Antibody Diversity, Memory and What Tolerance Failure Costs · seed 1 · A4, ink-friendly. The answer key prints on its own page for grown-ups.
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Endless antibodies, faster second meetings

Science · The Human Body · ages 21-22
Name ______________________   Date ____________

  1. Which antibody class is secreted first in a primary response?

    • IgG
    • IgE
    • IgM

  2. Where do B cells mature?

    • In the thymus
    • In the bone marrow
    • In the spleen only

  3. Each mature B cell clone carries a unique binding site built by gene shuffling.

    Circle one:   True   False

  4. What happens to a developing B cell that grips self strongly in the marrow?

    • It is kept as a memory cell
    • It is deleted by apoptosis
    • It switches to making histamine

  5. Why is the second response to a virus faster and stronger?

    • Memory B cells from the first meeting respond at once
    • The virus becomes weaker on its own
    • Red blood cells start making antibodies

  6. How does a ragweed allergy unfold on second exposure?

    • IgM bursts the pollen grains directly
    • Helper T cells eat the pollen whole
    • IgE on mast cells binds pollen and triggers histamine release

  7. A mature B cell that binds self but gets no helper T cell signal should keep making antibody anyway.

    Circle one:   True   False

  8. A student says autoimmunity and allergy are the same thing: too much immunity. What is the correction?

    • One targets self, the other targets a harmless outsider
    • Both are caused by weak bone marrow alone
    • Neither involves antibodies at all
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Answer key

For grown-ups. Fold this page away before handing over the rest.

Endless antibodies, faster second meetings W1-mt_5YXKhiOqoA-s1

  1. IgM · Plasma cells release IgM early, and strong IgG follows later or on re-exposure.
  2. In the bone marrow · B cells are generated and mature in the bone marrow, where tolerance starts.
  3. True · Random segment joins give nearly every clone its own receptor.
  4. It is deleted by apoptosis · Clonal deletion removes strongly self-reactive cells before they can do harm.
  5. Memory B cells from the first meeting respond at once · Surviving memory cells skip the slow first steps and pour out better-binding IgG.
  6. IgE on mast cells binds pollen and triggers histamine release · IgE made at first exposure arms mast cells, which spill histamine when pollen returns.
  7. False · Missing helper approval marks it for death, which is peripheral tolerance at work.
  8. One targets self, the other targets a harmless outsider · Each is a specific tolerance failure with a different target, not general excess strength.
Worksheet · LightMySky