It's not quite accurate to say there are only 6 elements most important in biology. While those 6 are incredibly crucial, many others play vital roles. However, the 6 most abundant elements in living organisms are:

1. Oxygen (O): Makes up a large portion of water, the essential solvent in cells. It's also found in carbohydrates, lipids, proteins, and nucleic acids.

2. Carbon (C): The backbone of all organic molecules, including carbohydrates, lipids, proteins, and nucleic acids.

3. Hydrogen (H): Found in water, carbohydrates, lipids, proteins, and nucleic acids. It's also involved in many chemical reactions.

4. Nitrogen (N): A major component of proteins and nucleic acids (DNA and RNA).

5. Calcium (Ca): Involved in bone and teeth formation, muscle contraction, nerve impulse transmission, and blood clotting.

6. Phosphorus (P): Found in nucleic acids, phospholipids (cell membranes), and ATP (energy currency of the cell).

It's important to remember that these are just the most abundant elements. Many other elements are crucial for life, even in small amounts, such as potassium, sulfur, sodium, chlorine, magnesium, iron, and more.