Carbon Cycle Steps
The carbon cycle is basically a three step process involving photosynthesis and respiration. Green plants …show more content…
Although we usually think only of breathing oxygen when we hear the word "respiration," it has a broader meaning that involves oxygen. To a biologist, respiration is the process in which oxygen is used to break down organic compounds into carbon dioxide (CO2) and water (H2O). For an animal then, respiration is both taking in oxygen (and releasing carbon dioxide) and oxidizing its food (or burning it with oxygen) in order to release the energy the food contains. In both cases, carbon is returned to the atmosphere as carbon dioxide. Carbon atoms that started out as components of carbon dioxide molecules have passed through the body of living organisms and been returned to the atmosphere, ready to be recycled …show more content…
Nitrifying bacteria like Nitrosomonas convert ammonia to nitrite and another bacterium called
Nitrobacter converts nitrate to nitrate.
Nitrate Assimilation
The nitrate present in the soil is absorbed by plants through the root system in the form of NO3 - ions. But it cannot be used by plants directly. So it is first reduced to nitrite by the enzyme nitrate reductase. Nitrite is then converted to Ammonia by the enzyme nitrite reductase series of steps requiring a total of eight electrons provided by reduced NAD and Ferredoxin (Fd). This reduction of Nitrate to Ammonia and its incorporation into cellular proteins by aerobic micro organisms and higher plants is called Nitrate assimilation.
Denitrification The process of conversion of nitrate and nitrite into ammonia, nitrogen gas and nitrous oxide (N2O) is called denitrification. This process ends in the release of gaseous nitrogen into the atmosphere and thus completes the nitrogen cycle. A number of bacteria such as Pseudomonas denitrificans, Bacillus subtilis and Thiobacillus dentrificans are involved in this