Cell Transport Mechanisms Quiz
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Questions and Answers

What is a characteristic feature of exocytosis?

  • It primarily occurs through passive transport mechanisms.
  • It requires energy and involves the secretion of vesicles. (correct)
  • It does not require plasma membrane fusion.
  • It transports materials into the nucleus.

    • Which of the following best describes endocytosis?

  • An example of passive transport across a membrane.
  • A process that moves substances out of the cell.
  • A mechanism that does not involve energy usage.
  • An energy-dependent method for importing large particles. (correct)

    • What process describes the movement of water across a semi-permeable membrane?

  • Active transport
  • Facilitated diffusion
  • Endocytosis
  • Osmosis (correct)

    • In osmosis, water moves from areas of ____ water concentration to areas of ____ water concentration.

    <p>high; low</p> Signup and view all the answers

    When conducting an osmosis experiment with potato pieces, which solution will most likely cause the potato to lose the most water?

    <p>10% NaCl</p> Signup and view all the answers

    Which transport mechanism uses energy to move substances across the cell membrane?

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

    Which of the following statements correctly describes simple diffusion?

    <p>It does not require energy.</p> Signup and view all the answers

    According to Fick's law of diffusion, which factor does NOT affect the diffusion rate?

    <p>Color of the substance</p> Signup and view all the answers

    What is the primary difference between primary and secondary active transport?

    <p>Primary uses ATP directly, secondary uses it indirectly.</p> Signup and view all the answers

    Which type of transport involves the movement of macromolecules across the cell membrane?

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

    What term describes the pressure required to prevent the flow of water across a semipermeable membrane?

    <p>Osmotic pressure</p> Signup and view all the answers

    In which type of transport do particles move according to their concentration gradient?

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

    What must be true for a substance to passively diffuse through the cell membrane?

    <p>It must be lipid-soluble.</p> Signup and view all the answers

    What role do hormones play in glucose transport in the body?

    <p>They increase the number of glucose carriers.</p> Signup and view all the answers

    Which type of transport requires energy?

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

    In facilitated diffusion, what is used to help transport particles across the membrane?

    <p>Carrier proteins</p> Signup and view all the answers

    What describes the sodium-potassium pump?

    <p>It transports potassium against its concentration gradient.</p> Signup and view all the answers

    Which of the following correctly defines secondary active transport?

    <p>It moves molecules against their gradient without using energy directly.</p> Signup and view all the answers

    What characterizes primary active transport?

    <p>It directly uses ATP to move ions against their concentration gradient.</p> Signup and view all the answers

    Which of the following best describes simple diffusion?

    <p>Does not require cellular energy.</p> Signup and view all the answers

    How does diabetes mellitus affect glucose transport?

    <p>It decreases the number of glucose carriers.</p> Signup and view all the answers

    Which of the following statements about energy in transport processes is incorrect?

    <p>Simple diffusion consumes ATP to occur.</p> Signup and view all the answers

    Which factor primarily influences the number of carriers present for glucose transport?

    <p>Hormonal levels.</p> Signup and view all the answers

    What is the relationship between temperature and the rate of diffusion as described in the content?

    <p>Increasing temperature increases the rate of diffusion.</p> Signup and view all the answers

    Which statement best describes why charged molecules have low diffusion rates through cell membranes?

    <p>Hydrated ions have a large size obstructing entry.</p> Signup and view all the answers

    What distinguishes ligand-gated channels from leakage channels?

    <p>Ligand-gated channels open in response to specific molecules.</p> Signup and view all the answers

    What is the function of the ion channels mentioned in the content?

    <p>They allow ions to move according to their electrochemical gradient.</p> Signup and view all the answers

    How does the surface area of a membrane influence diffusion according to the provided equation?

    <p>Higher surface area enhances diffusion rates.</p> Signup and view all the answers

    What characteristic distinguishes leakage channels from other types of ion channels?

    <p>They are always open and selective.</p> Signup and view all the answers

    What is the primary role of sodium in the extracellular fluid (ECF)?

    <p>To serve as the chief ECF cation</p> Signup and view all the answers

    What role does molecular weight play in the rate of diffusion?

    <p>Substances with lower molecular weights diffuse faster.</p> Signup and view all the answers

    What type of gated channel responds to chemical signals like neurotransmitters?

    <p>Ligand gated channels</p> Signup and view all the answers

    How do local anesthetics affect sodium channels?

    <p>By binding to voltage gated Na channels and blocking Na entry</p> Signup and view all the answers

    In the context of diffusion through membranes, what is the effect of hydrated ions?

    <p>They slow down diffusion due to increased size.</p> Signup and view all the answers

    Which channel type is specifically mentioned as a way for ions to diffuse across a membrane?

    <p>Voltage-gated channels</p> Signup and view all the answers

    What is facilitated diffusion primarily dependent on?

    <p>Concentration gradient and carrier proteins</p> Signup and view all the answers

    What does the abbreviation 'ECF' stand for in the context of ion leakage channels?

    <p>Extracellular Fluid</p> Signup and view all the answers

    What is meant by the transport maximum in cellular transport?

    <p>The maximum rate at which specific solutes can be transported</p> Signup and view all the answers

    What characterizes voltage-gated channels?

    <p>They open or close based on membrane electrical potential.</p> Signup and view all the answers

    Which ion is primarily maintained as the chief intracellular cation?

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

    What is the main reason sodium enters a cell during depolarization?

    <p>Voltage changes triggering sodium channels to open</p> Signup and view all the answers

    What is the effect of facilitated diffusion on glucose transport?

    <p>It allows glucose to move according to its concentration gradient</p> Signup and view all the answers

    Which type of channel is affected by changes in membrane potential?

    <p>Voltage gated channels</p> Signup and view all the answers

    Study Notes

    Module Information

    • Module: HUMAN BODY FUNCTION (HBF-102)
    • Academic Year: 2024/2025
    • Year: 1
    • Semester: 1

    Transport Across the Cell Membrane

    • The transport across cell membranes can be passive or active.
    • Passive transport doesn't require energy, while active transport does.
    • Passive transport includes simple diffusion and facilitated diffusion.
    • Active transport can be primary or secondary.

    Objectives

    • Differentiate between the types of transport across cell membranes
    • List different types of channels
    • Identify different types of carriers
    • Explain how macromolecules cross cell membranes
    • Define osmosis and osmotic pressure

    Active vs Passive Transport

    • Active transport moves molecules against the concentration gradient. It requires energy.
    • Passive transport moves molecules with the concentration gradient. It doesn't require energy.

    Simple Diffusion

    • Simple diffusion is a passive transport.
    • It doesn't require energy or carriers.
    • Molecules move from an area of high concentration to an area of low concentration.
    • It's affected by Fick's law of diffusion.

    Fick's Law of Diffusion

    • Diffusion rate is directly proportional to the permeability coefficient, concentration gradient, and surface area.
    • Diffusion rate is inversely proportional to the thickness of the membrane.
    • Increasing temperature increases the rate of diffusion.

    Demonstration of Diffusion in Fluids

    • Place methylene blue crystals in beakers with different temperatures (cold, room temperature, hot) of water.
    • Observe and record the time it takes for the dye to disperse evenly in each beaker.

    Charged Molecules and Cell Membranes

    • Charged molecules diffuse across cell membranes at an extremely low rate.
    • This is due to the formation of large hydrated ions with water, and the interaction between charges on the molecules and membrane.

    Ion Channels

    • Ion channels are important for ion diffusion.
    • Ions move through these channels by simple diffusion, following their electrochemical gradient.
    • Types include leakage, voltage-gated, and ligand-gated channels.

    Leakage Channels

    • Leakage channels are water pathways through integral proteins in the cell membrane.
    • They are tubular and extend from the extracellular fluid (ECF) to the intracellular fluid (ICF).
    • These channels are highly selective.
    • Examples include Na+ and K+ leakage channels.

    Gated Channels

    • Gated channels have gates that open or close in response to specific signals.
    • Ligand-gated channels open or close when a specific molecule (ligand) binds to them, like neurotransmitters.
    • Voltage-gated channels open or close in response to changes in membrane potential.
    • Examples of voltage-gated channels include Na+ and K+ voltage-gated channels.

    Role of Sodium Channels in Local Anesthesia

    • Local anesthetics bind to voltage-gated sodium channels.
    • Binding blocks sodium entry into the cell.
    • This prevents the generation and conduction of action potentials (no pain sensation).

    Facilitated Diffusion

    • Facilitated diffusion is a passive transport that requires a carrier protein.
    • Molecules move from high to low concentration.
    • It has a transport maximum.
    • An example is the transport of glucose.

    Transport Maximum

    • Transport maximum is the maximal rate at which a substance can be transported by facilitated diffusion.
    • It depends on the number of carriers in the membrane.
    • Affected by hormones (e.g., insulin). An increase in Insulin increases the rate of glucose carrier.

    Active Transport

    • Active transport is uphill/against the concentration gradient, and thus requires energy from ATP.
    • It involves carrier proteins.
    • Types are primary active transport and secondary active transport

    Primary Active Transport

    • Carriers have ATPase activity.
    • This type of transport moves molecules 'uphill' against their concentration gradient.
    • Includes Na+-K+ pump, Ca2+ pump, and H+-K+ pump.

    Secondary Active Transport

    • This type of transport depends on the sodium gradient created by the sodium-potassium pump.
    • It is either cotransport (symport) or countertransport (antiport).

    Exocytosis

    • Transports material to outside the cell.
    • An active transport process that requires energy.
    • Example: Transport of acetylcholine at the motor end plate.

    Endocytosis

    • Transport of materials into the cell.
    • Active process that requires energy.
    • Example: Phagocytosis of bacteria and dead tissue.

    Osmosis

    • Passive transport of water across a semi-permeable membrane.
    • Water moves from an area of high water concentration (low solute concentration) to an area of low water concentration (high solute concentration).

    Osmotic Pressure

    • Pressure required to prevent osmosis.

    Isotonic, Hypotonic, Hypertonic Solutions

    • Isotonic: Solute concentration inside the cell equals the solution outside the cell.
    • Hypotonic: Solute concentration inside the cell is higher than outside. Water moves into the cell.
    • Hypertonic: Solute concentration inside the cell is lower than outside. Water moves out of the cell.

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    Related Documents

    Lab 1 Transport Across Cell Membrane PDF 2024/2025

    Description

    This quiz tests your understanding of various cell transport mechanisms, including exocytosis, endocytosis, osmosis, and diffusion. Explore the processes that govern the movement of substances across cell membranes and their implications. Perfect for biology students looking to reinforce their knowledge in cell biology.

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