Cell Membrane Transport Quiz
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Questions and Answers

Which factor does NOT affect the magnitude of diffusion across the cell membrane?

  • Concentration gradient
  • Surface area for diffusion
  • Membrane thickness
  • Temperature of the cytoplasm (correct)

    • What is the correct equation representing the net rate of diffusion (J) across the cell membrane?

  • J = A * D * X / Ac
  • J = D * A * Ac / X (correct)
  • J = D / (A * Ac * X)
  • J = D * (A + Ac) / X

    • Which is NOT a mechanism of passive transport across the cell membrane?

  • Osmosis
  • Facilitated diffusion
  • Primary active transport (correct)
  • Simple diffusion

    • What term describes the movement of molecules from a region of lower concentration to a region of higher concentration?

    <p>Active transport</p> Signup and view all the answers

    Which type of diffusion does NOT involve the assistance of a carrier protein?

    <p>Simple diffusion</p> Signup and view all the answers

    Which statement about osmosis is incorrect?

    <p>It involves the movement of solute molecules.</p> Signup and view all the answers

    In which type of active transport is energy directly consumed to move substances across the membrane?

    <p>Primary active transport</p> Signup and view all the answers

    What is the purpose of endocytosis in cell membrane transport?

    <p>To absorb substances into the cell</p> Signup and view all the answers

    What factor does NOT influence the net rate of diffusion of oxygen across the pulmonary membrane?

    <p>Temperature of the inspired air</p> Signup and view all the answers

    Which substances primarily require transport proteins to cross the lipid bilayer?

    <p>Large uncharged molecules</p> Signup and view all the answers

    Which statement best describes facilitated diffusion?

    <p>It involves structural changes in transport proteins.</p> Signup and view all the answers

    What process describes the diffusion of ions through ion channels?

    <p>Simple diffusion</p> Signup and view all the answers

    In the context of diffusion, what is the significance of the Donnan effect?

    <p>It explains the unequal distribution of diffusible ions.</p> Signup and view all the answers

    Which of the following substances can diffuse rapidly across the lipid bilayer?

    <p>Lipid soluble molecules</p> Signup and view all the answers

    What happens to oxygen diffusion if the area available for diffusion decreases?

    <p>Oxygen diffusion will decrease significantly.</p> Signup and view all the answers

    Which type of molecules utilizes aquaporins for transport across cell membranes?

    <p>Water molecules</p> Signup and view all the answers

    What is the primary function of the sodium-potassium pump in cellular transport?

    <p>It extrudes 3 Na+ out of the cell while bringing 2 K+ in.</p> Signup and view all the answers

    Which characteristic is NOT associated with primary active transport mechanisms?

    <p>Passive movement of solutes.</p> Signup and view all the answers

    How does the sodium-potassium pump contribute to the electrogenic nature of the cell membrane?

    <p>By creating a charge imbalance due to the different number of Na+ and K+ transported.</p> Signup and view all the answers

    In which scenario is solvent drag most appreciable?

    <p>Across the kidney glomeruli.</p> Signup and view all the answers

    What defines the coupling ratio of the sodium-potassium pump?

    <p>3 Na+ for every 2 K+ transported.</p> Signup and view all the answers

    What role does Ca-ATPase play in muscle cells?

    <p>It pumps Ca2+ out of the cytoplasm leading to muscle relaxation.</p> Signup and view all the answers

    What is solvent drag primarily associated with in the context of filtration?

    <p>The high surface area and permeability of the filtering membrane.</p> Signup and view all the answers

    What effect does phosphorylation have in the operation of the sodium-potassium pump?

    <p>It facilitates the binding of Na+ ions to the alpha subunit.</p> Signup and view all the answers

    What characterizes the process of nonionic diffusion?

    <p>It involves the diffusion of undissociated weak acids and bases.</p> Signup and view all the answers

    What is the definition of osmotic pressure?

    <p>The pressure necessary to prevent the movement of water across a membrane.</p> Signup and view all the answers

    Why does a hyperosmolar solution of NaCl exert osmotic effects on cells?

    <p>Sodium is not able to diffuse easily across the cell membrane.</p> Signup and view all the answers

    How does osmosis occur in relation to solute concentration?

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

    What is true regarding ultrafiltration in capillary walls?

    <p>Pressure differences between capillary and interstitial fluid drive the process.</p> Signup and view all the answers

    In which scenario would urea not exert an osmotic effect?

    <p>If it is in equilibrium with cell interior concentrations.</p> Signup and view all the answers

    What prevents the diffusion of weak acids and bases in their ionic forms?

    <p>The membrane's permeability to ionic particles.</p> Signup and view all the answers

    What best describes oncotic pressure?

    <p>The drawing force exerted by plasma proteins alone.</p> Signup and view all the answers

    What role do V-ATPases play in cellular function?

    <p>They transport protons out of the cytoplasm into organelles such as lysosomes.</p> Signup and view all the answers

    Which of the following best describes secondary active transport?

    <p>Couples the transport of a substance with Na+ driven by the Na-K pump.</p> Signup and view all the answers

    What process is characterized by the cell membrane folding inward to form a vesicle?

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

    What is the primary purpose of the sodium-dependent glucose transport in intestinal cells?

    <p>To facilitate the uptake of glucose into cells using Na+ concentration gradient.</p> Signup and view all the answers

    Which statement regarding the sodium-calcium exchange mechanism is correct?

    <p>Na+ moves down its electrochemical gradient while Ca²+ moves against its gradient.</p> Signup and view all the answers

    What is lost during the process of endocytosis?

    <p>Membrane material surrounding the cell</p> Signup and view all the answers

    Which transport system directly influences the electrochemical gradient of sodium in cells?

    <p>Na-K pump</p> Signup and view all the answers

    What is the function of sodium-dependent amino acid transporters in renal cells?

    <p>They co-transport amino acids into renal cells when Na+ binds.</p> Signup and view all the answers

    Which of the following correctly describes the process of phagocytosis?

    <p>It is the engulfment of large particulate matter by certain cells.</p> Signup and view all the answers

    What is immediately formed after the invagination of the cell membrane during pinocytosis?

    <p>Pinocytic vacuole</p> Signup and view all the answers

    Which statement about exocytosis is true?

    <p>It results in the expulsion of cellular secretions.</p> Signup and view all the answers

    Which of the following components plays a crucial role in the docking of secretory vesicles during exocytosis?

    <p>Calcium ions (Ca2+)</p> Signup and view all the answers

    In which process are the contents of vacuoles expelled from the cell after digestion?

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

    What type of cells are primarily responsible for phagocytosis?

    <p>Macrophages and certain white blood cells</p> Signup and view all the answers

    During which process can pinocytic vacuoles either remain unaltered or fuse with lysosomes?

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

    What occurs during the process of cellular defaecation?

    <p>Undigestible materials are expelled from the cell.</p> Signup and view all the answers

    Study Notes

    Chapter 3: Membrane Physiology

    • Transport across cell membranes is crucial for multicellular organisms
    • The internal environment (ECF) composition differs from intracellular fluid (ICF)
    • Differences are due to the cell membrane, which regulates the exchange of materials
    • Transport occurs via passive and active mechanisms

    Passive Transport Mechanisms

    • Diffusion:

      • Simple diffusion: Molecules move down their concentration gradient
      • Facilitated diffusion: Carrier proteins aid movement down the gradient
      • Nonionic diffusion: Movement of uncharged molecules

    • Osmosis: Movement of water across a selectively permeable membrane from an area of higher water concentration to an area of lower concentration

    • Filtration: Movement of small molecules through a membrane due to pressure differences

    Active Transport Mechanisms

    • Primary active transport: Uses energy (ATP) directly to move molecules against their concentration gradient, exemplified by the sodium-potassium pump.
      • The sodium-potassium pump extrudes sodium (3 Na+) and brings in potassium (2 K+)
    • Secondary active transport: Uses the electrochemical gradient of one molecule (often Na+) to move another molecule against its gradient.
      • Examples include glucose transport
    • Endocytosis: Cellular uptake of materials by engulfing them in vesicles
      • Types include phagocytosis (engulfing large particles) and pinocytosis (engulfing fluids or dissolved substances)
    • Exocytosis: Cellular release of materials by fusing vesicles with the cell membrane

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    Description

    Test your knowledge on the mechanisms of cell membrane transport including diffusion, osmosis, and active transport. This quiz covers essential concepts related to the movement of molecules across cell membranes and the factors influencing these processes.

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