CR Biology A M2L5
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What is the primary factor that drives the process of diffusion?

  • The type of solvent used
  • The concentration gradient (correct)
  • Temperature of the environment
  • The size of the molecules

    • What is the outcome of the diffusion process?

  • The proteins become inactive
  • A higher concentration of solutes on one side of the membrane
  • The elimination of the concentration gradient (correct)
  • An increase in temperature of the solution

    • How is facilitated diffusion different from simple diffusion?

  • Facilitated diffusion does not reach equilibrium
  • Facilitated diffusion involves transport proteins (correct)
  • Facilitated diffusion requires energy input
  • Facilitated diffusion occurs faster than simple diffusion

    • Which statement describes passive transport?

    <p>It moves solutes down the concentration gradient</p> Signup and view all the answers

    Why might a molecule require facilitated diffusion to cross the cell membrane?

    <p>It cannot dissolve in the phospholipid bilayer</p> Signup and view all the answers

    What happens to an animal cell placed in a hypertonic environment?

    <p>It shrivels and loses water.</p> Signup and view all the answers

    How do plant cells respond to a hypotonic environment?

    <p>They become turgid due to osmotic pressure.</p> Signup and view all the answers

    What role does the cell wall play in plant cells during osmosis?

    <p>It helps maintain water balance and turgor pressure.</p> Signup and view all the answers

    What is the purpose of the contractile vacuole in freshwater protists?

    <p>To remove excess water.</p> Signup and view all the answers

    What type of transport allows small molecules to move across the membrane without energy input?

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

    Which of the following molecules can easily pass through the phospholipid bilayer?

    <p>Carbon dioxide (CO2)</p> Signup and view all the answers

    What is the effect on a freshwater fish placed in saltwater?

    <p>It loses water and may die.</p> Signup and view all the answers

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

    <p>To act as a pore for rapid passage of polar molecules or ions</p> Signup and view all the answers

    Which mechanism is primarily responsible for the diffusion of water molecules across a selectively permeable membrane?

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

    What happens to a freshwater fish when placed in a saltwater environment?

    <p>It will lose water due to osmosis and potentially die</p> Signup and view all the answers

    Which of the following statements about carrier proteins is true?

    <p>They change shape to transport specific molecules across the membrane</p> Signup and view all the answers

    What characterizes a hypertonic solution in osmotic terms?

    <p>Higher solute concentration than another solution</p> Signup and view all the answers

    What triggers the opening of a gated channel protein?

    <p>Chemical or electrical stimuli</p> Signup and view all the answers

    When a cell is placed in a hypotonic solution, what is the expected consequence?

    <p>The cell will swell and possibly lyse</p> Signup and view all the answers

    Which type of protein is used for the transport of ions like sodium and calcium across the cell membrane?

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

    Polar molecules can easily diffuse across the cell membrane without a transport protein.

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

    Aquaporins are a type of channel protein that allow water to diffuse across the membrane quickly.

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

    Diffusion moves molecules from an area of lower concentration to an area of higher concentration.

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

    Facilitated diffusion requires energy input to assist solutes in crossing the cell membrane.

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

    Carrier proteins can change shape to transport large molecules across the membrane.

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

    The concentration gradient is eliminated when diffusion results in an equal concentration of molecules on both sides of the membrane.

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

    Cells in a hypertonic solution will generally swell and burst.

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

    Facilitated diffusion can occur without the aid of proteins in the cell membrane.

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

    Gated ion channels can open or close in response to stimuli like chemical signals.

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

    An equilibrium in the diffusion process means that molecules continue to move but at equal rates in both directions.

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

    Match the following processes with their correct descriptions:

    <p>Diffusion = Movement of molecules from high concentration to low concentration Facilitated Diffusion = Diffusion of substances through transport proteins Equilibrium = Equal concentration of molecules on both sides of a membrane Concentration Gradient = Difference in concentration between two areas</p> Signup and view all the answers

    Match the type of transport with its characteristics:

    <p>Passive Transport = Does not require energy Facilitated Transport = Utilizes transport proteins Active Transport = Requires energy input Simple Diffusion = Direct movement across the membrane</p> Signup and view all the answers

    Match the following terms with their relevant functions:

    <p>Channel Proteins = Facilitate the passage of ions across membranes Carrier Proteins = Change shape to transport larger molecules Aquaporins = Specialized channels for water transport Transport Proteins = Assist in facilitated diffusion of solutes</p> Signup and view all the answers

    Match the following types of solutions with their effects on cells:

    <p>Hypotonic Solution = Causes cells to swell Hypertonic Solution = Causes cells to shrink Isotonic Solution = No net movement of water Equilibrium = Molecules move at equal rates in both directions</p> Signup and view all the answers

    Match the following molecules with their ability to cross cell membranes:

    <p>Small Nonpolar Molecules = Easily pass through the bilayer Ions = Require facilitated diffusion Large Polar Molecules = Need transport proteins to cross Water = Can pass through aquaporins in membranes</p> Signup and view all the answers

    Match the following types of proteins with their functions:

    <p>Channel proteins = Allow rapid passage of water and small ions Carrier proteins = Transport specific molecules across the membrane Gated channel proteins = Open in response to specific stimuli Ion channel proteins = Facilitate the movement of specific ions like Na+ and K+</p> Signup and view all the answers

    Match the following terms with their definitions:

    <p>Hypertonic = Higher solute concentration compared to another solution Hypotonic = Lower solute concentration compared to another solution Isotonic = Equal solute concentration on both sides of a membrane Osmosis = Diffusion of water through a selectively permeable membrane</p> Signup and view all the answers

    Match the following scenarios with their outcomes:

    <p>Freshwater fish in saltwater = Fish loses water and may die Cell in hypotonic solution = Cell swells and may burst Cell in hypertonic solution = Cell shrivels and loses water Cell in isotonic solution = No net movement of water occurs</p> Signup and view all the answers

    Match the following ions with their roles in cellular functions:

    <p>Sodium (Na+) = Involved in nerve signal transmission Potassium (K+) = Regulates cell membrane potential Calcium (Ca2+) = Important for muscle contraction and neurotransmitter release Chloride (Cl-) = Contributes to maintaining osmotic balance</p> Signup and view all the answers

    Match the following features with their corresponding protein types:

    <p>Channel proteins = Pore-like structure for ion movement Gated channel proteins = Specific binding site for regulatory molecules Carrier proteins = Undergo conformational change to transport molecules Aquaporins = Facilitate rapid water transport</p> Signup and view all the answers

    Study Notes

    Diffusion and Facilitated Diffusion

    • Diffusion: Movement of molecules from high concentration to low concentration, driven by the concentration gradient until equilibrium is reached.
    • Concentration Gradient: The difference in concentrations of molecules across areas.
    • Equilibrium: Achieved when molecules are evenly distributed across a membrane, with equal rates of movement in both directions.

    Facilitated Diffusion

    • Involves transport proteins that assist in the movement of substances across the cell membrane.
    • Passive Transport: Facilitated diffusion does not require energy, as substances move down their concentration gradients.
    • Types of transport proteins:
      • Channel Proteins: Create pores for molecules like water and ions to pass through quickly (e.g., aquaporins for water).
      • Gated Channel Proteins: Open in response to specific stimuli (chemical, electrical) to allow molecules to pass.
      • Carrier Proteins: Change shape to transport specific molecules across the membrane (important for glucose transport).

    Ion Channels

    • Allow selective movement of charged ions (sodium, potassium, calcium, chloride) across cell membranes.
    • Gated Channels: Open or close based on stimuli, essential for cellular functions, especially in nerve cells.

    Osmosis

    • Osmosis: The diffusion of water across a selectively permeable membrane from areas of higher water concentration to lower water concentration.
    • Tonicity:
      • Hypertonic Solution: Higher solute concentration; water moves out of cells, causing them to shrink.
      • Hypotonic Solution: Lower solute concentration; cells take in water, potentially leading to swelling or bursting.
      • Isotonic Solution: Equal solute concentration; cells remain stable.

    Osmotic Pressure

    • Builds up as water enters a cell; helps maintain cell shape and support in plants.
    • Plant cells become turgid in hypotonic environments but are prevented from over-expanding by their cell wall.

    Controlling Osmosis

    • Freshwater organisms employ mechanisms to control water intake (e.g., producing dilute urine) to prevent cell lysis.
    • Contractile Vacuoles: Found in some freshwater protists; expel excess water to regulate osmotic pressure.

    Active Transport

    • Active Transport: Requires energy (ATP) to move substances against their concentration gradients (from low to high concentration).
    • Mainly carried out by protein pumps in the membrane.
    • Also enables transport of larger molecules via vesicle processes like endocytosis (into the cell) and exocytosis (out of the cell).

    Homeostasis and Cell Function

    • Homeostasis: The balance and maintenance of a stable internal environment within a cell.
    • Dynamic equilibrium requires continuous adjustments in response to internal and external changes to stay near set points.

    Diffusion and Facilitated Diffusion

    • Diffusion: Movement of molecules from high concentration to low concentration, driven by the concentration gradient until equilibrium is reached.
    • Concentration Gradient: The difference in concentrations of molecules across areas.
    • Equilibrium: Achieved when molecules are evenly distributed across a membrane, with equal rates of movement in both directions.

    Facilitated Diffusion

    • Involves transport proteins that assist in the movement of substances across the cell membrane.
    • Passive Transport: Facilitated diffusion does not require energy, as substances move down their concentration gradients.
    • Types of transport proteins:
      • Channel Proteins: Create pores for molecules like water and ions to pass through quickly (e.g., aquaporins for water).
      • Gated Channel Proteins: Open in response to specific stimuli (chemical, electrical) to allow molecules to pass.
      • Carrier Proteins: Change shape to transport specific molecules across the membrane (important for glucose transport).

    Ion Channels

    • Allow selective movement of charged ions (sodium, potassium, calcium, chloride) across cell membranes.
    • Gated Channels: Open or close based on stimuli, essential for cellular functions, especially in nerve cells.

    Osmosis

    • Osmosis: The diffusion of water across a selectively permeable membrane from areas of higher water concentration to lower water concentration.
    • Tonicity:
      • Hypertonic Solution: Higher solute concentration; water moves out of cells, causing them to shrink.
      • Hypotonic Solution: Lower solute concentration; cells take in water, potentially leading to swelling or bursting.
      • Isotonic Solution: Equal solute concentration; cells remain stable.

    Osmotic Pressure

    • Builds up as water enters a cell; helps maintain cell shape and support in plants.
    • Plant cells become turgid in hypotonic environments but are prevented from over-expanding by their cell wall.

    Controlling Osmosis

    • Freshwater organisms employ mechanisms to control water intake (e.g., producing dilute urine) to prevent cell lysis.
    • Contractile Vacuoles: Found in some freshwater protists; expel excess water to regulate osmotic pressure.

    Active Transport

    • Active Transport: Requires energy (ATP) to move substances against their concentration gradients (from low to high concentration).
    • Mainly carried out by protein pumps in the membrane.
    • Also enables transport of larger molecules via vesicle processes like endocytosis (into the cell) and exocytosis (out of the cell).

    Homeostasis and Cell Function

    • Homeostasis: The balance and maintenance of a stable internal environment within a cell.
    • Dynamic equilibrium requires continuous adjustments in response to internal and external changes to stay near set points.

    Diffusion and Facilitated Diffusion

    • Diffusion: Movement of molecules from high concentration to low concentration, driven by the concentration gradient until equilibrium is reached.
    • Concentration Gradient: The difference in concentrations of molecules across areas.
    • Equilibrium: Achieved when molecules are evenly distributed across a membrane, with equal rates of movement in both directions.

    Facilitated Diffusion

    • Involves transport proteins that assist in the movement of substances across the cell membrane.
    • Passive Transport: Facilitated diffusion does not require energy, as substances move down their concentration gradients.
    • Types of transport proteins:
      • Channel Proteins: Create pores for molecules like water and ions to pass through quickly (e.g., aquaporins for water).
      • Gated Channel Proteins: Open in response to specific stimuli (chemical, electrical) to allow molecules to pass.
      • Carrier Proteins: Change shape to transport specific molecules across the membrane (important for glucose transport).

    Ion Channels

    • Allow selective movement of charged ions (sodium, potassium, calcium, chloride) across cell membranes.
    • Gated Channels: Open or close based on stimuli, essential for cellular functions, especially in nerve cells.

    Osmosis

    • Osmosis: The diffusion of water across a selectively permeable membrane from areas of higher water concentration to lower water concentration.
    • Tonicity:
      • Hypertonic Solution: Higher solute concentration; water moves out of cells, causing them to shrink.
      • Hypotonic Solution: Lower solute concentration; cells take in water, potentially leading to swelling or bursting.
      • Isotonic Solution: Equal solute concentration; cells remain stable.

    Osmotic Pressure

    • Builds up as water enters a cell; helps maintain cell shape and support in plants.
    • Plant cells become turgid in hypotonic environments but are prevented from over-expanding by their cell wall.

    Controlling Osmosis

    • Freshwater organisms employ mechanisms to control water intake (e.g., producing dilute urine) to prevent cell lysis.
    • Contractile Vacuoles: Found in some freshwater protists; expel excess water to regulate osmotic pressure.

    Active Transport

    • Active Transport: Requires energy (ATP) to move substances against their concentration gradients (from low to high concentration).
    • Mainly carried out by protein pumps in the membrane.
    • Also enables transport of larger molecules via vesicle processes like endocytosis (into the cell) and exocytosis (out of the cell).

    Homeostasis and Cell Function

    • Homeostasis: The balance and maintenance of a stable internal environment within a cell.
    • Dynamic equilibrium requires continuous adjustments in response to internal and external changes to stay near set points.

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    Explore the concepts of diffusion and facilitated diffusion in cell biology. This quiz will test your understanding of how molecules move through cell membranes and the role of proteins in this process. Get ready to dive into the fascinating world of cellular transport mechanisms!

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