Campbell Biology Practice Test 2026 - Free Biology Practice Questions and Study Guide

The correct answer is hydrogen bond, which is formed through an electrostatic attraction between a proton, typically from a hydrogen atom, and an electronegative atom such as oxygen, nitrogen, or fluorine. This type of bond is weaker than covalent and ionic bonds and arises when hydrogen is covalently bonded to an electronegative atom, creating a partial positive charge on the hydrogen that can attract other electronegative atoms nearby.

In terms of the other options, covalent bonds involve the sharing of electrons between atoms, leading to strong interactions without the specific electrostatic attraction characteristic of hydrogen bonds. Ionic bonds, on the other hand, result from the transfer of electrons and the attraction between positively and negatively charged ions, rather than the specific attraction between a hydrogen proton and an electronegative atom. Metallic bonds describe a different phenomenon where metal atoms share a pool of electrons, allowing for conductivity and malleability, but do not involve the same type of electrostatic interaction seen in hydrogen bonds. Thus, the unique nature of hydrogen bonds stems from the specific pairing of hydrogen with electronegative atoms, making it the most fitting answer to the question.