases energy. 


Carbon dioxide + water + light

Oxygen + Glucose

Metabolic process






Energy Source 



Electron Carriers



Occurs in

It is common in plants, photosynthetic bacteria, and algae. 

It occurs in all living organism


Oxygen and Glucose

Water and carbon dioxide


6CO2 + 6H2O -------> C6H12O6 + 6O2

C6H12O6 + 6O2 -----> 6CO2 + 6H2O

DIY: What are photosynthesis and cellular respiration? Explain in your own words. 

Similarities between Photosynthesis and Respiration

Despite the difference between photosynthesis and respiration, both processes are interdependent. Let’s take a quick look at the comparison between photosynthesis and respiration from the figure below. 

It also answers the query of – “What is the difference between respiration and photosynthesis?” in brief. 

Learn about the difference between photosynthesis and respiration in more depth by joining our live classes online. You can also gain a better insight into the relationship between photosynthesis and respiration by going through our latest PDF solutions. 

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FAQ (Frequently Asked Questions)

1. Differentiate between photosynthesis and respiration.

Parameters that distinguish between photosynthesis and respiration include – their reactants, metabolic process and by-products. In photosynthesis, water, light energy and carbon dioxide are the reactants which produce Glucose and oxygen. Alternatively, in cellular respiration, oxygen and Glucose react to produce water and carbon dioxide.

2. What is photosynthesis?

It is an anabolic process wherein the sun's light energy is captured, changed into chemical energy and stored in glucose bonds. Photosynthesis is expressed as - 6CO2 + 6H2O -------> C6H12O6 + 6O2

3. What is cellular respiration?

Cellular respiration is a catabolic process wherein the energy stored in glucose bonds is released to produce ATP.  It is expressed in the form of an equation as 6CO2 + 6H2O -------> C6H12O6 + 6O2.