Cycles of Matter: The Role of Water

This set of vocabulary flashcards covers the hydrologic cycle, the unique chemical properties of water due to hydrogen bonding, and its role in biogeochemical cycles.

Hydrologic cycle

The continuous process by which a finite amount of water is recycled through the biosphere in liquid, solid, and gaseous phases.

Biogeochemical cycles

The pathways through which water and chemical nutrients move through both the biotic and abiotic components of the environment.

Transpiration

The process by which water is absorbed by plant roots and then released into the atmosphere as vapor through leaf pores.

Stomata

Small pores on the surface of plant leaves that facilitate gas exchange and the release of water vapor during transpiration.

Evapotranspiration

The combined volume of water that enters the atmosphere from a land area via transpiration and surface evaporation.

Metabolic water

Water generated within the cells of an organism as a byproduct of the chemical reactions during cellular respiration.

Polar molecule

A molecule, such as water, that has a slightly positive charge at one end and a slightly negative charge at the other due to uneven electron distribution.

Hydrogen bond

A weak attraction between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another molecule.

Universal solvent

A term describing water's ability to dissolve a wide range of substances because of its polar nature and capacity for hydrogen bonding.

Density of water

A physical property where water reaches its maximum value of $1\,kg/L$ at $4\,^\circ\text{C}$, becoming less dense as it freezes into a crystalline structure.

Cohesion

The attraction between water molecules that causes them to stick together, which is responsible for surface tension.

Adhesion

The attraction of water molecules to different substances, such as the internal cell walls of a plant's water-conducting tissues.

Xylem

The water-conducting tissue in plants where adhesion and cohesion allow water to move upward against the force of gravity.

Heat capacity

The amount of heat energy required to change the temperature of a substance; water's high value helps moderate internal and environmental temperatures.

Ecosystem services

The essential benefits provided by natural features, such as freshwater sources, that fulfill human and ecological needs.

Water quality

The standard of water suitability for use, which can be diminished by the presence of pathogens or toxic chemicals.