Introduction to Biology: Cell Membrane Movement
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Questions and Answers

Which of the following best describes diffusion?

  • Movement down a concentration gradient (correct)
  • Movement from lower to higher concentration
  • Movement of water only
  • Movement against a concentration gradient
  • Osmosis is the movement of molecules from a concentrated solution to a dilute solution.

    False

    What is the role of a partially permeable membrane?

    To allow some molecules to pass while blocking others.

    Active transport requires __________ to move molecules against a concentration gradient.

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

    Match the following types of movement with their descriptions:

    <p>Diffusion = Movement of molecules from high to low concentration Osmosis = Diffusion of water through a partially permeable membrane Active Transport = Movement against a concentration gradient using energy</p> Signup and view all the answers

    What happens to animal cells in a concentrated solution?

    <p>They lose water and shrink</p> Signup and view all the answers

    Plant cells can burst in dilute solutions due to the pressure of water uptake.

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

    Name one example of where active transport occurs in the human body.

    <p>Glucose absorption in the small intestine.</p> Signup and view all the answers

    Study Notes

    Introduction to Biology

    • Biology covers various topics, including classification, cells, and movement across cell membranes.

    Cell Membrane Movement

    • Passive Transport: Movement of molecules with the concentration gradient, no energy needed.

      • Diffusion: Net movement of molecules from higher to lower concentration.
      • Facilitated Diffusion: Diffusion aided by transport proteins.
      • Osmosis: Diffusion of water across a selectively permeable membrane.
    • Active Transport: Movement of molecules against the concentration gradient, requiring energy (ATP).

      • Used when cells need substances in small quantities.
    • Examples of active transport processes:

      • Absorption of nutrients in the small intestine.
      • Uptake of ions by root hairs in plants.

    Types of Movement Across the Membrane

    • Active transport requires special pump proteins.

    • Passive Transport has three types: - diffusion - osmosis - facilitated diffusion

    Osmosis

    • Movement of water molecules from a dilute solution to a concentrated solution across a selectively permeable membrane.
    • A solution with a higher solute concentration is called hypertonic; a solution with a lower solute concentration is called hypotonic; a solution with an equal solute concentration is called isotonic.

    Consequences of Osmosis in Animal Cells

    • In dilute solutions, animal cells take up water, swell, and may burst.
    • In concentrated solutions, animal cells lose water and shrink.

    Consequences of Osmosis in Plant Cells

    • In dilute solutions, plant cells take up water, swell, and become turgid (firm). The cell wall prevents bursting.
    • In concentrated solutions, plant cells lose water, the vacuole shrinks, and the cell membrane pulls away from the cell wall (plasmolysis). The cell becomes flaccid.

    Diffusion in Animals

    • Oxygen from the air enters the blood in the lungs.
    • Carbon dioxide leaves the blood and enters the air in the lungs.
    • Absorption of nutrients from the digestive system in the small intestine.

    Diffusion in Plants

    • Carbon dioxide from the air enters the leaves.
    • Oxygen leaves the leaves.

    Solution

    • A solution is a liquid mixture of two or more substances.
    • Solvent: The substance that dissolves other substances.
    • Solute: The substance that dissolves in the solvent forming a solution.
    • Aqueous solution: A solution where water is the solvent.

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    Description

    This quiz focuses on the fundamental concepts of cell membrane movements, including passive and active transport mechanisms. You'll explore processes such as diffusion, osmosis, and the roles of transport proteins. Test your understanding of how substances move across cell membranes in biological systems.

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