A1.1 Water as the Medium for Life

Vocabulary flashcards covering the chemical, physical, and biological properties of water, transport mechanisms, physical properties comparison between air and water, and origin/retention of water.

Polar covalent bond

A covalent bond formed by the unequal sharing of electrons between atoms, resulting in a partial negative charge ($\delta^-$) on the more electronegative atom and a partial positive charge ($\delta^+$) on the less electronegative atom.

Hydrogen bond

A weak force of attraction formed between the partially positive hydrogen atom ($\delta^+$) of one polar molecule and the partially negative atom ($\delta^-$) of an adjacent polar molecule.

Cohesion

The property of like water molecules sticking to each other as a result of hydrogen bonding.

Surface tension

The elastic-like property of a liquid surface that allows it to resist external force, caused by cohesive attraction between surface water molecules pulling inward to minimize surface area.

Adhesion

The attraction between polar water molecules and other polar or charged molecules or surfaces.

Capillary action

The movement of water through narrow spaces or thin channels caused by adhesive forces between water molecules and surrounding polar materials.

Hydrophilic

Describing polar or charged molecules that have an affinity for water and readily dissolve in aqueous solutions.

Hydrophobic

Describing non-polar or uncharged molecules that repel water and are insoluble in aqueous solutions.

Lipoprotein complex

A spherical assembly composed of an outer single layer of phospholipids and proteins enclosing a hydrophobic core of fats and cholesterol, allowing non-polar lipids to be transported in blood plasma.

Buoyancy

The upward vertical force exerted by a fluid on an object immersed in or floating on it, equal to the weight of the fluid displaced by the object.

Viscosity

The measure of a fluid's resistance to flow, caused by internal friction as adjacent parts of the fluid move relative to each other.

Specific heat capacity

The amount of heat energy required to raise the temperature of $1\,\text{g}$ of a substance by $1\,^\circ\text{C}$, which for water is $4.18\,\text{J}\,\text{g}^{-1}\,\text{K}^{-1}$.

Thermal conductivity

The rate at which heat energy passes through a material, which is significantly higher in water than in air.

Latent heat of vaporization

The heat energy required to transform a liquid into a gas, providing a cooling effect on skin as hydrogen bonds break during sweat evaporation.

Goldilocks zone

The habitable orbital distance around a star where temperatures permit water to remain in liquid form on a planet's surface.

Swim bladder

An air-filled internal organ in bony fish used to adjust overall body density and maintain neutral buoyancy at varying depths.

Gas vesicles

Gas-filled protein structures used by photosynthetic cyanobacteria to regulate buoyancy and float near the water surface.

Ringed seal (Pusa hispida)

An aquatic mammal adapted to icy water habitats with a hydrodynamic body and a thick layer of blubber for insulation and buoyancy.

Black-throated loon (Gavia arctica)

An aquatic bird adapted with dense bones to reduce buoyancy for diving and hydrophobic oil-coated plumage to trap insulating air.

Interstitial fluid

The aqueous fluid surrounding and bathing cells in multicellular organisms.

Transpiration

The process of water evaporation from leaf cell walls through stomata, generating tension that pulls a continuous water column up through plant xylem.