Questions: 2. What element is the building block for most biological molecules? What makes it so versatile?

The element that is the building block for most biological molecules is carbon.

Carbon is incredibly versatile for several reasons:

1. Tetravalency: Carbon has four valence electrons, allowing it to form four covalent bonds with other atoms. This property enables carbon to form a wide variety of complex molecules with different shapes and sizes.

2. Catenation: Carbon atoms can bond with each other to form long chains, branched structures, and rings. This ability to form stable, long chains and complex structures is unique and essential for the diversity of organic molecules.

3. Bonding with Various Elements: Carbon can form stable bonds with many other elements, including hydrogen, oxygen, nitrogen, sulfur, and phosphorus. This allows for the formation of a wide range of functional groups and compounds, which are crucial for the structure and function of biological molecules.

4. Multiple Bonding: Carbon can form single, double, and triple bonds with other atoms, adding to the diversity of structures it can create. This ability to form multiple types of bonds contributes to the complexity and functionality of organic molecules.

In summary, carbon's ability to form four covalent bonds, bond with itself to create complex structures, and bond with a variety of other elements makes it the fundamental building block of most biological molecules.