Differences between Photosynthesis and Cellular Respiration

This is FREE sample
This text is free, available online and used for guidance and inspiration. Need a 100% unique paper? Order a custom essay.
  • Any subject
  • Within the deadline
  • Without paying in advance
Get custom essay


Photosynthesis is the chemical reaction that intakes solar radiation or (light energy), carbon dioxide and water and outputs organic food molecules (sugar) and oxygen for the Autotrophs (plants). Autotrophs need these organic molecular molecules or materials to allow for cellular work to be conducted. Which leads us to the process of Cellular respiration (Simon, Dickey, & Reece, 2019).

Cellular Respiration

Being a multi-stage work process that produces food energy for autotrophs using the output of photosynthesis as the input to kick-start work. The first step of this multi-step process is to glycolysis. Through glycolysis, cells come to breaks down glucose into pyruvic acid, and then the pyruvic acid, two molecules of ATP and two electrons that are stored in NADH. The second step of cellular respiration is the citric acid cycle. In this step the remaining glucose is transformed into carbon dioxide, producing some ATP, NADH, FADH2 molecules. The last step being the electron transport chain which uses the electrons stored in the NADH molecules to push NAD+ through the mitochondrial membrane producing H2O. With the backstock of H+ on the membrane ADP molecules synthases into ATP molecules (Simon, Dickey, & Reece, 2019).


A big difference between photosynthesis and cellular respiration is in who can perform these processes. Autotrophic beings’ (plants or bacteria) can perform the process of photosynthesis. On the other hand, every other organism including autotrophs conducts the cellular process of cellular respiration. The second difference between these two processes is that respiration can occur in any lighting conditions. Photosynthesis requires light energy in order to process carbon dioxide and water molecules, into glucose and oxygen. A third difference is viewed by what each process requires to conduct these cellular processes, thereby changing the final product produced. Simple put, cellular respiration uses oxygen (intake) to form carbon dioxide and water molecules (output). Whereby photosynthesis uses carbon dioxide and water molecules (intake) to produce oxygen (output) molecules. A fourth difference is cellular respiration is considered an exothermic process being that energy is released vice photosynthesis which is an endothermic process that stores energy (Simon, Dickey, & Reece, 2019).


Though my time on this planet has been short compared to the planet or celestial beings I have a view one common notation. This notation that I speak of is harmony in nature or how nature comes to find itself in a state of equilibrium through symbiotic relationships. One such symbiotic relationship can be viewed by producers/autotrophs and consumers/heterotrophs.

Starting this comparison, the products produced as an output from each auto- or heterotroph becomes the reactant required for each other, thus a never-ending cycle is created. Through photosynthesis, autotrophs create the glucose molecules that are used in cellular respiration to make ATP (Simon, Dickey, & Reece, 2019).

ATP is the currency of all cellular work within an organism. Without this ATP or Adenosine Triphosphate, no cellular process would be conducted in any organism. The byproduct of heterotrophs being carbon dioxide is required to conduct photosynthesis (Simon, Dickey, & Reece, 2019).

Water molecules are broken down to form oxygen molecules during photosynthesis, whereas in cellular respiration oxygen is combined with hydrogen to form water. While photosynthesis requires carbon dioxide and then releases oxygen, cellular respiration requires oxygen and comes to releases carbon dioxide. The oxygen that we breathe, and most other organisms breathe is utilized through our cells to conduct cellular respiration. Cellular respiration works best in the presence of oxygen. Without oxygen, much less ATP would be produced (Simon, Dickey, & Reece, 2019).

Dinosaur Extinction and Photosynthesis

The brief article presented by National Geographic regarding the extinction of dinosaur’s or the end of the Cretaceous era is a different way of asking why we would die without oxygen (Dinosaur Extinction Information and Facts, 2017). The heterotrophs or dinosaurs at the time were reliant on the autotrophs/producers to manufacture breathable air and a source of food for some dinosaurs. Without the suns, visible light autotroph became unable to produce breathable air. In the article, the author explains that researchers have two theories regarding why this era ended. Whether you accept a series of volcanism or that a meteor crashed into the earth, massive clouds of soot eventually blocked out the sun’s light.

As light and light energy began to not make it through to the planet and the plants the chemical reaction photosynthesis stopped, but cellular respiration continued. As cellular respiration continues green-house gases begin to build in the atmosphere. This eventually led to temperatures decreasing and food sources to become non-existent (Module Notes).

Expressing why this connection between dinosaurs and photosynthesis is so important, let’s examine the process and material required to allow for photosynthesis. Simplified carbon, water, and light are required to conduct photosynthesis. Without the sun’s wavelength energy reaching the plants on earth, photosynthesis loses the driving catalyst required for the chemical reaction to occur (Simon, Dickey, & Reece, 2019).

Expressing this thought in a real-world application think of a serious gaming laptop producing extreme results. The laptop could be related to the plant, and the water and carbon molecules are the battery. Now the laptop will function without a charge or the light energy for some time but eventually, the laptop will need a recharge. This recharge cycle is relatable to day and night situations in the real world. Now, lets cut the power cord making the light energy or the recharge cycle unavailable to the laptop or plant. After some time has gone by the laptop or plant will begin to shut down and in the case of the plant begin to die (Simon, Dickey, & Reece, 2019). Thus connecting photosynthesis and the extinction of dinosaurs.


  1. Dinosaur Extinction Information and Facts. (2017, March 02). Retrieved September 15, 2018, from https://www.nationalgeographic.com/science/prehistoric-world/dinosaur-extinction/
  2. Module Notes: Cellular Respiration and Photosynthesis
  3. Simon, E. J., Dickey, J. L, & Reece, J. B. (2019). Campbell essential biology. 7th New York: Pearson.

Cite this paper

Differences between Photosynthesis and Cellular Respiration. (2021, Nov 17). Retrieved from https://samploon.com/differences-between-photosynthesis-and-cellular-respiration/

We use cookies to give you the best experience possible. By continuing we’ll assume you’re on board with our cookie policy

Peter is on the line!

Don't settle for a cookie-cutter essay. Receive a tailored piece that meets your specific needs and requirements.

Check it out