Inorganic Nutrients
As we have already looked at, all organisms need a supply of organic nutrients such as glucose and amino acids for growth and reproduction, yet they also need a supply of chemical elements. For this reason, both autotrophs and heterotrophs obtain inorganic nutrients from the abiotic environment. These chemicals are:
Nutrient Cycles |
The supply of inorganic nutrients is maintained by nutrient cycling.
The supplies f chemical elements on our Earth is limited, yet although living organisms have been using them for 3 billion years, they have not run out. This is because through living organisms, these chemicals are endlessly recycled. As was explained above, organisms absorb the elements they need in the form of inorganic nutrients from the abiotic environment, use them and then return the to the environment with their atomic constitution unchanged. Usually, an element has to pass through several living organisms and levels of the food chain before it is returned to the environment. This process is called the nutrient cycle and its details vary from element to element; for example, the carbon cycle (right) is very different from the nitrogen cycle (below). |