Order of meiotic divisions In meiosis, daughter cells arise through two successive divisions. Which statement correctly describes the order of these divisions?

Difficulty: Easy

Correct Answer: First division is reductional; second is equational

Explanation:


Introduction / Context:
Meiosis ensures halving of chromosome number for sexual reproduction. Knowing which division reduces ploidy and which separates sister chromatids is central to interpreting genetic outcomes and nondisjunction errors.



Given Data / Assumptions:

  • Meiosis consists of meiosis I and meiosis II.
  • Homologous chromosomes pair and recombine before segregation.
  • Sister chromatids remain together through meiosis I (except at chiasmata).


Concept / Approach:
Meiosis I is reductional: homologs segregate to different daughter cells, reducing 2n to n. Meiosis II is equational: sister chromatids separate, akin to mitosis, preserving haploid number.



Step-by-Step Solution:

Identify the stage that halves chromosome number: meiosis I (reductional).Identify the stage that separates sister chromatids: meiosis II (equational).Choose the option that states “first reductional, second equational.”


Verification / Alternative check:
Most textbooks refer to meiosis I as the reduction division and meiosis II as the equational division.



Why Other Options Are Wrong:

  • Equational first then reductional is incorrect.
  • Two reductional or two equational divisions do not describe standard meiosis.
  • Nondisjunction exceptions exist but do not redefine the canonical scheme.


Common Pitfalls:
Confusing chromatid and homolog separation due to both involving “pairs.”



Final Answer:
First division is reductional; second is equational

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