Immunity — A/L Biology

How do I practise Immunity?

1 question with a worked solution

1. Which class of immunoglobulins is the only antibody capable of crossing the maternal placenta to confer passive immunity to the developing human fetus?
   1. A) IgE
   2. B) IgM
   3. C) IgA
   4. D) IgG
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   Correct answer: D) IgG

   Immunoglobulin G (IgG) is the most abundant serum antibody monomer and the only immunoglobulin class with Fc regions recognized by placental transport receptors, enabling transplacental passage to the fetus.

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   Step 1: Review antibody classes: - IgA: found in secretions (saliva, tears, colostrum). - IgM: pentamer, first responder in primary immune response. - IgE: allergic reactions and parasitic infections. - IgG: principal circulating antibody; uniquely crosses placenta. Answer: IgG.
   Modelled on: the A/L Biology examination pattern

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Where does Immunity fit in the syllabus?

Year 2 · Term 1