Carbon dioxide aerobic fungi and bacteria. In vertebrates, the carbon dioxide travels in the blood from the body's tissues to the skin (e.g., amphibians) or the gills (e.g., fish), from where it dissolves in the water, or to the lungs from where it is exhaled. During active photosynthesis, plants can absorb more carbon dioxide from the atmosphere than they release in respiration. Carbon fixation is a biochemical process by which atmospheric carbon dioxide is incorporated by plants, algae and (cyanobacteria) into energy-rich organic molecules such as glucose, thus creating their own food by photosynthesis. Photosynthesis uses carbon dioxide and water to produce
Carbon dioxide standard hydrogen electrode. The nickel-containing enzyme carbon monoxide dehydrogenase catalyses this process. Carbon dioxide is colorless. At low concentrations the gas is odorless; however, at sufficiently-high concentrations, it has a sharp, acidic odor. At standard temperature and pressure, the density of carbon dioxide is around 1.98 kg/m, about 1.67 times that of air. Carbon dioxide has no liquid state at pressures below . At 1 atmosphere (near mean sea level pressure), the gas deposits directly to a solid at temperatures below and the solid sublimes directly to a gas above −78.5 °C. In its solid state, carbon dioxide is commonly