Cell Membrane Transport Quiz
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Cell Membrane Transport Quiz

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Questions and Answers

What is the primary requirement for passive transport to occur?

  • Molecules must be actively bonded to the membrane.
  • Energy expenditure is required for movement.
  • All solutes must be at the same concentration.
  • There must be a concentration gradient. (correct)
  • Which of the following processes do NOT involve the expenditure of energy?

  • Facilitated Diffusion (correct)
  • Osmosis (correct)
  • Endocytosis
  • Protein Pumps
  • How is concentration mathematically defined in a solution?

  • The sum of solute mass plus solvent volume.
  • The product of solute mass and solvent volume.
  • The mass of solute divided by the volume of solvent. (correct)
  • The volume of solvent divided by solute mass.
  • In diffusion, which statement best describes the movement of solute particles?

    <p>They move from high to low concentration until equilibrium is reached.</p> Signup and view all the answers

    Which of the following processes is an example of active transport?

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

    What is the primary role of carrier proteins in facilitated diffusion?

    <p>To change shape and assist in moving particles</p> Signup and view all the answers

    Under which circumstances would diffusion occur the slowest?

    <p>At low concentrations and low temperatures</p> Signup and view all the answers

    In a hypertonic solution, which of the following occurs?

    <p>Water moves out of the cell</p> Signup and view all the answers

    Which type of molecules diffuse easily across the phospholipid bilayer?

    <p>Small, non-polar molecules</p> Signup and view all the answers

    What characterizes facilitated diffusion as compared to simple diffusion?

    <p>It involves specific proteins for certain molecules</p> Signup and view all the answers

    Study Notes

    Cell Membrane Transport

    • Cells need to move substances across their membrane to maintain homeostasis.
    • The cell membrane acts as a barrier, controlling the movement of molecules from one side to the other.
    • Concentration is the amount of solute in a solvent. Higher concentration means more solute.
    • To calculate concentration, divide the mass of the solute by the volume of the solvent.

    Transport Methods

    • Passive transport does not require energy.
    • Active transport requires energy.

    Passive Transport: Diffusion

    • Molecules move from a region of high concentration to an area of low concentration.
    • This movement continues until equilibrium is reached, where the concentration of solutes is equal on both sides of the membrane.
    • Solutes move down their concentration gradient, moving from high to low concentration.
    • The rate of diffusion is affected by:
      • Concentration: Higher concentration leads to faster diffusion.
      • Temperature: Higher temperature leads to faster diffusion.
      • Pressure: Higher pressure leads to faster diffusion.

    Diffusion: Non-Polar Molecules

    • Small, non-polar molecules diffuse easily across the phospholipid bilayer of a cell membrane.
    • Example: Oxygen enters red blood cells and carbon dioxide leaves them in the lungs through passive transport.

    Facilitated Diffusion

    • Large, polar, or charged molecules cannot cross the lipid bilayer on their own.
    • These molecules require the assistance of transport proteins.
    • Each protein is specific to a particular molecule.
    • Channel proteins open and close to allow substances to cross the membrane.
    • Carrier proteins change shape to move particles across the membrane.

    Osmosis

    • Water diffuses across a selectively permeable membrane from an area of high water concentration to an area of low water concentration.
    • Hypertonic solution: Has a higher solute concentration and lower water concentration than the cell. Water moves out of the cell.
    • Hypotonic solution: Has a lower solute concentration and higher water concentration than the cell. Water moves into the cell.
    • Isotonic solution: Has the same solute concentration as the cell. No net movement of water.

    Osmoregulation

    • Animals need to control water balance to survive in hypotonic or hypertonic environments.
    • This process is called osmoregulation.
    • Example: Freshwater fish have kidneys and gills to prevent water buildup.
    • In a hypertonic solution, an animal cell shrivels.
    • In a hypotonic solution, an animal cell swells or lyses (bursts).

    Water Balance in Plants

    • Plant cells have rigid cell walls.
    • Isotonic solution: Plant cell is flaccid and wilts.
    • Hypotonic solution: Plant cell is turgid and healthy. The cell wall prevents the cell from bursting.
    • Hypertonic solution: Plant cell loses water, and the plasma membrane pulls away from the cell wall, called plasmolysis.

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    Description

    Test your knowledge on cell membrane transport mechanisms, including passive and active transport. Understand how molecules move across membranes and the role of concentration gradients in diffusion. This quiz will help reinforce concepts of homeostasis in cells.

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