Photosynthesis and Cell Respiration

by Phiona Hiebert


  • Photosynthesis is the process where plants use energy from the sun to transform water, carbon dioxide, and minerals into organic compounds. Light independent photosynthesis is called the Calvin Cycle. First, when a plant obtains water, it absorbs it into its system through tissues called Xylem in the cell. Carbon Dioxide gets in and Oxygen gets out through tiny holes or pores called stomata. Individual photons from the sun are absorbed though chlorophyll. Chlorophyll are tiny green pigments that are found in the Chloroplasts of plants. Plant cells have plastids, which contain Chloroplasts. The energy from sunlight drives the reaction of carbon dioxide and water molecules to make sugar and oxygen. CO2 combines with the the stored energy in the chloroplasts through a chemical reaction to make glucose. The sugar is moved through tubes in the leaves to the roots, stems, and fruits of the plants. Then the sugar is distributed throughout the plant for specific uses. Some is used for energy, some is stored as starch, and some is built into plant tissue.

Cell Respiration

The point of cellular respiration is to harvest electrons from organic compounds such as glucose and use that energy to make a molecule called ATP. ATP in turn is used to provide energy for most of the immediate work that the cell does. ATP can be thought of as being like a small package of energy that has just the right amount of energy that can be used in a controlled manner. There are three main stages of cellular respiration: glycolysis, the citric acid cycle, and electron transport/oxidative phosphorylation.

Similarities and differences

Cell Respiration and Photosynthesis are a complementary process. Once photosynthesis is finished and has completed its process, oxygen is produced as a by product. Cellular Respiration converts the oxygen and sugar into carbon dioxide and water. During this process some energy is released to make ATP, and the rest is lost at heat. Some similarities are that both processes rely on movement of electrons for operation, both use electron transport chains in production of ATP, both use chemiosmosis to generate ATP, and ATP is a key molecule in each process. An obvIous difference of the two are the reactants. Cell respiration's are glucose and oxygen, and photosynthesis' are carbon dioxide and water. Another difference is the location these things take place. They take place in the chloroplasts for photosynthesis and mitochondria for cell respiration.