Anatomy and Physiology II Practice Test

Which process involves the absorption of heat through the transformation of water from liquid to vapor?

1. Evaporation

2. Condensation

3. Transpiration

4. Perspiration

The correct answer is: Evaporation

The process that involves the absorption of heat through the transformation of water from liquid to vapor is known as evaporation. During evaporation, molecules at the surface of the liquid water gain enough energy to overcome intermolecular forces and enter the gaseous state. This transition requires energy, which is supplied in the form of heat from the surrounding environment. Consequently, evaporation has a cooling effect on the surface from which the liquid is evaporating, as the remaining liquid loses some of its thermal energy. In contrast, condensation refers to the process where vapor transitions into liquid water, releasing heat into the environment rather than absorbing it. Transpiration occurs in plants, where water moves from the soil through the plant and evaporates from the surface of leaves, which also involves heat absorption but is specific to biological processes. Perspiration, or sweating in humans, involves the secretion of sweat onto the skin, where it then evaporates, providing a cooling effect, but it is a physiological response rather than a direct process of water transformation.