Understanding Concentration Gradients and Osmosis
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Questions and Answers

Which of the following statements accurately describes a concentration gradient?

  • It drives the movement of substances from lower to higher concentration.
  • It results in equilibrium when the concentration of substances is equal on both sides of the membrane.
  • It is the equal distribution of substances across a cell membrane.
  • It arises from the unequal distribution of substances, driving movement from higher to lower concentration. (correct)
  • What is the process by which water moves across a selectively permeable membrane?

  • Facilitated diffusion
  • Bulk transport
  • Osmosis (correct)
  • Active transport
  • In the context of osmosis, which of the following solutions would cause water to move into a cell?

  • A hypertonic solution
  • An isotonic solution
  • A hypotonic solution (correct)
  • A solution with the same solute concentration as the cell
  • How is concentration typically represented in the context of solutions?

    <p>With square brackets around the solute of interest</p> Signup and view all the answers

    If a solution is hypertonic compared to another solution, what does this imply about their solute concentrations?

    <p>The hypertonic solution has a higher solute concentration.</p> Signup and view all the answers

    In the context of osmosis, what happens when two solutions are isotonic?

    <p>No net movement of water occurs between the solutions.</p> Signup and view all the answers

    In osmosis, which direction does water move?

    <p>From a hypotonic solution to a hypertonic solution</p> Signup and view all the answers

    What drives the movement of a substance down its concentration gradient?

    <p>Imbalance of solutes between two solutions</p> Signup and view all the answers

    How is equilibrium defined in the context of concentration gradients?

    <p>Equal distribution of substances</p> Signup and view all the answers

    Which type of solution has a higher concentration of solutes?

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

    What happens when two solutions are isotonic?

    <p>They will reach equilibrium</p> Signup and view all the answers

    How is concentration typically represented when discussing solutions?

    <p>[Solute]</p> Signup and view all the answers

    Which of the following statements accurately describes the role of turgor pressure in plant cells?

    <p>Turgor pressure is the force exerted by the cell wall on the cytoplasm, resulting from water entering the cell via osmosis.</p> Signup and view all the answers

    What is the primary function of aquaporins in the context of transmembrane diffusion?

    <p>To selectively allow the passage of water molecules across the membrane, while preventing the diffusion of other substances.</p> Signup and view all the answers

    In the context of red blood cells, what is the primary mechanism used to maintain an isotonic internal environment?

    <p>Active transport of ions across the cell membrane to balance solute concentrations.</p> Signup and view all the answers

    Which of the following statements accurately describes the relationship between polarity and size in the context of transmembrane diffusion?

    <p>Both polarity and size are important factors that determine the ability of a molecule to diffuse across the phospholipid bilayer.</p> Signup and view all the answers

    Consider a plant cell in a hypotonic solution. Which of the following statements accurately describes the resulting effects on the cell?

    <p>Water will move into the cell, increasing turgor pressure and causing the cell to become turgid.</p> Signup and view all the answers

    Which statement accurately describes the relationship between polarity, size, and transmembrane diffusion?

    <p>Polar and small molecules can diffuse through the hydrophobic interior of a phospholipid bilayer, while non-polar and large molecules cannot.</p> Signup and view all the answers

    What is the primary mechanism by which red blood cells maintain an isotonic internal environment?

    <p>Active transport of ions to balance solute concentrations</p> Signup and view all the answers

    In the context of plant cells, what is the primary function of turgor pressure?

    <p>To provide structural support and protection to the cell</p> Signup and view all the answers

    Which of the following statements accurately describes the process of osmosis across a lipid bilayer?

    <p>Water moves through the hydrophobic interior of the bilayer or through aquaporins, while solutes cannot cross the bilayer.</p> Signup and view all the answers

    In the context of solutions, what is the primary factor that determines the direction of osmosis?

    <p>The concentration gradient of solutes</p> Signup and view all the answers

    Study Notes

    Concentration Gradients

    • A concentration gradient occurs when there is an unequal distribution of substances (e.g., ions, glucose molecules) in a cell or across a cell membrane.
    • This imbalance of solutes between two solutions drives the movement of a substance from a region of higher concentration to a region of lower concentration.
    • Equilibrium is reached when there is no longer a concentration gradient.

    Osmosis

    • Osmosis is the passive transport of water across a selectively permeable membrane.
    • Water diffuses from a region of higher water concentration (lower solute concentration) to a region of lower water concentration (higher solute concentration).
    • Concentration refers to the amount of a substance in a defined space (amount/volume).

    Hypertonic and Hypotonic Solutions

    • A hypertonic solution has a higher concentration of solutes.
    • A hypotonic solution has a lower concentration of solutes.
    • Solutions are isotonic if they have the same concentrations of solutes.
    • In osmosis, water moves from a hypotonic solution to a hypertonic solution.

    Transmembrane Diffusion

    • The most important parameters that govern transmembrane diffusion are polarity and size.
    • Water is polar, but also small, allowing it to pass through the hydrophobic interior of a phospholipid bilayer.

    Cell Shape and Osmosis

    • Osmosis can affect cell shape.
    • Red blood cells use active transport of ions to keep the internal environment of the cell isotonic to the external environment.
    • Cell shape and size in red blood cells change based on the solute concentration surrounding the cells.

    Cell Walls and Turgor Pressure

    • The cell wall provides structural support and protection.
    • Turgor pressure within the cell occurs when water moves into the cell through osmosis.
    • Water can move across a lipid bilayer via simple diffusion (osmosis) or via facilitated transport through water-selective channels (aquaporins).

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    Description

    Learn about concentration gradients, the movement of substances across membranes due to uneven distributions, and how osmosis allows the passive transport of water. Explore the concept of equilibrium in terms of solute concentrations.

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