Practice question

In meiosis II, homologous chromosomes have already segregated in meiosis I, and only sister chromatids must separate at anaphase II. If one pair of chromatids fails to divide, that meiosis II division yields one n+1 chromatid pair and one n-1 chromatid lacking that chromosome. The other meiosis II division, derived from the normal secondary gametocyte, proceeds correctly and forms two haploid normal gametes. Thus only two of four products are abnormal, with 50% normal haploids retained, contrasting with meiosis I nondisjunction where all four gametes are aneuploid.