Biology and Scientific Research Practice Test 2025 – Your All-in-One Guide to Exam Success!

Cohesion refers to the attraction between molecules of the same substance, which is a fundamental concept in biology and chemistry. This property arises due to intermolecular forces, such as hydrogen bonds in water, causing molecules to stick together. Cohesion is responsible for several important phenomena, including the ability of water to form droplets, the movement of water through plant veins, and its high surface tension.

The other terms describe different interactions. Adhesion refers to the attraction between molecules of different substances, which allows materials like water to spread on surfaces. Surface tension describes the elastic-like force at the surface of liquids caused by cohesive forces, which allows some objects to float on a liquid's surface, despite being denser than the liquid. Capillarity, or capillary action, is the phenomenon where liquid rises or falls in a narrow space against gravity, resulting from both cohesion and adhesion interacting in the context of narrow tubes or porous materials. Thus, cohesion specifically focuses on the molecular attraction within the same substance.