1. Carbohydrates: These are the primary energy source for living organisms. They are composed of carbon, hydrogen, and oxygen. Examples include sugars, starches, and cellulose.

2. Lipids: These are fats, oils, and waxes that provide long-term energy storage, insulation, and protection. They are composed of carbon, hydrogen, and oxygen, but with a higher proportion of hydrogen compared to carbohydrates.

3. Proteins: These are complex molecules that perform a wide variety of functions in living organisms, including structural support, enzymatic activity, transport, and defense. They are composed of amino acids, which contain carbon, hydrogen, oxygen, and nitrogen.

4. Nucleic Acids: These are responsible for storing and transmitting genetic information. They are composed of nucleotides, which are made up of a sugar, a phosphate group, and a nitrogenous base. The two main types of nucleic acids are DNA (deoxyribonucleic acid) and RNA (ribonucleic acid).