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.
Categories. Digestible carbohydrate includes simple and complex carbohydrates. Simple types may be single sugars, or monosaccharides, and double sugars, or disaccharides, while complex carbohydrates include starches, which are larger molecules.ategories. Digestible carbohydrate includes simple and complex carbohydrates. Simple types may be single sugars, or monosaccharides, and double sugars, or disaccharides, while complex carbohydrates include starches, which are larger molecules.