The Importance of Water in Biological Systems

These flashcards cover the key concepts regarding water's role in biological systems, its properties, and its molecular structure.

Abogenesis

The theory describing how life originated in liquid water through chemical evolution. Water’s role in life origins.

Water's % of the body

Takes up 50 - 70 % of total body weight in all organisms. Water is the most abundant molecule in living systems.

Temperature Regulation (water functions)

Maintains stable body temperature.

Tissue Moisture (water functions)

Keeps mouth, eyes, and nose tissues moist.

Joint Protection (water functions)

Lubricates joints to prevent damage.

Organ Protection (water functions)

Cushions organs and tissues from impact.

Digestion (water functions)

Helps prevent constipation and aids in digestion.

Water Functions

Digestion, Organ Protection, Joint Protection, Tissue Moisture, Temperature Regulation, Nutrient Transport, and Waste Removal.

Cohesion

The property of water molecules sticking to each other via hydrogen bonds.

Adhesion

The property of water molecules sticking to other polar surfaces.

Specific Heat

The amount of heat required to change the temperature of a substance; water has a high specific heat.

Hydrogen Bonds

Weak attractions that form between the δ+ hydrogen of one water molecule and the δ- oxygen of another. A water molecule can form up to 4 hydrogen bonds.

Polar Covalent Bonds

Forms when atoms do not equally share electrons. Oxygen molecules have a greater electronegativity that pulls shared electrons closer and creates a partial (-) charge on the oxygen and partial (+) on the hydrogens.

Polar Molecule

A molecule with a partial positive charge on one end and a partial negative charge on the other, like water.

Water's Molecular Structure

One oxygen atom covalently bonded to two hydrogen atoms. Has a “bent” structure.

Spheres of Hydration

The shells of water molecules that form around dissolved ions.

Transpiration

The process by which water evaporates from plant leaves, creating a pull that moves water from roots to leaves.

Surface Tension Forces

The cohesive force at the water-air interface that allows water molecules to cling to each other and resist external forces.

Ice Density Paradox

The phenomenon where ice is less dense than liquid water, allowing it to float.

Universal Solvent

Water's ability to dissolve many ionic and polar substances due to its polar nature.

Waste Removal (water function)

The process by which water flushes waste products from the body through urine and bowel movements.

Nutrient Transport (water functions)

Water's function in carrying nutrients and oxygen to cells.

Molecular Arrangement in Ice

Molecules are held tightly in a rigid structure, resulting in increased spacing and lower density compared to liquid water.

Hydrogen Bond Activity (Properties)

Bonds are constantly breaking and reforming.

Hydrogen Bond Activity (Ice)

Bonds are stable and locked in place.

Molecular Arrangement (Liquid)

Molecules are random and close-packed.

Density (Liquid)

More dense than Ice (1gram/cm³).

Density (Ice)

Less dense than liquid (0.92gram/cm³).

Space between Molecules (Liquid)

The space between molecules is minimal.

Space between Molecules (Ice)

The space between molecules is larger.

Energy State (Liquid)

Molecules have a higher kinetic energy.

Liquid State Temperature Range (Water Supporting Properties)

The liquid state of water has a temperature range of 0-100 degrees.

Attractive Forces (Surface Tension)

The forces between the water molecules and the surface molecules.

Properties of Hydrophobic Surfaces

Water molecules are less attracted to the surface and creates a stronger surface tension force. The contact angle is 90 degrees.

Properties of Hydrophilic Surfaces

Water molecules are more attracted to the surface and hydrogen bonding allows the water molecules to spread evenly.

High Heat Capacity (Water Temperature Regulation)

Water has a very high heat capacity and holds heat effectively. Temperature changes occur slowly.

Temperature Stability (Biological Implication of Water Temp. Regulation)

Protects organisms from rapid temperature changes.

High Body Water Content (Biological Implication of Water Temp. Regulation)

Resists body temperature fluctuations.

Blood Circulation (Biological Implication of Water Temp. Regulation)

Distributes heat throughout the body.

Evaporate Cooling (Biological Implication of Water Temp. Regulation)

Removes heat through sweat.