Photosynthesis Vs. Cellular Respiration the Major Processess in a Global Balance

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Updated: Nov 30, 2023
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Photosynthesis Vs. Cellular Respiration the Major Processess in a Global Balance

This essay will compare and contrast photosynthesis and cellular respiration, two fundamental biological processes. It will discuss their roles in the global carbon cycle and their importance in maintaining ecological balance. The piece will explain how these processes are interconnected and vital for life on Earth. PapersOwl showcases more free essays that are examples of Biotechnology.

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There are two key processes that occur in nature to obtain energy, they are photosynthesis and cellular respiration. The derivative of the word photosynthesis is the process in which energy of sunlight is converted by plants to store chemical energy in carbohydrate bonds. Photosynthesis is known to be performed by plants, as is cellular respiration. Cellular respiration is organisms obtaining energy from a conversation that releases energy when oxygen is present. These two processes work together hand in hand as a global balance since they are reactants of each other.

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Despite this, there are also differences possessed between these 2 processes. Cellular Respiration is when oxygen and glucose are taken in and covered into ATP energy in the Mitochondria, ATP energy fuels the cells and provides energy in the body. There are three stages of cellular respiration, glycolysis, Krebs cycle, and electron transport chain. In order for cellular respiration to take place two things are needed oxygen and glucose., once you have those two ingredients the first stage glycolysis, takes place.

Glycolysis is breaking up glucose molecules and turning them into pyruvic acids this process uses two ATP molecules but then produces four more ATP molecules along with two NADH molecules (which helps with making ATP). Since glycolysis only needs glucose to work and not glucose and oxygen this makes it an anaerobic process meaning it doesn’t need oxygen, unlike the next 2 stages. Stage two of cellular respiration is the Kreb cycle which does require oxygen making it aerobic. The Krebs cycle takes place in the mitochondria, it takes the two pyruvate molecules that were in the previous cycle to then turn them into two ATP molecules, they do this by oxidizing (or adding oxygen to) the pyruvates which then makes CO2, which is why we breathe out CO2, this all creates a by-product of two more NADH molecules. Enzymes also play a big role here, adding any additional phosphate to ADP then resulting in more ATP molecules. The reason why its a cycle is because the enzymes create a four-carbon molecule called Oxaloacetic acid which then forms a six carbon molecule called citric acid which is then oxidized which then cuts off carbons and returns back into the oxaloacetic acid leaving leftover CO2 which is exhaled. Some energy is made during that process, mainly being NAD+ and FAD both hold onto high energy electrons until they can be released into the electron transport chain.

The electron transport chain is where the NADH and other byproducts of the Krebs cycle are put to work and make ATP, those byproducts provide the energy to push protons through a protein channel called ATP synthase which turns the ADP and Phosphates into ATP. There are two stages of photosynthesis, the first stage is harboring sunlight and turning that sunlight into energy through a series of chemical reactions and the second stage is the plant actually using that harbored energy for its own needs. In order for photosynthesis to occur it needs three things, water, CO2, and sunlight. Water comes in from the roots, and CO2 from the little pores on the leaves called stomata. Sunlight is absorbed through the chlorophyll which is inside the chloroplast. Once all the ingredients involved in photosynthesis are together then the first stage is ready to being, this stage takes part mainly in the chloroplast. Stage one is light dependent meaning it needs light energy in order to take place, first, the sunlight enters the chlorophyll, then an electron takes that sunlight resulting in photosystem II beginning. During photosystem II the electron with the sunlight begins the electron transport chain which is when the energized electron is transported through a mobile electron carrier.

By separating the electron the chlorophyll then replaces that missing electron by breaking apart the H2O molecules and stealing an electron from it, but by breaking the water molecule oxygen is then released into the world allowing us to breathe. Once the energized electron is in the electron mobile carrier it is sent to the cytochrome complex which pumps extra protons into the thylakoid (another structure in the chloroplast). This then charges the thylakoid which then makes all the protons within the gradient want to get away from one another which causes them to push into the enzyme called ATP Synthase which produces ADP which then becomes ATP with an added phosphate. Now the plant enters photosystem I which makes NADPH and NADPH+ that like ADP, is used to carry around energy. This is the end of the first stage of photosynthesis and now the second stage begins with light-independent reactions this is the stage where the plant takes all of the energy it has converted and harbored to do something beneficial for the plant. What takes place within this stage is the Calvin cycle which takes part in the chloroplast’s stroma, this cycle is composed of 3 stages that enable the plant to receive all the organic products it needs by utilizing ATP and NADPH and ultimately producing Glucose. Those 3 stages are Carbon fixation, Reduction, and Regeneration.

Carbon fixation is essentially when Carbon Dioxide is infused with an organic molecule. Reduction is when the organic molecule’s size decreases through the use of electrons, which is supplied by NADPH. The final stage is Regeneration, and its purpose is to allow the cycle to continue by recycling G3P to regenerate RuBP using ATP and other complex reactions. The process of Photosynthesis and Cellular Respiration creates a balance that is essential on Earth. While Photosynthesis deposits oxygen on earth, Cellular Respiration utilizes that oxygen. Due to them being the opposite equations of each of each other, they have one another’s reverse effect. While the Photosynthesis equation is: C6H12O6+6O2 the equation for Cellular Respiration is instead 6H2O+6CO2. This is the reason why plants are vital to any animal cell survival. Since photosynthesis is when light energy is made into chemical energy and cellular respiration is the use of that energy after being broken down, this means that photosynthesis is to produce food molecules for plants only using sunlight.

Whereas cellular respiration uses molecules from sugars to get the energy that stores ATP molecules and occurs all the time. It has also been found that photosynthesis can only occur within some bacterias and plants, but cellular respiration has the ability to occur in any living organism. With these 2 processes, they use different materials like oxygen or carbon dioxide as a by-product. Photosynthesis namely creates glucose and releases oxygen as a by-product through the use of carbon dioxide, light from the sun and water. Cellular respiration uses glucose and oxygen to create carbon dioxide as a by-product. Therefore, the processes of cellular respiration and photosynthesis can be compared. Contrary to popular belief, Photosynthesis is more essential to life than Cellular Respiration. Not only does Photosynthesis maintain and produce the oxygen that is used by Cellular Respiration but, it also is the process that allows for new energy to become accessible to life on Earth. Photosynthesis also maintains carbon dioxide levels in the environment, hence if levels of Carbon Dioxide were to increase or decrease, then catastrophic consequences to Earth will occur. Energy is important as it allows cellular respiration to begin and is crucial for the survival of living organisms on earth, this is produced through the process of photosynthesis. Energy also provides organisms with all of the important nutrients indirectly or directly. No organism can live without oxygen or energy, thus life without Photosynthesis is simply impossible.

As a result, the two processes in nature used to obtain energy are a key to the way we live our lives as they prove to be helpful to us in many instances. However, in order to be of this much importance to the world and organisms, we have had to realize that photosynthesis and cellular respiration has both went through a sequence of events to be of use to us. Cellular Respiration is vital for organisms to perform regularly in dynamic equilibrium by using oxygen, meaning photosynthesis has the ability to produce food for us and oxygen. To review this means that it is a balance necessary on earth as they are reactants of one another. These findings suggest that life can be obsolete without them, a world without these two processes is a world without life, so what we have now would not be sustained, but thanks to these processes we don’t need to worry about that. Maybe, further research should be done on this topic so that we can figure out in what other ways these processes are possible, in the case that these processes cycles halt.


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Photosynthesis vs. Cellular Respiration The Major Processess in a Global Balance. (2020, Feb 17). Retrieved from