However, in the form of N2, nitrogen is unusable by all organisms except for a few primitive bacteria that are capable of converting N2 gas to ammonia (NH3). This process of conversion is called nitrogen fixation, and makes the nitrogen available for use by organisms.
1 Simple carbohydrates have very simple chemical structures and are made of small molecules. 2  Complex carbohydrates have very complex structures while the molecules are large, unlike simple carbohydrates.
Generally speaking, simple carbs are digested and absorbed more quickly and easily than complex carbs, according to the NIH. Simple carbohydrates contain just one or two sugars, such as fructose (found in fruits) and galactose (found in milk products).These single sugars are called monosaccharides.enerally speaking, simple carbs are digested and absorbed more quickly and easily than complex carbs, according to the NIH. Simple carbohydrates contain just one or two sugars, such as fructose (found in fruits) and galactose (found in milk products).