Photosynthesis is a complementary biochemical reaction. Cellular respiration is another. Both photosynthesis and respiration require the products that are produced by respiration. Together, these reactions allow cells to make and store energy. They also regulate atmospheric levels of carbon dioxide (CO2) and oxygen.
Cellular respiration
Combining oxygen with food molecules is a process where organisms convert the chemical energy contained in these substances into beneficial life-sustaining activities.
Photosynthesis, Cellular Respiration
Photosynthesis is an essential biological process in which carbon dioxide and oxygen are exchanged within a biosphere. Cellular respiration and photosynthesis are also necessary. Photosynthesis occurs in plants, using light, energy, water, and carbon dioxide to make glucose and oxygen. This process is crucial to all life on Earth. It provides energy, food, oxygen, and a source of nutrition to all living things. Photosynthesis is not the same as cellular respiration. Cellular respiration involves the breakdown of food.
Connecting Cellular Respiration and Photosynthesis
A crucial relationship exists between photosynthesis (photosynthesis) and the cellular respiratory system (cellular respiration). This relationship allows us to live as we know. The products of one process can be called the reactants of another. The equation of cellular respiration reverses photosynthesis.
Cellular Respiration: C6H12O6 + 6O2 – 6CO2 + 6H2O
Photosynthesis: 6CO2 + 6H2O – C6H12O6+ 6O2
Photosynthesis produces the glucose used in cellular metabolism to make ATP. After the glucose has been converted to carbon dioxide, it is used for photosynthesis. While photosynthesis uses water to produce oxygen, cellular respiration is where oxygen is combined and formed to make water. While photosynthesis creates carbon dioxide and releases it, cellular respiration requires oxygen and produces carbon dioxide. The oxygen released is used by us, and most other organisms, for cellular respiration. This oxygen is carried in our blood and into our cells. Oxygen allows cell respiration to continue in our cells. Cellular respiration functions best when there is oxygen. Without oxygen, ATP will not be produced as well.
Photosynthesis and cellular respiration are both crucial components of the carbon circle. The carbon cycle consists of the pathways by which carbon dioxide is recycled in our biosphere. While cell respiration releases carbon dioxide into the environment through cellular respiration, photosynthesis draws carbon dioxide from the atmosphere. Photosynthesis allows for the exchange of carbon dioxide (and oxygen)

How do cell respiration and photosynthesis combine?
Photosynthesis involves using light energy by plants to produce organic food (glucose) or oxygen simply from minerals, such as carbon dioxide and water. This transforms the Sun’s light energy into potential chemical energy, then stored in nutrients.
Every plant needs the energy to germinate, grow, thrive, produce seeds, and so on. The backward reaction happens when we eat nutrients. It is called cellular respiration. This occurs when glucose is oxidized to carbon dioxide, water, energy, and food (for walking or feeding, breathing, reproducing, etc.).
Photosynthesis takes place only in plants. However, cellular metabolism occurs in every living cell, from bacteria to humans.
In other words, photosynthesis is a chemical reaction that works together to benefit all living things on Earth. This is how solar energy stays on Earth via the food chains. It maintains life by starting with plants.
Why can’t cellular photosynthesis occur without cellular respiration?
It has to do with something called the carbon cycle.
Carbon is a vital resource. It is found in our food as the backbone of many biological compounds.
Carbon is present in all the foods you eat. Carbon dioxide is produced when you exhale the carbon dioxide after you have used the food. The carbon dioxide would then be released into the atmosphere. It would stay there until it was too late. This is where plants are helpful.
Apart from breathing, plants can also do photosynthesis. They use sunlight to capture carbon dioxide that you have exhaled and convert it into sugar which you can then eat again. Can you see the cycle? It would help if you had oxygen to be able to use your food, and photosynthesis produces oxygen.
Without the photosynthesis process occurring in the environment, our finite food supplies and oxygen supply would soon run out. This cycle of carbon keeps us alive.
How are photosynthesis and cellular respiration related?
The information for each process will show that reactants and products are both present. Although they are bi-products, oxygen and glucose – both products of photosynthesis – are required for cellular respiration. However, carbon dioxide is also a byproduct of cell respiration – which is necessary for photosynthesis.
This is how we can understand the relationship between cellular metabolism and photosynthesis. In other words, plants and other lifeforms that use photosynthesis depend upon organisms that resort to cellular respiration to carbon dioxide. These organisms, in turn, rely on the glucose obtained from plants to source their energy needs. One of the most significant similarities between photosynthesis and cellular respiration is the use of the electron transport chain for electron movement.
The photosynthesis-cellular respiration relationship also explains why the two are necessary for the presence of life on the planet. This relationship is summarized by the following: photosynthesis uses radiant energy from Sun to produce glucose. The same glucose is later used to create usable energy through cellular respiration.
Summary
The equation that governs cellular respiration is directly opposite photosynthesis.
Global photosynthesis, which is the exchange of carbon dioxide with oxygen through photosynthesis, helps maintain stable levels.