Oxygen produced during photosynthesis

The carbon dioxide comes from the air, and the water comes from the soil in which the plant grows. When a plant is watered or when it rains, water enters the root and is transported to the leaves by plant cells called xylem. To protect themselves against drying out, leaves have structures called stomata that allow gas to enter and leave. Stoma is from the Greek and means hole. Both carbon dioxide and the oxygen produced during photosynthesis pass in and out of the leaf through the opened stomata. 

In this brief overview, we ve seen that oxygen and carbohydrates are produced during photosynthesis, whereas they are consumed during aerobic oxidation. In both processes, the flow of electrons creates a electrochemical gradient, or proton-motive force, that can power ATP synthesis. As we examine these two processes at the molecular level, focusing first on aerobic oxidation and then on photosynthesis, the striking parallels between them will become evident. 

Plants, algae and cyanobacteria also respire, using some of the oxygen released during photosynthesis to burn the carbohydrates produced by photosynthesis and extract the stored energy from them. 

As shown in Fig. 10-13, there is also a flux of O2 produced during net photosynthesis from the ocean to the atmosphere and an export flux of particulate and dissolved organic matter out of the euphotic zone. For a steady-state system, new production should equal the flux of O2 to the atmosphere and the export of organic carbon (Eppley and Peterson, 1979) (when all are expressed in the same units, e.g., moles of carbon). Such an ideal state probably rarely exists because the euphotic zone is a dynamic place. Unfortunately, there have been no studies where all three fluxes were measured at the same time. Part of the difficulty is that each flux needs to be integrated over different time scales. The oxygen flux approach has been applied in the subarctic north Pacific (Emerson et al, 1991) and subtropical Pacific (Emerson et al, 1995, 1997) and Atlantic (Jenkins and Goldman, 1985). The organic carbon export approach has... 

Carbohydrates Ultimately, carbohydrates cire the product of photosynthesis, the process in plants that combines carbon dioxide, water, and energy with chlorophyll and other biomolecules to produce Ccirbohy-drates and release oxygen gas. The major carbohydrate formed during photosynthesis is glucose. Plants and animals sometimes combine simple carbohydrates such as glucose into more complicated carbohydrates such as stcirch, glycogen, and cellulose. 

Carbon-14 atoms produced in the upper atmosphere combine with oxygen to yield 14CC>2, which slowly diffuses into the lower atmosphere, where it mixes with ordinary 12CC>2 and is taken up by plants during photosynthesis. When these plants are eaten, carbon-14 enters the food chain and is ultimately distributed evenly throughout all living organisms. 

Photosynthesis annually produces above 50- 109t of oxygen (i.e., an order of 3.3 1014% of its supply in the atmosphere). Hence, we can see that only by means of photosynthesis can the oxygen supplies in the atmosphere be totally renewed during a time period of 300,000 years. About 80% of the total amount of oxygen produced... 

Oxygen is produced during the light period of photosynthesis in the thylakoid membranes of green plant chloroplasts and the internal membranes of bacteria. PSII oxidoreductase oxidizes water, producing molecular oxygen on one side of the membrane ... 

During photosynthesis nutrients, including nitrogen, are assimilated into organic matter and molecular oxygen is produced, depicted schematically by... 

Radioactive isotopes are often used as tracers to follow the path of an element through a chemical reaction. For example, using radiotracers chemists have determined that the oxygen atoms in O2 that are produced by a green plant during photosynthesis come from the oxygen in water and not the oxygen in carbon dioxide. 

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