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 are often used as building blocks of larger, complex carbohydrates. 2  The empirical structure of simple carbohydrate is C 6 H 12 O 6 or (CH 2 O) 6 while that of complex carbohydrate is (C 6 H 10 O 5) n, in which ânâ is the number of monomer units.
Cellulose forms the structures that give plants their shape, and it's the main component of dietary fiber. Vegetables such as green beans, broccoli, and spinach contain less starch, but they have more cellulose. The difference between complex carbohydrates and simple carbohydrates is just the size of the molecules. Simple carbohydrates are made up of only one or two sugar units, whereas complex carbs contain at least three sugars.