1. Carbohydrates: These are composed of carbon, hydrogen, and oxygen. They serve as a primary source of energy for living organisms, as well as structural components of cells. Examples include sugars, starches, and cellulose.

2. Lipids: These are mostly composed of carbon and hydrogen, with a smaller proportion of oxygen. Lipids include fats, oils, waxes, and steroids. They function as long-term energy storage, insulation, and components of cell membranes.

3. Proteins: These are large, complex molecules composed of amino acids. They perform a vast array of functions in living organisms, including:

* Enzymes: Catalyze biochemical reactions.

* Structural components: Provide support and shape to cells and tissues.

* Hormones: Act as chemical messengers.

* Antibodies: Help the immune system fight off infections.

4. Nucleic Acids: These are composed of nucleotides, which are made up of a sugar, a phosphate group, and a nitrogenous base. Nucleic acids store and transmit genetic information. The two main types are:

* Deoxyribonucleic acid (DNA): Carries the genetic instructions for the development and functioning of an organism.

* Ribonucleic acid (RNA): Involved in protein synthesis.