Biomolecules: Properties of Water

A set of vocabulary flashcards detailing the biological relevance, thermal, physical, cohesive, adhesive, and solvent properties of water, along with aquatic organism adaptations.

Cytosol

The liquid component of a cell, predominantly composed of water ($>70\%$), which allows for solutes to be dissolved and able to interact.

Polarity of Water

A slight difference in charge between the poles of a water molecule resulting from unequal electron sharing, where oxygen attracts electrons more strongly to become slightly negative ($\delta-$) and hydrogen becomes slightly positive ($\delta+$).

Hydrogen Bonding

Relatively strong polar associations formed between a slightly positive ($\delta+$) hydrogen dipole and a slightly negative ($\delta-$) oxygen dipole of different water molecules.

Solvent

A substance that dissolves another substance (the solute) to form a solution.

Universal Solvent

A term for water referring to its capacity to dissolve a large number of charged (ions) or polar substances by forming dispersive hydration shells.

Hydrophilic

Describes a substance that is soluble in water ('water-loving').

Hydrophobic

Describes non-polar substances (such as lipids) that do not dissolve in water ('water-hating').

Cohesive Properties

The ability of water molecules to stick together by forming intermolecular hydrogen bonds.

Surface Tension

An inward force at the fluid surface created by hydrogen bonding between internal molecules, giving the surface an elastic tendency.

Adhesive Properties

The ability of water molecules to stick to other molecules with similar polar or ionic properties.

Capillary Action

The flow of water in opposition to gravitational forces when under tension, driven by adhesion to charged or polar surfaces and dependent on pore diameter.

Cellulose

A polar polysaccharide that makes up the cell walls of xylem vessels, allowing water molecules to adhere during transport.

Specific Heat Capacity

The energy required to heat $1\,\text{gram}$ of a substance by $1^\circ\text{C}$.

Heat of Vaporisation

The energy absorbed per gram of a liquid to change state into a gas.

Heat of Fusion

The amount of energy lost when $1\,\text{g}$ of liquid becomes $1\,\text{g}$ of solid at $0^\circ\text{C}$.

Thermal Conductivity

A measure of a medium's ability to move heat across a temperature gradient.

Buoyancy

The upward force applied to an object in a medium, which is determined by the density of the medium.

Viscosity

A measure of a fluid's tendency to flow, influenced in water by intermolecular hydrogen bonding that generates friction.

Thermal Conductivity (Air vs. Water)

Air has low thermal conductivity ($0.024\,\text{WmK}$), whereas water has high thermal conductivity ($0.58\,\text{WmK}$), causing heat to be lost more rapidly in water.

Specific Heat Capacity (Air vs. Water)

Air has low specific heat capacity ($1.005\,\text{J/g}\cdot^\circ\text{C}$), whereas water has high specific heat capacity ($4.186\,\text{J/g}\cdot^\circ\text{C}$), making water temperature harder to change.

Black-Throated Loon (Gavia arc/ca)

An Arctic bird adapted to water's physical properties through solid bones for diving, rear-located legs for propulsion in viscous water, and interlocking feathers to prevent heat loss.

Ringed Seal (Pusa hispida)

An Arctic aquatic mammal adapted to water with dense bones for staying submerged, a streamlined body to move through viscous water, and an outer fur coat with blubber to prevent heat loss.