Introduction

Earth is the only planet so far known where life exists. Life on Earth is in the form of plants, animals, and microorganisms. All these living entities do certain biological activities to keep themselves alive and to keep the cycle of life continuing on the earth. These processes or activities are nutrition, respiration, transport, control, coordination, growth, movement, and reproduction. All these processes are related to each other. One of the important biological processes is nutrition as it causes growth and development. The following article is about photosynthesis vs cellular respiration. Both processes although different are interdependent with each other.

Photosynthesis is the process by which plants obtain nutrition. In photosynthesis, solar energy from the sun is bound to glucose in the form of potential energy. This energy is used in the physiological work of plants. Other organisms absorb this energy directly or indirectly through food and use it to survive. That means the presence of living things on Earth depends on photosynthesis (2) & (3).

On the other side, cellular respiration is a biochemical process that produces energy from food absorbed by the body. Thus the main discussion is how photosynthesis and cellular respiration are interrelated and their similarities and differences (1) & (4).

Photosynthesis

Photosynthesis is a physiological process where a plant produces simple sugars for their nourishment. In this process, the plants absorb water and carbon dioxide from the environment and collect them in the leaf of mesophyll tissue. And produce simple sugars (glucose) as a main product and water and oxygen as a by-product via a chemical reaction. In other words, photosynthesis is a process that converts solar energy to potential energy into glucose.

The water produced in this process participates in metabolism and oxygen is released into the environment. The photosynthesis process occurs in all green chlorophyll-pigmented cells. In the case of plants, green leaves are the main organ of photosynthesis. The mesophyll tissue of the leaf has the highest number of chloroplasts and the highest amount of stomata, therefore, is the ideal place for photosynthesis. Photosynthesis also occurs on the young green stems of plants, on the green aerial roots of orchids, in the bodies of euglena, chrysamoeba, etc.

The chemical equation of photosynthesis is

6CO₂ + 12H₂O → C₆H₁₂O₆ + 6O₂ + 6H₂O

Cellular respiration

Energy is essential for the survival of the organism. Food (glucose) is the source of energy production in cells.  Most living things require oxygen (air) to get energy from food. This oxygen reacts with the molecules present in the body’s cells and burns the molecules slowly to release energy. The released energy is stored in the ATP (Adenosine triphosphate) molecules within the cell. The body can use this stored energy at its own discretion. Cellular respiration is continuously (day & night) happening in every single cell of every kind of organism from unicellular to multicellular. The glycolysis stage of respiration occurs in the cytoplasm of the cell and the phase of the Krebs cycle occurs in the cell mitochondria

The biochemical processes in which food is fully or partially oxidized in the presence or absence of oxygen and the potential energy present in the food is released as kinetic energy and produces ATP is called cellular respiration. The energy produced by cellular respiration is used for the biological functions of the body. The oxygen needed for cellular respiration is collected from the surrounding environment (1) & (2). The chemical equation of cellular respiration is

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (686 kcal)

The relation between photosynthesis and cellular respiration

The process of photosynthesis and cellular respiration are interdependent. Both processes have similar reactions, but both processes occur in completely opposite ways.

• In cellular respiration, oxygen and glucose react to produce water and carbon dioxide.
• Whereas in photosynthesis plants absorb carbon dioxide and water from the environment to produce glucose and oxygen.
• The carbon dioxide required for photosynthesis is produced by cellular respiration.
• The glucose that is required for cellular respiration is produced by the process of photosynthesis.

So both processes are completely dependent on each other. During the day, photosynthesis and cellular respiration of green plants occur together. So cellular respiration and photosynthesis are both related. However, in many cases, some differences are observed between these two biological processes. The differences between these two biological processes (photosynthesis & cellular respiration) are described below (2).

Difference between photosynthesis and cellular respiration

Photosynthesis and cellular respiration are both physiological processes. These two processes complement each other. Before analyzing the differences between them, some similarities between the two processes are discussed (2) & (3).

Similarities

1. Energy is produced in both photosynthesis and cellular respiration.
2. Oxidation and reduction occur together in the process of photosynthesis and cellular respiration. So these two physiological processes are called oxidation-reduction reactions.
3. These two biological processes are involved in the exchange of gases. In the process of photosynthesis, carbon dioxide is absorbed and oxygen is released. On the other hand, oxygen is absorbed and carbon dioxide is released.
4. ATP is produced in both photosynthesis and cellular respiration.
5. These two processes can carry electrons. These two processes are used as electron transport chains.
6. At the end of both processes, energy is generated which is used in all living cells to carry out daily activities.

Now let us know the difference between photosynthesis and cellular respiration.