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.
What makes one carbohydrate different from another is the number of sugar units it contains and how the units are linked together. 1  Simple carbohydrates: These carbohydrates have only one or two units of sugar. A carbohydrate with one unit of sugar is called a simple sugar or a monosaccharide (mono = one; saccharide = sugar). Fructose (fruit sugar) is a monosaccharide, and so are glucose (blood sugar), the sugar produced when you digest carbohydrates, and galactose, the sugar derived from digesting lactose (milk sugar). A carbohydrate with two units of sugar is called a double sugar or a disaccharide (di = two). Sucrose (table sugar), which is made of one unit of fructose and one unit of glucose, is a disaccharide. Complex carbohydrates: Also known as polysaccharides (poly = many), these carbs have more than two units of sugar linked together.