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Вопрос 76

Which sex chromosome does a human egg cell carry?

  1. Always an X chromosomeПравильный ответ
  2. Either an X or a Y chromosome, depending on the egg
  3. Always a Y chromosome
  4. Both an X and a Y chromosome together

Объяснение

The cells that produce eggs hold two X chromosomes and nothing else at this pair, so whichever of the two an egg receives, it is an X. The idea that an egg might carry a Y chromosome would require a Y to be present in the mother's cells in the first place, and it is not.

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