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Introduction to Membrane Transport quiz #2

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  • What is mediated transport?
    Mediated transport refers to the movement of substances across a cell membrane with the help of transport proteins. This includes facilitated diffusion and active transport, where specific proteins assist in moving molecules that cannot freely diffuse across the membrane.
  • How do substances move across a selectively permeable membrane?
    Substances move across a selectively permeable membrane through passive transport (such as diffusion and osmosis) and active transport, which may require energy and transport proteins for larger, charged, or polar molecules.
  • What is an example of antiport transport?
    a) Sodium-potassium pump. Antiport involves the movement of two substances in opposite directions across a membrane.
  • Which transport process requires a transport protein?
    c) Facilitated diffusion. This process requires transport proteins to help move substances across the membrane.
  • Which is not a type of mediated transport? a) Simple diffusion b) Facilitated diffusion c) Active transport d) Endocytosis
    a) Simple diffusion. This process does not require transport proteins and is not considered mediated transport.
  • Which cell lysis technique uses high-frequency sound to disrupt the membrane?
    b) Sonication. This technique uses high-frequency sound waves to break cell membranes.
  • What is an example of secondary active transport?
    b) Glucose-sodium symport. Secondary active transport uses the energy from the electrochemical gradient of one molecule to transport another molecule.
  • Glucose enters the cell by which process?
    Glucose enters the cell primarily through facilitated diffusion using a specific glucose transporter protein.
  • What does it mean when a biological membrane is described as selectively permeable?
    A selectively permeable membrane allows only certain molecules to cross while blocking others, based on their properties.
  • Why can't large, charged, or polar molecules freely cross biological membranes?
    Large, charged, or polar molecules cannot freely cross membranes because their size, charge, or polarity prevents them from passing through the hydrophobic core of the lipid bilayer.
  • What is bulk transport in the context of membrane transport?
    Bulk transport refers to the movement of large molecules or particles across the membrane via processes like endocytosis and exocytosis.
  • What property of the membrane makes it 'picky' about what crosses it?
    The membrane's selective permeability, due to its lipid bilayer structure, makes it picky about which molecules can cross.
  • What is the main function of endocytosis?
    Endocytosis allows cells to take in large molecules or particles by engulfing them with the cell membrane.
  • What are the two main categories of membrane transport?
    The two main categories are molecular transport (for small molecules) and bulk transport (for large molecules).
  • How does the size of a molecule affect its ability to cross the membrane?
    Smaller molecules can cross the membrane more easily, while larger molecules are typically blocked unless transported by proteins or bulk transport mechanisms.
  • Which property is shared by molecules that cannot freely diffuse across the membrane?
    Molecules that cannot freely diffuse are typically large, charged, or polar (hydrophilic).
  • What is the difference between molecular transport and bulk transport?
    Molecular transport involves the movement of small molecules, while bulk transport involves the movement of large molecules or particles.
  • What is the significance of membrane transport for cellular homeostasis?
    Membrane transport regulates the internal environment of the cell, maintaining homeostasis by controlling the movement of substances in and out.
  • What is the main difference between simple diffusion and facilitated diffusion?
    Simple diffusion occurs without proteins, while facilitated diffusion requires transport proteins to help molecules cross the membrane.
  • What is receptor-mediated endocytosis?
    Receptor-mediated endocytosis is a type of endocytosis where specific molecules are taken into the cell after binding to receptors on the membrane.
  • What is pinocytosis and what does it accomplish for the cell?
    Pinocytosis is 'cellular drinking,' where the cell engulfs extracellular fluid and dissolved solutes into small vesicles.