WHAT ARE THE DIFFERENCES BETWEEN PHOTOSYNTHESIS AND RESPIRATION? - BIOLOGY - 2025

The main difference between photosynthesis and respiration is that they are reverse processes. During photosynthesis, carbon dioxide and water enter the body, unlike respiration where these compounds are released.

Respiration is a complex process that includes the absorption of oxygen, the conversion of complex substances to carbon dioxide and water, and the release of energy. In contrast, in photosynthesis complex carbohydrates are built through simple substances such as carbon dioxide and water, at the same time that oxygen is released. That is why they are said to be inverse processes.

Photosynthesis (left) and respiration (right). Image on the right taken from BBC

Additionally, photosynthesis is the process in which green plants take in sunlight to convert it into sugar or glucose. Respiration is the process by which most cells break down sugar / glucose to be used for energy.

On the other hand, photosynthesis and respiration are complementary processes in which living organisms obtain substances they need. The two processes consume and create the same substances: water, glucose, oxygen, and carbon dioxide, but they do it differently.

8 differences between photosynthesis and respiration

1- Use of carbon dioxide and oxygen

As mentioned earlier, during respiration oxygen is used and carbon dioxide and water are formed. Instead, during photosynthesis, carbon dioxide and water are used while oxygen is transformed and released.

2- Organisms where the process takes place

Respiration occurs in all cells of living organisms, including those that have chlorophyll and are green in color and those that do not have that particularity. Photosynthesis only occurs in organisms whose cells have chlorophyll.

3- Sunlight

On the other hand, photosynthesis only occurs when there is sunlight, while respiration occurs in light and dark conditions.

4- Metabolic pathways

In respiration, glycolysis occurs in the cytoplasm. In photosynthesis, light reactions occur in the grana of the chloroplast. During respiration, the citric acid cycle or Krebs cycle occurs in the mitochondrial matrix. The electron transport chain takes place in the mitochondrial membrane.

On the other hand, the dark reactions of photosynthesis happen in the stroma of the chloroplast. Additionally, photolysis or separation of water is done in the thylakoid lumen.

5- catabolic and anabolic process

Respiration is a catabolic process that includes the destruction of food or stored energy and the absorption of oxygen. Instead, photosynthesis is an anabolic process that includes the manufacture of food or energy where oxygen is released.

6- Carbohydrates

In the process of respiration carbohydrates are oxidized; in photosynthesis carbohydrates are synthesized. Energy is released during respiration, making it an exothermic process. During photosynthesis, energy is stored, turning it into an endothermic process.

7- Energy

Energy is released in the breath in the form of ATP. For its part, in photosynthesis, solar energy is stored in the form of glucose or chemical energy.

8- Weight of the plants

Conversely, during respiration the weight of dry plants decreases. During photosynthesis, the weight of dry plants increases. Additionally, in respiration, potential energy is converted into kinesic energy. During photosynthesis, solar energy is converted into potential energy.

The photosynthesis process

The process of photosynthesis is used by plants and other organisms to convert solar energy into chemical energy. This energy can then be released to be used as fuel for the activities of other organisms. Chemical energy is stored in carbohydrate molecules that are then synthesized from carbon dioxide and water.

Most plants, including algae and cyanobacteria, are capable of photosynthesis. For this reason they are called autotrophic organisms; that is, they synthesize substances to make food.

Photosynthesis is largely responsible for producing and maintaining the oxygen content of the planet Earth's atmosphere. It is also responsible for producing most of the organic compounds and most of the energy necessary for life on the planet.

conclusion

Photosynthesis only occurs in cells that have chlorophyll during daylight. This process uses carbon dioxide and water to be carried out; carbohydrates and oxygen are released.

Solar energy is converted into chemical energy in the form of carbohydrates. During photosynthesis, ATP molecules are synthesized by the conversion of solar energy. The released hydrogen is accepted by NADP and is reduced to NADP2.

The synthesized ATP is used during the dark reaction of photosynthesis and all processes occur in the chloroplast. The rate of photosynthesis is 20 times faster than that of respiration.

The breathing process

This process consists of metabolic reactions that take place in the organisms of the cells. In this process, biochemical energy from nutrients is converted into ATP. The reactions involved in respiration are catabolic reactions that break down large molecules into smaller molecules.

During this process, energy is released and it is one of the ways in which a cell releases chemical energy as fuel for cellular activity.

Cellular respiration is considered an exothermic reaction since heat is released when it takes place. This chain of reactions occurs through various steps or biochemical processes.

Nutrients that are usually used in respiration generally include glucose, amino acids, and fatty acids. The most common oxidant is oxygen.

conclusion

Respiration takes place in all living cells of a plant. It is also a catabolic process that continues throughout the day and night. Respiration uses oxygen and carbohydrates; the end products of respiration are carbon dioxide and water.

The energy released from carbohydrates is trapped in ATP during oxidation. However, some energy is lost in the form of heat. The oxidation of carbohydrates releases molecules of ATP, the energy that is stored in living organisms. The ATP synthesized during respiration is used in various metabolic processes.

Hydrogen released during carbohydrate oxidation is trapped in hydrogen receptors. Glycolysis takes place in the cytoplasm and acid oxidation in the mitochondria. Generally, the rate of respiration is slower than that of photosynthesis.

References

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