Water and Electrolytes Quiz

Water and Electrolytes

• Water is the most abundant substance in living systems, making up at least 70% of their weight.
• The properties of water have shaped the course of evolution.

Role of Water in Biological Processes

• Water transports nutrients and oxygen into cells.
• It regulates body temperature.
• Water is a universal solvent, meaning it dissolves many substances.
• Metabolic reactions occur in water.
• Water is a structural component of macromolecules.

Structure of Water

• Water has a tetrahedral geometry.
• Water is an electric dipole.
• Oxygen attracts electrons more strongly than hydrogen.
• Oxygen has a slightly negative charge, and hydrogens have slightly positive charges.
• These charges create a dipole moment.
• Oxygen's electronegativity is greater than hydrogen's.

Covalent Bond

• Two nonmetal atoms share electrons in a covalent bond.
• Oxygen atoms share electrons to create a nonpolar oxygen molecule.
• In water, the shared electrons are unequally distributed, resulting in a polar covalent bond.

Hydrogen Bond

• A hydrogen bond forms when a hydrogen atom from one molecule attracts an electronegative atom from another molecule.
• Hydrogen bonds are electrostatic attractions.
• These bonds are weak, but they are strong when many are formed.
• Hydrogen bonds are directional.

Structure of Water-Hydrogen Bonds

• Electrostatic attraction exists between oxygen and hydrogen in different water molecules.
• Hydrogen bonds are weak and short-lived.
• Bonds are strongest when molecules are oriented to maximize electrostatic interaction (straight line).

Structure of Water-Stages of Water

• Water exists in three states: gaseous (water vapor), liquid, and solid (ice).
• Different states have different structures.
• In gaseous phase, water molecules are far apart and have weak hydrogen bonds.
• Liquid phase involves flickering clusters of water molecules with continuous motion interacting through hydrogen bonds.
• Solid phase has regular crystal lattice structure with four hydrogen bonds per water molecule. Due to this arrangement, ice is less dense than liquid water.

Properties of Water

• Water's polarity allows it to dissolve many substances.
• High heat capacity means it can absorb significant heat without a large temperature change.
• High heat of vaporization is needed for water to evaporate.
• High thermal conductivity.
• Highest density at 4°C.
• Water molecules have high cohesive and adhesive properties, which cause high surface tension.
• Water is a universal solvent.

Universal Solvent

• Water's ability to dissolve substances depends on: Hydrogen bonding with polar groups in non-ionic molecules; high dielectric constant for dissolving ionic compounds; formation of micelles when amphipathic molecules are dissolved in water.
• Hydrophilic compounds dissolve readily in water.
• Hydrophobic compounds do not dissolve in water.
• Amphipathic molecules have both polar and nonpolar regions

Properties of Water- Composition of Body Fluids

• Body fluids contain different concentrations of electrolytes (e.g., sodium, potassium, chloride, bicarbonate).
• The composition of intracellular and extracellular fluids varies.

Properties of Water- Molecular Mobility → Osmotic Effect

• Water movement across membranes depends on solute concentration differences.
• Osmosis is the movement of water across a semipermeable membrane from a less concentrated to a more concentrated solution.

Properties of Water - Osmotic Effect in Biological Systems

• Isotonic solutions have the same concentration of solutes as cells' cytoplasm, causing no net water movement.
• Hypertonic solutions have higher solute concentrations, causing water to move out of cells and shrink them.
• Hypotonic solutions have lower solute concentrations, causing water to move into cells and swell them (potentially bursting).

Osmotic Effect- Alterations in Body Fluid Concentrations

• Dehydration occurs when fluid loss exceeds intake, leading to lower fluid volume.
• Edema occurs due to excessive fluid retention, resulting in swelling.

Test your knowledge on the vital roles of water and electrolytes in biological systems. Explore the properties of water, its structure, and its importance in metabolic processes. This quiz covers fundamental concepts essential for understanding biology.