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Water and Life - General Biology

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  • What type of bond forms between water molecules?
    Hydrogen bonds form between the polar covalent bonds of water molecules.
  • Name four emergent properties of water that contribute to Earth's suitability for life.
    Cohesive behavior, ability to moderate temperature, expansion upon freezing, and versatility as a solvent.
  • What is cohesion in water molecules?
    Cohesion is the attraction between water molecules due to hydrogen bonding, resulting in high surface tension.
  • How does adhesion help plants transport water?
    Adhesion is the attraction between water and plant cell walls, helping water move upward against gravity.
  • How does water moderate temperature?
    Water absorbs heat from warmer air and releases heat to cooler air, changing temperature only slightly.
  • Define thermal energy and temperature.
    Thermal energy is the total kinetic energy of molecules; temperature is the average kinetic energy.
  • What is a calorie in terms of water heating?
    A calorie is the heat needed to raise 1 g of water by 1°C or released when it cools by 1°C.
  • What is specific heat and why is water's specific heat high?
    Specific heat is heat needed to change 1 g of substance by 1°C; water's is high due to hydrogen bonding.
  • Explain evaporative cooling in water.
    Evaporation removes heat from the surface, cooling the remaining liquid, stabilizing temperatures.
  • Why does ice float on liquid water?
    Ice is less dense because hydrogen bonds form a crystalline lattice that spaces molecules farther apart.
  • What is a solution, solvent, and solute?
    A solution is a homogeneous mixture; solvent dissolves the solute, which is the dissolved substance.
  • Why is water called a versatile solvent?
    Water's polarity allows it to dissolve ionic compounds and polar molecules by forming hydration shells.
  • Define hydrophilic and hydrophobic substances.
    Hydrophilic substances attract water; hydrophobic substances repel water, often nonpolar like oils.
  • What is the significance of water in the search for life on other planets?
    Water is essential for life; planets with water, like Mars, are prime targets in the search for life.
  • What happens during the dissociation of water molecules?
    Water molecules split into hydronium ions (H3O+) and hydroxide ions (OH-).
  • How do acids and bases affect hydrogen ion concentration?
    Acids increase H+ concentration; bases reduce H+ concentration in a solution.
  • What is the pH scale and what does it measure?
    The pH scale measures H+ concentration; values below 7 are acidic, above 7 are basic.
  • What role do buffers play in biological systems?
    Buffers minimize pH changes by reversibly combining with H+ and OH- ions.
  • How does ocean acidification occur?
    CO2 dissolves in seawater forming carbonic acid, lowering pH and affecting marine life.
  • Why is carbonate ion important for marine organisms?
    Carbonate ions are needed for calcification to build calcium carbonate structures like coral reefs.