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Carbon on Earth naturally occurs in two stable isotopes, with 98.9% in the form of 12 C and 1.1% in 13 C. [1] [8] The ratio between these isotopes varies in biological organisms due to metabolic processes that selectively use one carbon isotope over the other, or "fractionate" carbon through kinetic or thermodynamic effects. [1]
Cyanobacteria such as these carry out photosynthesis. Their emergence foreshadowed the evolution of many photosynthetic plants and oxygenated Earth's atmosphere. Biological carbon fixation, or сarbon assimilation, is the process by which living organisms convert inorganic carbon (particularly carbon dioxide, CO 2) to organic compounds.
Photosynthetic capacity is limited by carboxylation capacity and electron transport capacity. For example, in high carbon dioxide concentrations or in low light, the plant is not able to regenerate ribulose-1,5-bisphosphate fast enough (also known RUBP, the acceptor molecule in photosynthetic carbon reduction).
Many plants lose much of the remaining energy on growing roots. Most crop plants store ~0.25% to 0.5% of the sunlight in the product (corn kernels, potato starch, etc.). Photosynthesis increases linearly with light intensity at low intensity, but at higher intensity this is no longer the case (see Photosynthesis-irradiance curve). Above about ...
The CO 2 compensation point (Γ) is the CO 2 concentration at which the rate of photosynthesis exactly matches the rate of respiration. There is a significant difference in Γ between C 3 plants and C 4 plants: on land, the typical value for Γ in a C 3 plant ranges from 40–100 μmol/mol, while in C 4 plants the values are lower at 3–10 μmol/mol. Plants with a weaker CCM, such as C2 ...
When the concentration decreases past a certain point a timer is started, and is stopped as the concentration passes at a second point. The difference between these concentrations gives the change in carbon dioxide in ppm. [6] Net photosynthetic rate in micro grams carbon dioxide s −1 is given by; (V • p • 0.5 • FSD • 99.7) / t [6]
These include the amount of light available, the amount of leaf area a plant has to capture light (shading by other plants is a major limitation of photosynthesis), the rate at which carbon dioxide can be supplied to the chloroplasts to support photosynthesis, the availability of water, and the availability of suitable temperatures for carrying ...
Calvin–Benson cycle. C 3 carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, the other two being C 4 and CAM.This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of 3-phosphoglycerate through the following reaction: