A eukaryotic diploid cell from an organism with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown below. A diploid cell from this individual begins to go through meiosis.After the completion of meiosis I, it becomes two cells.One of these two cells now undergoes meiosis II.Which of the following is a possible normal combination of chromosomes in one of the subsequent two cells after the completion of meiosis II?

Question

A eukaryotic diploid cell from an organism with the ZZ-ZW sex determination system has two pairs of autosomes and a pair of sex chromosomes, Z and W, shown below.  A diploid cell from this individual begins to go through meiosis.After the completion of meiosis I, it becomes two cells.One of these two cells now undergoes meiosis II.Which of the following is a possible normal combination of chromosomes in one of the subsequent two cells after the completion of meiosis II?

Quizplus · Accepted Answer

During the completion of meiosis I in a cell with ZZ-ZW sex determination system, the two homologous Z chromosomes pair up and separate, while the non-homologous W chromosomes remain unmatched. Thus, after meiosis I, each cell will have one Z chromosome and one W chromosome. 
In the subsequent meiosis II, the sister chromatids of each chromosome will separate, resulting in 4 haploid cells overall. 
Option D is possible because one of the cells can get one W chromosome and one Z chromosome that has the a and B alleles respectively. However, Options A, B, and C are not possible because they each require the presence of 4 chromosomes, which is not possible in cells of ZW system.

A Eukaryotic Diploid Cell from an Organism with the ZZ-ZW