BIOL 150 Lecture 3 (p.1-35)
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Questions and Answers

What percentage of the human body is typically composed of water?

  • 30-50%
  • 75-90%
  • 10-30%
  • 50-75% (correct)
  • Why is water classified as a polar molecule?

  • It has equal distribution of charge.
  • It contains a net positive charge.
  • It only exists in solid form.
  • It has an uneven distribution of charge. (correct)
  • Which statement accurately describes the existence of water in physical states?

  • Water only exists in liquid and gas forms.
  • Water can exist in all three physical states: solid, liquid, and gas. (correct)
  • Water does not exist as a solid in nature.
  • Water is only found as a gas in the environment.
  • What defines the polarity of a molecule?

    <p>Difference in electronegativity and asymmetric geometry.</p> Signup and view all the answers

    Which of the following is true regarding the bonding in water molecules?

    <p>Oxygen has a greater pull on shared electrons than hydrogen.</p> Signup and view all the answers

    What unique behavior does water exhibit when temperatures decrease past 4˚C?

    <p>It expands.</p> Signup and view all the answers

    Why does ice float on water?

    <p>Ice is less dense than liquid water.</p> Signup and view all the answers

    How does surface tension in water benefit certain organisms?

    <p>It allows them to skate on the surface.</p> Signup and view all the answers

    What is the primary function of osmosis in living organisms?

    <p>To maintain homeostasis.</p> Signup and view all the answers

    What happens to water molecules when it is dropped onto wax paper?

    <p>They maintain a spherical shape.</p> Signup and view all the answers

    Which of the following statements about osmosis is correct?

    <p>Water moves from low solute concentration to high solute concentration.</p> Signup and view all the answers

    Which of these elements is known for producing hard alloys for specific uses?

    <p>Osmium.</p> Signup and view all the answers

    What characteristic of water contributes to its high surface tension?

    <p>Strong cohesion among molecules.</p> Signup and view all the answers

    What unique capability does a single water molecule have regarding hydrogen bonds?

    <p>It can form up to four hydrogen bonds.</p> Signup and view all the answers

    What is the fourth state of water called?

    <p>Supercritical fluid</p> Signup and view all the answers

    How does a decrease in temperature affect hydrogen bonding in water?

    <p>It slows down the movement of water molecules, reducing hydrogen bond interactions.</p> Signup and view all the answers

    Which of the following properties of water is significantly influenced by hydrogen bonds?

    <p>Its high specific heat capacity.</p> Signup and view all the answers

    What happens to water molecules when hydrogen bonds are no longer broken due to low temperatures?

    <p>They become locked in place, forming ice.</p> Signup and view all the answers

    Which of the following statements about hydrogen bonds in water is accurate?

    <p>Hydrogen bonds are weaker than covalent bonds.</p> Signup and view all the answers

    What is required for water to exist in its supercritical state?

    <p>Extremely high temperature and pressure.</p> Signup and view all the answers

    What role do hydrogen bonds play in water's unique properties?

    <p>They contribute to many properties that make water integral to life.</p> Signup and view all the answers

    What is cohesion in relation to water?

    <p>Attraction between water molecules through hydrogen bonds.</p> Signup and view all the answers

    What is adhesion responsible for when water droplets cling?

    <p>Water droplets clinging to other polar substances like spider webs.</p> Signup and view all the answers

    What phenomenon describes water rising in a straw?

    <p>Capillary action.</p> Signup and view all the answers

    What limits the extent of capillary action?

    <p>Gravity and the size of the straw.</p> Signup and view all the answers

    How does surface tension affect capillary action?

    <p>It straightens the surface, aiding the rise of water.</p> Signup and view all the answers

    Why does water climb higher in a thinner straw when capillary action occurs?

    <p>Adhesive forces are stronger in thinner straws.</p> Signup and view all the answers

    Which of the following correctly describes the relation between adhesive forces and gravity in capillary action?

    <p>Capillary action stops when adhesive forces are balanced by gravity.</p> Signup and view all the answers

    What is NOT a characteristic of cohesive property of water?

    <p>Clinging to spider webs.</p> Signup and view all the answers

    What is responsible for the movement of water up through the xylem in plants?

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

    What does high specific heat capacity of water allow it to do in temperature regulation?

    <p>Absorb a lot of heat before temperature rises</p> Signup and view all the answers

    What does the term 'heat of vaporization' refer to in the context of water?

    <p>The energy required to break hydrogen bonds for evaporation</p> Signup and view all the answers

    How does water help regulate the Earth's climate?

    <p>Through heat release during water vapor condensation</p> Signup and view all the answers

    Compared to other molecules of its size, what is notable about water's boiling point?

    <p>It is the highest due to the presence of hydrogen bonds</p> Signup and view all the answers

    More than ______% of Earth is covered by water.

    <p>70</p> Signup and view all the answers

    Most plants and animals contain more than ______% water by volume.

    <p>60</p> Signup and view all the answers

    Water is the only common substance to exist in all 3 physical states: solid, liquid, and ______.

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

    Oxygen is more ______ than hydrogen in a water molecule.

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

    A polar molecule must have an asymmetric geometry so that the bond dipoles do not ______ each other.

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

    Oxygen carries a slightly ______ charge in a water molecule.

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

    One water molecule can form up to ______ hydrogen bonds.

    <p>4</p> Signup and view all the answers

    When temperature decreases, water molecules slow down and interact with one another ______.

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

    The fourth state of water, known as ______ fluid, has both liquid and gas properties.

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

    Eventually, hydrogen bonds will no longer be broken, causing water molecules to be locked in place and form ______.

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

    Hydrogen bonds contribute significantly to water's ______, which is vital for life.

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

    Supercritical water is found in extreme conditions, like those at vents on the ______ Ocean's floor.

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

    In liquid water, molecules are constantly breaking and reforming ______ with each other.

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

    Surface tension and capillary action are responsible for the movement of water up through the ______ in plants.

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

    Water has high specific heat capacity, meaning it can absorb a lot of heat before its temperature ______.

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

    The amount of energy required for liquid water to boil and become steam is called the heat of ______.

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

    As warm tropical air moves towards the poles, water vapor releases heat as it ______ into rain.

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

    Water's high boiling point is due to its strong ______ bonds.

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

    As temperature decreases, most liquids contract, but water expands after reaching ______˚C.

    <p>4</p> Signup and view all the answers

    Osmosis occurs when water moves from an area of low ______ concentration to an area of high concentration.

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

    The phenomenon that allows water striders to 'skate' across a pond is known as ______ tension.

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

    At freezing temperature, the volume of water is about ______% higher than in its liquid state.

    <p>9</p> Signup and view all the answers

    Water has the highest surface tension of all non-metallic ______.

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

    Each molecule in a water drop is attracted to ______ other, contributing to its cohesive properties.

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

    Lithium is used in rechargeable batteries for ______ phones and electric vehicles.

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

    Osmosis is one of the most important ways that plants and animals achieve ______.

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

    Cohesion occurs when water is attracted to other water through ______ bonds.

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

    Adhesion allows water to be attracted to other ______.

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

    Capillary action is what you see when you place a straw into a glass of water and the water begins to ______ up the straw.

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

    The thinner the straw, the ______ up capillary action will pull the water.

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

    Surface tension tends to ______ the surface of water.

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

    Capillary action is related to the ______ properties of water.

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

    The force of gravity is balanced by the adhesive force when capillary action ______.

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

    Water droplets clinging to a spider web is an example of ______.

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

    Study Notes

    Importance of Water

    • Over 70% of Earth's surface is covered by water, making it essential for life.
    • All living organisms consist primarily of water, with most plants and animals containing over 60%.
    • The human body is approximately 50-75% water by volume.

    Uniqueness of Water

    • Water is the only substance that naturally exists in all three physical states: solid (ice), liquid (water), and gas (steam).

    Structure of Water

    • Water is a polar molecule; it has an uneven distribution of charge due to oxygen’s higher electronegativity compared to hydrogen.
    • Oxygen holds a slight negative charge (δ-), while hydrogen has a slight positive charge (δ+).

    Chemical Polarity

    • Polarity results from the separation of electric charge, leading to asymmetrical molecules and the presence of an electric dipole moment.
    • Polar molecules contain polar bonds, which must possess a difference in electronegativity.

    Hydrogen Bonding

    • Polar nature allows water to form hydrogen bonds; each water molecule can create up to four H-bonds with neighboring molecules.
    • Hydrogen bonds are crucial for many of water’s unique properties that support life.

    States of Water

    • Water can also exist as a supercritical fluid, a unique state where liquid and gas properties merge, typically found under extreme temperatures and pressures.

    Density of Water

    • The density of water is approximately 1 g/cm³.
    • Water behaves uniquely as it contracts until reaching 4°C and then expands upon freezing, resulting in ice being about 9% less dense than liquid water. This is why ice floats.

    Surface Tension

    • Water has the highest surface tension among non-metallic liquids due to the cohesive forces between molecules at the surface.
    • Surface tension allows small organisms, like water striders, to move across water surfaces.

    Osmosis

    • Osmosis is the movement of water through a semipermeable membrane from an area of low solute concentration to high solute concentration.
    • It enables essential processes for maintaining homeostasis in plants and animals.

    Cohesion and Adhesion

    • Cohesion refers to water’s attraction to other water molecules due to hydrogen bonding.
    • Adhesion is the attraction between water and other polar substances, such as spider silk.

    Capillary Action

    • Capillary action is driven by the adhesive properties of water, causing it to rise against gravity in thin spaces, such as the xylem of plants.
    • Water's movement is also influenced by surface tension, which helps pull other water molecules along.

    Temperature Regulation

    • Water has a high specific heat capacity, meaning it absorbs significant heat before raising its temperature, crucial for temperature regulation in organisms.
    • Water has an extremely high boiling point (100°C) due to hydrogen bonding, requiring substantial energy to convert from liquid to gas (heat of vaporization).

    Climate and Ecosystem Impact

    • Water regulates Earth's climate by absorbing solar heat, which is released during evaporation.
    • This process stabilizes temperatures in aquatic ecosystems and helps prevent overheating in organisms.

    Importance of Water

    • Covers over 70% of Earth's surface and is vital for all life forms.
    • Most plants and animals contain more than 60% water; humans are composed of 50-75% water.

    Uniqueness of Water

    • Exists in all three physical states: solid, liquid, and gas.
    • Water is a polar molecule with an uneven distribution of charge, creating an electric dipole.

    Chemical Polarity

    • Polar molecules have distinct charges due to differences in electronegativity, leading to asymmetric geometries.
    • Allows water molecules to form hydrogen bonds, with one water molecule capable of forming up to four hydrogen bonds.

    States of Water

    • A fourth state exists, known as a supercritical fluid, which occurs under extreme temperature and pressure, merging liquid and gas properties.
    • In liquid water, hydrogen bonds are constantly breaking and reforming; cooling slows movement and eventually locks molecules in place as ice.

    Density of Water

    • Density is approximately 1 g/cm³.
    • Water expands upon freezing, having a volume about 9% higher than in its liquid state, causing ice to float and impacting natural phenomena like frozen pipes.

    Surface Tension

    • Highest surface tension among non-metallic liquids due to the cohesion of water molecules at the surface.
    • Allows insects like water striders to walk on water and influences water droplet formation.

    Osmosis

    • Movement of water from low solute concentration to high solute concentration through semipermeable membranes, crucial for maintaining homeostasis in living organisms.

    Cohesion and Adhesion

    • Cohesion refers to water's attraction to itself via hydrogen bonds; adhesion describes water's attraction to other polar substances.
    • Capillary action leads to the ability of water to rise in narrow spaces, influenced by adhesion and cohesion forces.

    Temperature Regulation

    • High specific heat capacity means water can absorb considerable heat without significantly changing temperature, providing stability in biological systems.
    • Water has a high boiling point and heat of vaporization, regulating the Earth's climate by absorbing and releasing solar energy during evaporation and condensation.

    Implications in Biology

    • Cohesion and adhesion facilitate water movement in xylem vessels in plants, essential for nutrient transport and stability in ecosystems.

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    Description

    In Lecture 3 of BIOL 150, we explore the structure and properties of water, highlighting its crucial role in sustaining life on Earth. Learn about water's unique characteristics and its importance as a major constituent of all life forms, including plants and animals.

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