Biology Chapter on Water Properties
46 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What percentage of the human body is approximately made up of water?

  • 50–60 percent
  • 40–50 percent
  • 70–80 percent
  • 60–70 percent (correct)

    • Which property of water is primarily responsible for its ability to form hydrogen bonds?

  • Dissociation into ions
  • Hydrophobic interactions
  • High heat capacity
  • Polarity of the molecule (correct)

    • What term is used to describe substances that do not interact well with water?

  • Polar
  • Ionic
  • Hydrophobic (correct)
  • Hydrophilic

    • What is the significance of water's high heat capacity?

    <p>It stabilizes temperatures in organisms.</p> Signup and view all the answers

    Why is water termed a unique substance essential for life?

    <p>It exhibits properties like high heat capacity and polarity.</p> Signup and view all the answers

    How does water's polarity contribute to its solvent capabilities?

    <p>By allowing it to form hydrogen bonds with polar substances.</p> Signup and view all the answers

    What process in water leads to the generation of pH?

    <p>Dissociation into ions</p> Signup and view all the answers

    What is the effects of water's adhesive properties in biological systems?

    <p>Governs the movement of water in tree trunks.</p> Signup and view all the answers

    What characterizes strong acids compared to weak acids?

    <p>Strong acids rapidly donate hydrogen ions.</p> Signup and view all the answers

    Which statement about the pH scale is accurate?

    <p>A pH of 7 is neutral.</p> Signup and view all the answers

    How do buffers maintain pH in the body?

    <p>By absorbing excess hydrogen ions or hydroxide ions.</p> Signup and view all the answers

    Why is the replacement of stomach cells critical?

    <p>Stomach acid digests old cells.</p> Signup and view all the answers

    What is the role of bicarbonate ions in blood pH regulation?

    <p>They convert to carbon dioxide when pH is too low.</p> Signup and view all the answers

    Which of the following substances is considered a weak base?

    <p>Seawater</p> Signup and view all the answers

    What occurs when strong bases are introduced to a solution?

    <p>They increase OH– concentrations.</p> Signup and view all the answers

    Why is maintaining a near-neutral pH important for organisms?

    <p>It supports enzyme activities and cellular functions.</p> Signup and view all the answers

    How do antacids function similarly to blood buffers?

    <p>They absorb excess hydrogen ions to moderate pH.</p> Signup and view all the answers

    In terms of pH, what environment is considered inhospitable to life?

    <p>Deviations from pH 7.0 in either direction.</p> Signup and view all the answers

    What characteristic of water allows it to have a lower density in its solid form compared to its liquid form?

    <p>Formation of hydrogen bonds</p> Signup and view all the answers

    Which process involves the escape of water molecules from liquid to gas at temperatures below boiling point?

    <p>Evaporation</p> Signup and view all the answers

    What is a consequence of ice floating on water for aquatic ecosystems?

    <p>Provides an insulating layer to protect organisms</p> Signup and view all the answers

    Why does water require a considerable amount of heat to boil?

    <p>Because of strong hydrogen bonds</p> Signup and view all the answers

    What forms around ionic compounds when they dissolve in water?

    <p>Hydration shell</p> Signup and view all the answers

    What is the critical factor that causes the breaking of hydrogen bonds in water during boiling?

    <p>Increase in kinetic energy</p> Signup and view all the answers

    How does the hydrogen bonding in water contribute to its role as a heat sink?

    <p>It requires more energy to change state.</p> Signup and view all the answers

    What phenomenon occurs when water molecules slide past each other in liquid form?

    <p>Hydrogen bonding</p> Signup and view all the answers

    What happens to cellular membranes when ice forms inside them?

    <p>They rupture due to expansion.</p> Signup and view all the answers

    What is the primary reason that ice floats on liquid water?

    <p>Ice's crystalline structure is less dense.</p> Signup and view all the answers

    Why is water considered a good solvent for ionic compounds?

    <p>It can form hydrogen bonds with charged particles.</p> Signup and view all the answers

    What energy transformation occurs when water evaporates?

    <p>Heat is absorbed from the surroundings.</p> Signup and view all the answers

    Which of the following statements about water’s states is true?

    <p>Ice has a lattice structure that creates space between molecules.</p> Signup and view all the answers

    What is the heat of vaporization for water?

    <p>586 calories per gram</p> Signup and view all the answers

    What phenomenon allows small insects, like water striders, to stay afloat on the surface of the water?

    <p>Surface tension</p> Signup and view all the answers

    Which of the following best explains why plants can transport water from roots to leaves?

    <p>Cohesion creating a pull on the water column</p> Signup and view all the answers

    What happens to the pH of a solution when an acid is dissolved in water?

    <p>The pH decreases because of increased hydrogen ions.</p> Signup and view all the answers

    In the context of pH, what does a lower pH number indicate?

    <p>A higher concentration of hydronium ions</p> Signup and view all the answers

    What is the primary composition of pure water when it ionizes?

    <p>Equal concentrations of H+ and OH- ions</p> Signup and view all the answers

    What is the reason for placing a small scrap of paper on a water droplet allowing it to float?

    <p>Cohesion and surface tension resist the weight of the paper.</p> Signup and view all the answers

    Which of the following best describes capillary action?

    <p>The ability of water to rise in narrow spaces against gravity</p> Signup and view all the answers

    What is the significance of the pH of 7.0?

    <p>It signifies a neutral solution.</p> Signup and view all the answers

    How many moles of H+ ions are produced in pure water per liter at neutral pH?

    <p>1 × 10^-7 moles</p> Signup and view all the answers

    Which force is primarily responsible for keeping water droplets spherical on a surface?

    <p>Cohesion among water molecules</p> Signup and view all the answers

    What type of bonding typically occurs between water molecules due to cohesion?

    <p>Hydrogen bonding</p> Signup and view all the answers

    Which statement about bases is accurate?

    <p>Bases provide hydroxide ions or other ions that react with H+ ions.</p> Signup and view all the answers

    Why is adhesion stronger than cohesion in a thin glass tube when water is present?

    <p>Water molecules are attracted more to the glass than to each other.</p> Signup and view all the answers

    What does the negative logarithm measure in relation to pH?

    <p>The concentration of hydrogen ions</p> Signup and view all the answers

    Study Notes

    Importance of Water for Life

    • Water is essential for life as we know it, comprising 60-70% of the human body.
    • Its unique properties, arising from polarity and hydrogen bonding, are crucial to biological processes.
    • Life originated in a watery environment, and most cellular functions occur in the watery cytoplasm.

    Water's Polarity

    • Water molecules (H₂O) have polar covalent bonds, creating slightly positive hydrogen and slightly negative oxygen regions.
    • This polarity allows water to form hydrogen bonds with other water molecules and polar substances.
    • Hydrophilic substances readily dissolve in water, while hydrophobic substances, like oils, do not.

    Water's States: Gas, Liquid, and Solid

    • Hydrogen bonds constantly form and break in liquid water, influenced by temperature.
    • Increased heat breaks hydrogen bonds, allowing water to become a gas (evaporation).
    • Decreased temperature creates a crystalline solid structure (ice), with hydrogen bonds maintaining spacing, making it less dense than liquid water.
    • This phenomenon allows ice to float, providing insulation for aquatic life. Freezing damages cells due to ice crystal expansion.

    Water's Heat of Vaporization

    • Water has a high heat capacity and heat of vaporization (586 cal/g).
    • This is due to the strong hydrogen bonding that requires substantial energy to separate water molecules.
    • Evaporation cools the environment, vital for temperature regulation in living organisms like humans (sweating).

    Water's Solvent Properties

    • Water's polarity allows it to dissolve many ionic and polar substances.
    • Water molecules form hydration spheres around dissolved ions, keeping them dispersed.
    • Ionic compounds (e.g., NaCl) dissociate into ions when added to water, each ion surrounded by hydration shells.

    Water's Cohesive and Adhesive Properties

    • Cohesion is the attraction between water molecules due to hydrogen bonding, creating surface tension.
    • Surface tension allows objects denser than water to float (e.g., needles on water).
    • Adhesion is the attraction between water molecules and other charged surfaces. Capillary action is an example of adhesion in narrow tubes.
    • Cohesion and adhesion are vital for water transport in plants, and for some insects (e.g., water striders) to stay afloat.

    pH, Buffers, Acids, and Bases

    • pH measures the concentration of hydrogen ions (H⁺) in a solution.
    • Pure water has a neutral pH of 7.0, while acidic solutions have lower pH values, and alkaline solutions have higher pH values.
    • Acids increase H⁺ concentration, while bases decrease it.
    • Strong acids/bases completely dissociate, while weak ones only partially dissociate.
    • Buffers maintain a relatively constant pH by absorbing excess H⁺ or OH⁻ ions. Human blood and cells utilize these buffering systems (carbonic acid/bicarbonate).
    • Stomach acid use buffers (e.g., antacids), due to the need to constantly replace stomach cells that are consumed by stomach acid.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Description

    Test your knowledge with this quiz focused on the unique properties of water as discussed in biology. Explore concepts like hydrogen bonding, heat capacity, and water's role as a solvent. Gain a deeper understanding of why water is essential for life and its implications in biological systems.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser