Water and Life - Vocabulary Flashcards (Lecture Notes)

Vocabulary-style flashcards covering key terms related to water’s role in life and astrobiology.

Water as a solvent

Water dissolves many solutes by forming hydration shells and hydrogen bonds, enabling transport and metabolic reactions.

Hydration shell

A surrounding cluster of water molecules that stabilizes a dissolved solute.

Solvation

Interaction of a solvent with a dissolved solute during dissolution.

Hydrophilic

Molecules that are attracted to water and can form hydrogen bonds with it.

Hydrophobic

Nonpolar molecules that do not attract water and tend to cluster in water.

Polar covalent bond

A bond where electrons are shared unequally, creating partial charges on atoms.

Nonpolar covalent bond

A bond where electrons are shared equally, producing no significant charge separation.

Ionic bond

An attraction between oppositely charged ions formed by transfer of electrons.

Hydrogen bond

A weak intermolecular attraction between a partly positive hydrogen and a more electronegative atom on another molecule.

Cohesion

Water molecules sticking to each other via hydrogen bonds, contributing to surface tension and transport in organisms.

Adhesion

Water molecules sticking to polar or charged surfaces, enabling capillary movement through narrow spaces.

Surface tension

The inward cohesive force at the surface of a liquid that makes it behave as if covered by a membrane.

Capillary action

Movement of water in narrow tubes due to adhesion to surfaces and cohesion within water.

Xylem

Plant vascular tissue that transports water from roots to leaves through continuous tubes.

Osmosis

Diffusion of water across a selectively permeable membrane from higher to lower water potential.

Metabolism

All biochemical reactions in cells; water acts as a reactant or product in many steps.

Condensation reaction

Reaction where two molecules join and water is produced as a product.

Hydrolysis reaction

Reaction where water is used to break bonds, producing smaller molecules.

Specific heat capacity

Energy required to raise 1 kg of a substance by 1 Kelvin; water has a very high value, stabilizing temperatures.

Thermal conductivity

Ability of a material to transfer heat; water conducts heat, influencing heat transfer in organisms.

Viscosity

Resistance to flow; water’s hydrogen bonding increases viscosity relative to gases.

Buoyancy

Upward force on submerged objects; depends on the density of the object relative to the surrounding fluid.

Density

Mass per unit volume; determines buoyancy and transport behavior.

D/H ratio

Deuterium-to-hydrogen ratio used to trace the origin of water in the Solar System.

Extraterrestrial origin of water

Water delivered to early Earth by asteroids and comets, rather than forming in situ.

Goldilocks zone

Habitable zone around a star where conditions allow liquid water on a planet’s surface.

Astrobiology

Study of the origins, distribution, and possibility of life in the universe.

RNA World

Hypothetical early stage in which RNA carried genetic information and acted as a catalyst.

Prebiotic chemistry

Chemistry that leads to the formation of biologically relevant molecules before life begins.

Enceladus plumes

Geyser-like plumes on Saturn’s moon Enceladus indicating subsurface liquid water and potential habitability.