IB Biology: Water Properties and Aquatic Habitats

Vocabulary flashcards reviewing the chemical structure, hydrogen bonding, cohesive/adhesive, solvent, physical properties of water, aquatic adaptations, and extraplanetary origin.

Medium for Life

The liquid environment (water) in which the first cells originated and where most essential metabolic processes of life occur.

Polar Covalent Bond in Water

A covalent bond formed by unequal electron sharing between oxygen and hydrogen atoms, caused by oxygen's larger nucleus ($8$ protons) attracting shared electrons more strongly than hydrogen's nucleus ($1$ proton).

Dipolarity

The charge imbalance in a water molecule resulting in a partial negative charge ($\text{δ}^-$) near the oxygen atom and partial positive charges ($\text{δ}^+$) near the hydrogen atoms.

Hydrogen Bond

A weak intermolecular attraction formed between the partially positive ($\text{δ}^+$) hydrogen atom of one polar molecule and the partially negative ($\text{δ}^-$) oxygen atom of an adjacent water molecule.

Cohesion

The property of water molecules sticking together due to intermolecular hydrogen bonding in a tetrahedral arrangement.

Surface Tension

The tendency of liquid surfaces to shrink into the smallest surface area possible, caused by net inward cohesive forces between water molecules at the surface.

Adhesion

The attraction between polar water molecules and other polar or charged surfaces, enabling hydrogen bonds to form with materials such as glass, cellulose, and cell walls.

Capillary Action

The movement of water through narrow tubes or porous materials against gravity, driven by adhesive forces to polar surfaces and cohesive forces between water molecules.

Transpiration Stream

The continuous upward movement of water from roots through xylem vessels to leaves in plants, powered by leaf transpiration and sustained by cohesive and adhesive forces.

Universal Solvent

A property of water resulting from its polarity, allowing it to dissolve polar and ionic solutes by weakening electrostatic forces and forming hydration shells around ions.

Hydrophilic

Describing polar or charged substances ('water-loving') that readily associate with and dissolve in water, such as glucose, cellulose, amino acids with polar side chains, and ionic salts.

Hydrophobic

Describing non-polar, uncharged substances ('water-hating') that do not dissolve in or mix with water, such as lipids, fatty acids, cholesterol, and oxygen gas.

Lipoprotein Complex

A spherical transport particle composed of a phospholipid monolayer and embedded proteins surrounding a non-polar core, used to transport insoluble fats and cholesterol through blood plasma.

Buoyancy

The vertical upward force exerted by a fluid on an object placed in or on it; water's high density ($1000\text{ kg/m}^3$) provides significant buoyant support compared to air ($1.204\text{ kg/m}^3$).

Viscosity

A fluid's resistance to flow caused by internal friction; water has a higher viscosity ($50 \times$ more viscous than air) due to hydrogen bonding and dissolved solutes.

Thermal Conductivity

The rate at which heat energy passes through a material across a temperature gradient; water transfers heat much faster ($0.58\text{ W/m}\text{K}$) than air ($0.024\text{ W/m}\text{K}$).

Specific Heat Capacity

The amount of energy required to raise the temperature of $1\text{ g}$ of a substance by $1^\text{o}\text{C}$; water has a high value of 4.186\text{ J/g}\text{^\text{o}C} because hydrogen bonds restrict molecular motion.

Latent Heat of Vaporization

The large amount of heat energy absorbed to break hydrogen bonds and turn liquid water into gas, providing an effective evaporative cooling mechanism such as sweating.

Ringed Seal (Pusa hispida)

An Arctic marine mammal adapted to water's physical properties via a streamlined body shape for viscosity, a thick blubber layer and outer fur coat for thermal insulation, and denser bones for submersion.

Black-Throated Loon (Gavia arctica)

An aquatic bird adapted to air and water environments, featuring solid yet lightweight bones to balance flight and submersion buoyancy, rear-located legs for water propulsion, and interlocking feathers to restrict heat loss.

Extraplanetary Origin of Water

The hypothesis that Earth's water originated from impacts with water-rich asteroids containing hydrated minerals during the first few hundred million years of Earth's history.

Goldilocks Zone (Habitable Zone)

The region around a star where planet surface temperatures allow water to condense into liquid form and remain retained due to sufficient gravity and moderate temperatures.