What Are the Products of Photosynthesis

Photosynthesis is the name given to the set of chemical reactions performed by plants to convert energy from the sun into chemical energy in the form of sugar. Specifically, plants use energy from sunlight to react carbon dioxide and water to produce sugar (glucose) and oxygen. Many reactions occur, but the overall chemical reaction for photosynthesis is: 6 CO2 6 H2O light → C6H12O6 6 O2Carbon Dioxide Water Light yields Glucose Oxygen In a plant, the carbon dioxide enters via leaf stomates by diffusion. Water is absorbed through the roots and is transported to leaves through the xylem. Solar energy is absorbed by chlorophyll in the leaves. The reactions of photosynthesis occur in the chloroplasts of plants. In photosynthetic bacteria, the process takes place where chlorophyll or a related pigment is embedded in the plasma membrane. The oxygen and water produced in photosynthesis exit through the stomata. Key Takeaways In photosynthesis, energy from light is used to convert carbon dioxide and water into glucose and oxygen.For 6 carbon dioxide and 6 water molecules, 1 glucose molecule and 6 oxygen molecules are produced. Actually, plants reserve very little of the glucose for immediate use. Glucose molecules are combined by dehydration synthesis to form cellulose, which is used as a structural material. Dehydration synthesis is also used to convert glucose to starch, which plants use to store energy. Intermediate Products of Photosynthesis The overall chemical equation is a summary of a series of chemical reactions. These reactions occur in two stages. The light reactions require light (as you might imagine), while the dark reactions are controlled by enzymes. They dont require darkness to occur -- they simply dont depend on light. The light reactions absorb light and harness the energy to powder electron transfers. Most photosynthetic organisms capture visible light, although there are some that use infrared light. Products of these reactions are adenosine triphosphate (ATP) and reduced nicotinamide adenine dinucleotide phosphate (NADPH). In plant cells, the light-dependent reactions occur in the chloroplast thylakoid membrane. The overall reaction for the light-dependent reactions is: 2 H2O 2 NADP   3 ADP 3 Pi   light → 2 NADPH 2 H   3 ATP O2 In the dark stage, ATP and NADPH ultimately reduce carbon dioxide and other molecules. Carbon dioxide from the air is fixed into a biologically usable form, glucose. In plants, algae, and cyanobacteria, the dark reactions are termed the Calvin cycle. Bacteria may use different reactions, including a reverse Krebs cycle. The overall reaction for the light-independent reaction of a plant (Calvin cycle) is: 3 CO2   9 ATP 6 NADPH 6 H  Ã¢â€ â€™ C3H6O3-phosphate 9 ADP 8 Pi   6 NADP   3 H2O During carbon fixation, the three-carbon product of the Calvin cycle is converted into the final carbohydrate product.   VectorMine / Getty Images Factors That Affect the Rate of Photosynthesis Like any chemical reaction, the availability of the reactants determines the amount of products that can be made. Limiting the availability of carbon dioxide or water slows the production of glucose and oxygen. Also, the rate of the reactions is affected by temperature and the availability of minerals that may be needed in the intermediate reactions. The overall health of the plant (or other photosynthetic organism) also plays a role. The rate of metabolic reactions is determined in part by the maturity of the organism and whether its flowering or bearing fruit. What Is Not a Product of Photosynthesis? If youre asked about photosynthesis on a test, you may be asked to identify the products of the reaction. Thats pretty easy, right? Another form of the question is to ask what is not a product of photosynthesis. Unfortunately, this wont be an open-ended question, which you could easily answer with iron or a car or your mom. Usually this is a multiple choice question, listing molecules which are reactants or products of photosynthesis. The answer is any choice except glucose or  oxygen. The question may also be phrased to answer what is not a product of the light reactions or the dark reactions. So, its a good idea to know the overall reactants and products for the photosynthesis general equation, the light reactions, and the dark reactions. Sources Bidlack, J.E.; Stern, K.R.; Jansky, S. (2003). Introductory Plant Biology. New York: McGraw-Hill. ISBN 978-0-07-290941-8.Blankenship, R.E. (2014). Molecular Mechanisms of Photosynthesis (2nd ed.). John Wiley Sons. ISBN 978-1-4051-8975-0.Reece J.B., et al. (2013). Campbell Biology. Benjamin Cummings. ISBN 978-0-321-77565-8.