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.
Simple carbohydrates are sugars made from atoms of carbon, oxygen, and hydrogen. Inside cells, sugar molecules are broken down. This process provides usable energy for the cell. Simple sugar molecules can also be linked into long chains to form more complex carbohydrates, such as starch, cellulose, and glycogen. Starch and cellulose are complex carbohydrates made by plant cells.