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.
Carbohydrates: Complex Carbs vs Simple Carbs. Carbohydrates are the main source of calories in a healthy diet and are the primary fuel for the brain and muscles. Typically, about three-fourths of daily calories should come from carbohydrates. It's also important to choose the best carbohydrate sources. That means two things: 1  Choose complex carbohydrates, rather than simple carbohydrates. 2  Choose carbohydrates that still have their fiber, like brown rice or brown bread, rather than white rice or white bread, from which the fiber has been stripped away.