The key difference between respiration and photorespiration is that respiration is a universal process occurring in all living cells, involving the breakdown of glucose o generate ATP. On the other hand, photorespiration is a specific process that occurs in plants during photosynthesis when there is a high oxygen concentration, leading to the wasteful oxidation of glycolate and the release of carbon dioxide
What is Respiration?
Respiration is the biological process by which living organisms, such as animals, plants, and microorganisms, obtain energy from organic molecules, typically through the breakdown of glucose. It is a fundamental process that enables the production of adenosine triphosphate (ATP), the energy currency of cells.
In animals, respiration generally refers to the exchange of gases, particularly oxygen (O2) and carbon dioxide (CO2), between an organism and its environment. This process occurs in specialized respiratory organs, such as lungs in mammals, gills in fish, or tracheal systems in insects.
What is Photorespiration?
Photorespiration is a metabolic process that occurs in plants under certain conditions when there is a shortage of carbon dioxide (CO2) and an excess of oxygen (O2) in the leaf cells. It is an inefficient process that competes with photosynthesis, the main process by which plants convert sunlight, carbon dioxide, and water into energy-rich organic molecules.
During photorespiration, instead of fixing carbon dioxide and producing energy-rich compounds, plants inadvertently consume energy and release carbon dioxide. The process primarily takes place in the chloroplasts of plant cells, particularly in the specialized cells known as mesophyll cells, where photosynthesis occurs.
Respiration vs Photorespiration
The major difference between respiration and photorespiration is given below:
| Respiration | Photorespiration | |
| Definition | The metabolic process that occurs in plants when there is insufficient carbon dioxide (CO2) and excess oxygen (O2) in the leaf cells. | The metabolic process occurs in plants when there is insufficient carbon dioxide (CO2) and excess oxygen (O2) in the leaf cells. |
| Location | Occurs in the mitochondria of cells in all living organisms. | Occurs specifically in the chloroplasts of plant cells, primarily in the peroxisomes and mitochondria. |
| Oxygen Requirement | Requires oxygen (O2) as the final electron acceptor in the electron transport chain. | Involves the release of oxygen (O2) in the presence of light and excess oxygen (O2) in the leaf cells. |
| Carbon Dioxide Exchange | Releases carbon dioxide (CO2) as a byproduct of the process. | Consumes oxygen (O2) and releases carbon dioxide (CO2) as a byproduct. |
| Energy Production | Produces ATP (adenosine triphosphate) as the primary energy molecule. | Consumes ATP and reduces the energy production of the plant. |
| Purpose | Generates energy for cellular activities, growth, and maintenance. | Acts as a wasteful process and reduces the efficiency of photosynthesis. |
| Examples | Occurs in both plants and animals. | Primarily occurs in C3 plants but can also happen in C4 and CAM plants. |
| Significance | Essential for the survival of cells and organisms. | Considered a wasteful process that reduces plant productivity and growth. |
| Overall process | Glucose + Oxygen → Carbon Dioxide + Water + Energy (ATP) | RuBP + O2 → 2PG (2-phosphoglycolate) + 3-PGA (3-phosphoglycerate) |