A/L Biology

Grade 12 — Term 3

1 study note · 10 practice questions · Aligned with NIE syllabus

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This term in the Idasara Academy app has 1 lesson (NIE Unit 5). For it, this page gives you the points you must know and one exam-style question with its answer. None of it needs an account.

Home/Subjects/Biology/Grade 12 — Term 3

Lessons in This Term

Immunity

NIE Unit 5 · NIE term: Grade 12, term 3 – Grade 13, term 1
1 note · 10 questions

What you must know

  • Primary vs Secondary Immune Response: Primary response has a lag period (5-10 days) with low IgM-dominated titer; secondary exposure triggers rapid, massive, high-affinity IgG production driven by memory cells.
  • Active vs Passive Immunity: Active immunity involves production of one's own antibodies/memory cells (natural: infection; artificial: vaccines); Passive immunity provides immediate, temporary antibodies without memory (natural: maternal IgG/IgA via placenta/colostrum; artificial: anti-venom).
  • Major Histocompatibility Complex (MHC): MHC-I molecules present endogenous antigens to CD8+ Cytotoxic T cells on all nucleated cells; MHC-II molecules present exogenous antigens to CD4+ Helper T cells exclusively on APCs (dendritic cells, macrophages, B cells).

Try one question

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
Show the answer

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.

A model question written by Idasara on the exam pattern. It is not from a past paper.

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Grade 12 — Term 1 Grade 12 — Term 2 Grade 13 — Term 1 Grade 13 — Term 2 Grade 13 — Term 3