The relationship between photosynthesis and cellular respiration is such that the products of one system are the reactants of the other. Photosynthesis involves the use of energy from sunlight, water and carbon dioxide to produce glucose and oxygen. Cellular respiration uses glucose and oxygen to produce carbon dioxide and water. To emphasize this point even more, the equation for photosynthesis is the opposite of cellular respiration.
Humans, animals and plants depend on the cycle of cellular respiration and photosynthesis for survival. The oxygen produced by plants during photosynthesis is what humans and animals inhale for the blood to transport to the cells for respiration. The carbon dioxide produced during respiration is released from the body and absorbed by plants to help provide the energy they need for growth and development. This is the never ending cycle that sustains life on earth.
The process of photosynthesis is used by plants and other photosynthetic organisms to produce energy, whereas the process of cellular respiration breaks down the energy for use. Despite the differences between these two processes, there are some similarities. For example, both processes synthesize and use ATP, the energy currency.
Below are some of the similarities and differences between these two systems.
Similarities between Photosynthesis and Cellular Respiration
Reduction-Oxidation Reaction | ||
Electron Transport Chain (ETC) | ||
Synthesize ATP | ||
Utilize ATP | ||
Phosphorylation | ||
Electron Carriers |
Differences between Photosynthesis and Cellular Respiration
Occurs in… | Plants, Algae and Photosynthetic Bacteria | All living organisms |
Function/Purpose | Capture, convert and store energy – light energy from the sun is converted into chemical energy and stored in the bonds of glucose | Release energy – chemical energy stored in glucose is released to produce ATP for the cell |
Reactants/Inputs | Carbon dioxide, Water and Light energy | Glucose and Oxygen |
Metabolic Process | Anabolic - CO2 and energy from ATP and NADPH are used to build glucose molecules | Catabolic - glucose is broken down to produce CO2 and energy in the form of ATP, NADH and FADH2 |
Location | Chloroplast of the plant cell | Glycolysis occurs in the Cytoplasm while the Mitochondria is the site of the Kreb’s Cycle and Electron Transport Chain (ETC) |
Source of Energy | Sunlight | Glucose (sunlight is not required) |
Electron Carriers | NADPH | NADH and FADH2 |
Stages | Light dependent Reactions – Light energy and water are used to produce ATP and NADPH
Calvin Cycle – Carbon dioxide and the energy from ATP and NADPH are used to produce glucose | Glycolysis – Glucose is combined with ATP to produce pyruvate molecules, NADH and more ATP
Pyruvate Oxidation - Pyruvate molecules are broken down into Acetyl-CoA (2-carbon compound) and CO2 is produced Kreb’s Cycle – Acetyl-CoA is combined with 4-carbon molecules to form the 6-carbon citrate molecules used to generate NADH, CO2, FADH2 and ATP Electron Transport Chain – Energy stored in NADH and FADH2 during the Krebs cycle is used to generate ATP, Water, NAD+ and FAD |
Products/Outputs | Glucose and Oxygen | Carbon dioxide and Water |
Equation | 6CO2 + 6H2O –––> C6H12O6 + 6O2 | C6H12O6 + 6O2 –––> 6CO2 + 6H2O |
The cycle of photosynthesis and respiration maintains the balance of oxygen and carbon dioxide. Photosynthesis produces the oxygen to replenish oxygen that is used up by living organisms during respiration. Carbon dioxide produced during respiration is one of the reactants plants need to perform photosynthesis.
Photosynthesis and cellular respiration are both part of a mutually beneficial relationship. Cellular respiration cannot occur without photosynthesis, and photosynthesis certainly cannot occur without the help of its partner.
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 have 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 \[\longrightarrow\] 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, synthesized 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 \[\longrightarrow\] 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, generates 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 are utilized 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.
Parameters | Photosynthesis | Cellular Respiration |
Function | It is concerned with the capture, conversion, and storage of energy. | It releases energy. |
Reactants | Carbon dioxide + water + light | Oxygen + Glucose |
Metabolic process | Anabolic | Catabolic |
Location | Chloroplast | Mitochondria |
Energy Source | Sunlight | Glucose |
Electron Carriers | NADPH | FADH2 and NADH |
Occurs in | It is common in plants, photosynthetic bacteria, and algae. | It occurs in all living organism |
Products | Oxygen and Glucose | Water and carbon dioxide |
Equation | 6CO2 + 6H2O \[\longrightarrow\] C6H12O6 + 6O2 | C6H12O6 + 6O2 \[\longrightarrow\] 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.
Conclusion
This is all about the meaning, explanation, and difference between photosynthesis and respiration. Learn how both biological processes are different from each other in different aspects. Concentrate on the features of these biochemical processes to understand the differences perfectly.