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Micro & Immunology · single question

Which statement about platelets is the EXCEPTION — i.e., generally NOT true?

  1. Platelets are produced by fragmentation of bone marrow megakaryocytes (NOT derived from clotting factor VIII, which is an unrelated coagulation protein)
  2. Platelets have an average circulating lifespan of about 7 to 10 days
  3. Average platelet counts can show some variation between sexes in certain population studies
  4. Platelets play a central role in primary hemostasis (forming the initial platelet plug)
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Correct answer: A. Platelets are produced by fragmentation of bone marrow megakaryocytes (NOT derived from clotting factor VIII, which is an unrelated coagulation protein)

Platelets are anucleate cell fragments derived from the fragmentation of bone marrow megakaryocytes — they have no biological relationship to clotting factor VIII (a separate coagulation cascade protein deficient in hemophilia A). Platelet lifespan (~7-10 days) and their central role in primary hemostasis are both accurate; some population studies have found modest average differences in platelet counts between men and women, though this finding varies and is a less universally 'definitive' fact compared with the clearly false factor VIII claim.

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