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.
â¢ Starch is a complex carbohydrate, whereas sugar is a simple carbohydrate. â¢ Starch is made up of long chains of simple sugar called glucose, whereas sugar can be made up of either a single sugar molecule or two simple sugar molecules linking together by a glycosidic bond.tarch vs Sugar. Starch and sugars are two types of carbohydrates found in food. Carbohydrates are the organic compounds, made up of carbon (c), hydrogen (H), and oxygen (O) in the ratio of one oxygen atom and two hydrogen atoms for every one carbon atom (CH 2 O).