Biology Chapter: Water Movement and Membrane Permeability
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Questions and Answers

What occurs in the sodium-potassium pump when a phosphate group is detached from ATP?

  • It increases the rate of sodium ions influx into the cell.
  • It allows potassium ions to move out of the cell more easily.
  • It stops all transport processes immediately.
  • It undergoes a conformational change to return to its original position. (correct)
  • Which of the following is a key distinguishing feature of plant cells compared to animal cells?

  • Central vacuoles (correct)
  • Presence of lysosomes
  • Number of mitochondria
  • Presence of cell membrane
  • What is the primary consequence of placing plant cells in a hypertonic solution?

  • They will become turgid.
  • They will swell and burst.
  • They will remain unaffected.
  • They will undergo plasmolysis. (correct)
  • Which mechanism is specifically involved in the transport of water across cell membranes?

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

    According to the fluid mosaic model, what primarily contributes to the dynamic structure of the cell membrane?

    <p>Mobile lipids and proteins</p> Signup and view all the answers

    What is the primary function of ATP in the cell?

    <p>Providing energy for cellular processes</p> Signup and view all the answers

    How do high salt concentrations affect plant cells?

    <p>They cause water loss and plasmolysis</p> Signup and view all the answers

    In the fluid mosaic model, what does the term 'fluid' refer to?

    <p>The lateral movement of lipids and proteins in the membrane</p> Signup and view all the answers

    What adaptation helps organisms in cold climates maintain plasma membrane fluidity?

    <p>Increasing unsaturated fatty acids</p> Signup and view all the answers

    What distinguishes rough ER from smooth ER?

    <p>Rough ER synthesizes proteins, while smooth ER synthesizes lipids</p> Signup and view all the answers

    What role do aquaporins play in cells?

    <p>They facilitate water transport across the membrane</p> Signup and view all the answers

    Which type of molecules can easily pass through the plasma membrane without transport proteins?

    <p>Small nonpolar molecules</p> Signup and view all the answers

    In a U-tube with different solute concentrations, what will happen to the water levels?

    <p>Water will move from low to high solute concentration</p> Signup and view all the answers

    Study Notes

    Water Movement in Solutions

    • Water moves from areas of lower solute concentration to areas of higher solute concentration (osmosis).
    • An example is an U-tube with a semipermeable membrane separating a solution of 0.2 M glucose from a solution of 0.6 M KCl.
    • Water will move from the left side (0.2 M) to the right side (0.6 M).

    ATP Synthesis

    • Adenosine Triphosphate (ATP) is synthesized in the mitochondria of cells.

    Impact of High Salt

    • High salt concentrations in the soil create a hypertonic solution.
    • This causes plant cells to lose water, leading to plasmolysis.

    AQP1 Gene

    • The AQP1 gene codes for aquaporins.
    • Aquaporins facilitate water transport across the membrane.
    • A mutation could reduce water uptake, but cells can still take up water through osmosis (although slower without aquaporins).

    Plasma Membrane Permeability

    • The plasma membrane allows selective permeability.
    • Small nonpolar molecules (e.g., oxygen) can pass easily through without transport proteins.

    Fluid Mosaic Model

    • The “fluid” aspect of the fluid mosaic model refers to lipids and proteins moving laterally within the membrane.
    • Lipids and proteins are held together by weak hydrophobic interactions.

    Cell Membrane Adaptations

    • Organisms in cold climates have cell membranes with more unsaturated fatty acids to maintain fluidity and prevent tight packing at low temperatures.

    Surface Area to Volume Ratio

    • Cells with a higher surface area to volume ratio are more efficient in exchanging materials.
    • Surface area and volume ratio are important considerations for material exchange.

    Protein Structure in Membranes

    • Proteins embedded in the membrane have regions that interact differently with the membrane interior and aqueous environment.
    • Region 1 (hydrophilic) interacts with the membrane interior.
    • Region 2 (hydrophobic) interacts with the aqueous environment.

    Smooth vs Rough ER

    • The rough endoplasmic reticulum (ER) synthesizes and packages proteins for export.
    • The smooth ER cannot synthesize and package proteins.

    Sodium-Potassium Pump

    • The detachment of a phosphate group from ATP induces a conformational change in the sodium-potassium pump.
    • This conformational change allows the pump to return to its original position.

    Distinguishing Features of Plant Cells

    • A central vacuole is a distinguishing feature of plant cells compared to animal cells.

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    Description

    Explore the principles of water movement in solutions, ATP synthesis, and the effects of salt on plant cells. This quiz covers osmosis, aquaporins, and the selective permeability of plasma membranes. Test your understanding of these vital biological concepts.

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