Junctions, Adhesion and the Extracellular Matrix · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.

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Science · Organisms & Life Processes · ages 20-22
Name ______________________   Date ____________

  1. Which junctions let small molecules pass directly between cells?

    • Gap junctions
    • Tight junctions
    • Anchoring junctions

  2. Which junction type seals membranes into leak proof belts?

    • Gap junctions
    • Anchoring junctions
    • Tight junctions

  3. Desmosomes weld cells together through linkers tied to intermediate filaments.

    Circle one:   True   False

  4. Identical stem cells sit on stiff ground and on soft ground. What happens?

    • Both turn to bone alike
    • The stiff ground group leans to bone, the soft group to nerve or fat
    • Both turn to nerve alike

  5. A sheet of cells is stretched again and again, and its anchoring junctions tear out. What best explains it?

    • Too many gap tunnels opened
    • The junctions lost their filament links inside
    • The matrix turned too soft

  6. How do integrins let a cell hold the matrix and sense it?

    • They grip the mesh outside and the filaments inside
    • They dissolve the nearby collagen
    • They seal the membrane shut

  7. Coating a dish with extra collagen guarantees stem cells turn to nerve.

    Circle one:   True   False

  8. A student says sealing junctions and passing junctions do the same work. What is the error?

    • Both jobs need filaments
    • Sealing blocks flow between cells while passing connects interiors
    • Gap tunnels also seal fluid out
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Answer key

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  1. Gap junctions · Gap junctions open gated tunnels for ions and tiny signals.
  2. Tight junctions · Tight junctions stitch membranes shut so fluid cannot sneak between cells.
  3. True · That filament tie is what lets pulling forces spread across the sheet.
  4. The stiff ground group leans to bone, the soft group to nerve or fat · Stiffness read through adhesions switches fate.
  5. The junctions lost their filament links inside · Without the internal tie, an anchor rips straight out under pull.
  6. They grip the mesh outside and the filaments inside · That two sided grip carries force and signals across the membrane.
  7. False · Collagen adds strength, and stiff ground leans cells toward bone, not nerve.
  8. Sealing blocks flow between cells while passing connects interiors · Tight junctions block sneaking fluid, gap junctions wire interiors together.
Worksheet · LightMySky