Question

If a cell with 2n=60 chromosomes undergoes meiosis, but one chromosomal non-disjunction event occurs during meiosis II, that is, one chromatid pair fails to separate normally, how many chromosomes will be in the four resulting daughter cells? [This is an application of your knowledge of meiosis; see Fig. 15-3]

A. 30, 30, 29, 29

B. 30, 30, 31, 31

C. 31, 31, 39, 39

D. 30, 30, 31, 29

E. None of these combinations

Answer 1

Answer: D. 30, 30, 31, 29

Explanation:

After meiosis-I, two cells will be formed and each cells consists of 30 chromosomes. In general, after meiosis-II, four cells are formed and each cell must have 30 chromosomes.

One cell of meiosis-I may have normal cell division and the two cells of meiosis-II will have 30 chromosomes each, i.e., 30 & 30

But in second cell of meiosis-I due to non-disjunction, one two chromatids of one chromosome move into one cell and other cell do not have that chromosome. So, one cell contains 31 chromsomes and other cell contains 29 chromosomes ( 31 & 29)