HMF 1 Lab 1: Membrane Physiology
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Questions and Answers

What is the primary factor that drives the process of diffusion?

  • Particle mass
  • Kinetic energy (correct)
  • Temperature differences
  • Concentration of solute

    • Which of the following factors would NOT affect the rate of diffusion?

  • Color of the solution (correct)
  • Distance travelled
  • Extent of the concentration gradient
  • Nature of the solute

    • What is required for osmosis to occur?

  • Absence of solute in the solution
  • An osmotic gradient and a non-permeable membrane
  • An osmotic gradient and a semi-permeable membrane (correct)
  • Movement of solute across a membrane

    • What happens to a cell placed in a hypertonic solution?

    <p>Water leaves the cell causing it to shrink</p> Signup and view all the answers

    Which characteristics of molecules would increase their diffusion rate across the plasma membrane?

    <p>Smaller size and higher concentration gradient</p> Signup and view all the answers

    In a dialysis experiment using a cellulose tube, what is crucial for maintaining accurate results?

    <p>Keeping the membrane wet and tying off the ends</p> Signup and view all the answers

    Which statement is true regarding diffusion at equilibrium?

    <p>Overall movement of molecules stops, but individual movements continue</p> Signup and view all the answers

    Which type of molecules can typically diffuse through a selectively permeable membrane?

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

    How does an increase in temperature affect the rate of diffusion?

    <p>It enhances the movement of molecules</p> Signup and view all the answers

    Why are cells considered mini-osmometers?

    <p>They regulate their own concentration of solutes and water</p> Signup and view all the answers

    What component is primarily responsible for the semi-permeable nature of the cell membrane?

    <p>Phospholipid bilayer</p> Signup and view all the answers

    What is the primary energy source required for active transport across the cell membrane?

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

    Which factor does NOT influence the degree of Brownian motion of particles in a solution?

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

    According to Fick's Law, how is the velocity of particle movement related to temperature and mass?

    <p>Directly proportional to temperature and inversely proportional to mass</p> Signup and view all the answers

    In the context of solution formation, what is the correct relationship between solute and solvent?

    <p>Solution is a mixture of solute and solvent</p> Signup and view all the answers

    What does Brownian motion primarily result from?

    <p>Random collisions of particles in solution</p> Signup and view all the answers

    Which statement is incorrect regarding the components of the cell membrane?

    <p>Phospholipid bilayer prevents all substances from passing through.</p> Signup and view all the answers

    What characteristic of a solvent is critical for it to dissolve other substances effectively?

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

    Which scenario correctly illustrates passive transport?

    <p>Water moving out of a cell due to osmosis</p> Signup and view all the answers

    Which of the following correctly describes the role of kinetic energy in Brownian motion?

    <p>Increased kinetic energy enhances particle movement.</p> Signup and view all the answers

    What is the effect on a cell when it is immersed in a hypotonic solution?

    <p>The cell will swell and potentially burst.</p> Signup and view all the answers

    Which formula correctly relates osmotic pressure to solute concentration as proposed by van’t Hoff?

    <p>╥ = icsoluteRT</p> Signup and view all the answers

    At which concentration of NaCl will hemolysis likely occur when mixed with sheep's blood?

    <p>0.300M NaCl</p> Signup and view all the answers

    What happens to osmotic pressure when solute concentrations are equal on both sides of a membrane?

    <p>There is no tendency for water movement.</p> Signup and view all the answers

    Which of the following is NOT a variable in the osmotic pressure equation ╥ = icsoluteRT?

    <p>Volume of solution</p> Signup and view all the answers

    What is the primary aim of the centrifuge step in the described procedure?

    <p>To separate the plasma from the red blood cells.</p> Signup and view all the answers

    The correction factor 'i' in the osmotic pressure formula defines what?

    <p>The number of particles the solute dissociates into.</p> Signup and view all the answers

    Which solution is expected to have the highest osmotic pressure in the procedure?

    <p>0.300M Glucose</p> Signup and view all the answers

    What is hematocrit a measure of in blood analysis?

    <p>The percentage of blood volume made up of red blood cells.</p> Signup and view all the answers

    In the given procedure, what indicates that hemolysis has occurred when comparing solutions?

    <p>The solution is transparent.</p> Signup and view all the answers

    Study Notes

    Cell Structure and Membrane Physiology

    • Cell membranes are semi-permeable, maintaining internal conditions by regulating pH, osmolality, and nutrient levels.
    • Composed of a phospholipid bilayer, proteins, glycolipids, and cholesterol; composition varies based on cell function.

    Transport Mechanisms

    • Passive Transport: Movement down a concentration gradient without ATP; relies on pressure/gradient difference.
    • Active Transport: Requires ATP to move substances against their concentration gradient.

    Brownian Motion

    • Discovered by Robert Brown in 1827, refers to the random movement of small particles in a solution due to collision with molecules.
    • Kinetic energy is present in all objects; degree of motion varies: gas > liquid > solid.
    • Influenced by temperature, mass, and environment, as described by Fick's Law (velocity = temp/√mass).

    Solutions and Diffusion

    • Solution: Mixture of solute (substance being dissolved) and solvent (substance doing the dissolving).
    • Diffusion is the passive movement of solute molecules from high to low concentration; driven by kinetic energy without ATP.
    • Factors affecting diffusion include concentration gradient, mass of molecules, temperature, solvent density, solubility, surface area, membrane thickness, and distance.

    Osmosis

    • Defined as the diffusion of water across a semi-permeable membrane from areas of high solvent concentration to low solvent concentration.
    • Requires an osmotic gradient and a semi-permeable membrane for water movement.

    Tonicity and Osmotic Pressure

    • Tonicity describes the influence of a solution on cell shape:
      • Isotonic: Equal concentration of solutes; cell shape remains unchanged.
      • Hypertonic: Higher solute concentration outside the cell; causes cell to shrink.
      • Hypotonic: Lower solute concentration outside; causes cells to swell.
    • Osmotic pressure measures the tendency of a solution to draw in water; proposed by Jacobus van’t Hoff.

    Hematocrit Measurement

    • Measures the packed cell volume (PCV) or the percentage of blood volume made up of red blood cells.
    • Procedure involves centrifuging blood samples and assessing levels of hemolysis and transparency in solutions.

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    Lab 1 Membrane Physiology PDF

    Description

    This quiz covers the fundamental concepts of membrane physiology, focusing on cell organelles and biological membranes. Students will explore the properties and functions of cell membranes, including their semi-permeable nature. Prepare to deepen your understanding of cellular structures and their significance.

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