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.
What are they? Complex Carbohydrates are one of the two types of carbohydrates, the other being simple carbohydrates. Alternatively known as polysaccharides, complex carbohydrates are composed of a long as well as a complex chain of sugar or glucose molecules.